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Damburger
2009-May-12, 05:57 PM
Right now, our space construction techniques are quite primitive. We stick modules together, and unfold the odd solar panel or similar. Basically, its IKEA in orbit. Perfectly suitable for Mir/ISS, 20t satellites, and basic interplanetary spacecraft like the Apollo program - but somewhat limited.

Has there been any work, or is there anything in the pipeline anywhere, on more advanced space construction techniques, which would allow us to build larger, more open, space stations, and also things like mirrors for telescopes, solar sails, tethers etc.?

PraedSt
2009-May-12, 06:22 PM
Specifically techniques, as opposed to the item itself? I'm not sure.

Carbon nanotube research? Although that would come under materials...

Damburger
2009-May-12, 06:30 PM
Specifically techniques, as opposed to the item itself? I'm not sure.

Carbon nanotube research? Although that would come under materials...

More of how to build the kind of variety of structures in space as we are able to on Earth (although obviously, Earth structures would be useless in space). Rather than sending up stuff ready assembled (which constrains you to the physical limits of the launcher) being able to send up raw materials or components up and being able to construct general structures without having to do assembly on the ground first.

Lets say a structure you wanted in space required a strong, rigid beam that is longer than the largest dimension of any available launcher's payload bay. Does anyone have a clue how to go about doing something like that?

rommel543
2009-May-12, 06:34 PM
There are a lot of other issue around building structures in space.

Cost wise it's more efficient to create pre-built modular structures that can be stuck together like tinker toys. Also if there is a structural issue in a module it can be sealed off from the rest of the structure, where as large open areas don't have that ability. If anything I can see more 'corridor-ed' structures that have bulkheads that can be closed to seal off different areas, with other modular like structures off the corridor.

Creating big open structures poses issues regarding filling it with breathable air. The bigger the area the more that needs to be sent up.

The other issue is that these structures have millions of little pieces in them. Screws connectors, wires, etc. These little components are huge problems when you have to wear thick gloves in space (as the crew servicing the HST know to well).

rommel543
2009-May-12, 06:46 PM
More of how to build the kind of variety of structures in space as we are able to on Earth (although obviously, Earth structures would be useless in space). Rather than sending up stuff ready assembled (which constrains you to the physical limits of the launcher) being able to send up raw materials or components up and being able to construct general structures without having to do assembly on the ground first.

Lets say a structure you wanted in space required a strong, rigid beam that is longer than the largest dimension of any available launcher's payload bay. Does anyone have a clue how to go about doing something like that?

Something like a large strong rigid beam would not be able to be created in space with our current technology. Gravity plays too much of a role in our manufacturing to duplicate the same process in orbit. Rather you would need to create a massive structure that you would be able to induce a huge amount of pressure to keep the molten metal in the form long enough for it to harden. Then of course, how are you going to build the massive structure to create the massive beam in. A more likely idea would be creating smaller beams that can be connected together, similar to the construction here on earth. When they are building sky scrapers there isn't a single massive steel beam that runs through the building. Rather it's smaller beams that bolt together. In fact I was watching a show on Discovery Channel where they are creating a modular apartment building. Each of the apartments are created separate from the main building structure. They are then lifted and put into place.

raptorthang
2009-May-12, 06:47 PM
Space construction techniques are far from primitive. A better word is 'limited'. Rommel gives a good response. I'll just second the last statement of his first posting. Be sure to watch the upcoming service to the Hubble Space Telescope and the immense co-ordination it takes to refit some part. There is no room for error. Last night I changed the brakes on my Jeep and had to run down to the auto parts store for a bolt. No hardware store in space.

rommel543
2009-May-12, 06:51 PM
Last night I changed the brakes on my Jeep and had to run down to the auto parts store for a bolt. No hardware store in space.

And if you dropped that bolt, it didn't float away or worse float into sensitive parts of your Jeep (or your tool bag :D )

PraedSt
2009-May-12, 06:51 PM
Rather than sending up stuff ready assembled (which constrains you to the physical limits of the launcher) being able to send up raw materials or components up and being able to construct general structures without having to do assembly on the ground first.

Lets say a structure you wanted in space required a strong, rigid beam that is longer than the largest dimension of any available launcher's payload bay. Does anyone have a clue how to go about doing something like that?
Ok I see what you mean. I think you've hit upon the stumbling block though- the physical limits of our launchers. For example, to build your beam, we'd need a factory of some sort that was already in orbit. So you're back to modular construction.

I've read about autonomous robotic construction in the future.

And there's always Bigelow Aerospace (http://en.wikipedia.org/wiki/Bigelow_Aerospace) (which really is a novel technique).

ravens_cry
2009-May-12, 06:54 PM
The USSR did some experiments with welding in space. One technique that is very versatile, but less practical on Earth, is electron beam welding, as it needs to be conducted in a vacuum, something orbit has in abundance.

NEOWatcher
2009-May-12, 06:55 PM
Space construction techniques are far from primitive. A better word is 'limited'. Rommel gives a good response.
I'll agree to that.

I have a hard time understanding why we would need a large open space anyway. It would be great for tourism, but until space tourism is a common event, I don't think the application will be there.

That leaves something like large trusses. I have seen plans (or conceptual ideas) for some kind of machine that can roll tubes and form trusses some many years ago. (similar in how seamless gutters are made). I'm not sure if that can be more efficient than truss segments though. You still need to send up the material, and now the machine to form it.
Again; No application until we get into high volume construction.

novaderrik
2009-May-12, 07:26 PM
houses on the ground are made from pre-fabricated components- roof and floor trusses, pre made windows, doors, cabinets, etc..
why would building something in space be any different?
think of the structures we could build in space if we kept lobbing Spacelab sized modules on bigger rockets instead of the relatively small modules that fit in the cargo bay of the shuttle...

Damburger
2009-May-12, 07:49 PM
I'd like to apologise for the word 'primitive'. I only meant that space construction is in its infancy; I am well aware of the high level of technology and skill required for the current level of construction technology.

Even if a large open space is not useful for a habitat (personally I think it is) building bigger observatories than can fit in a payload bay will require more sophisticated construction techniques. After the ISS is completed this sort of thing is the next logical step.

Inflatable modules, welding in space, gloves that allow better dexterity (mechanical pressure ones perhaps?), are the kinds of technologies I'm talking about. Not just for creating big structures though; for creating generic structures. Having everything you want to build in space designed from scratch, and having its own unique (and difficult) assembly procedure is part of the huge cost of a space station. You don't have to reinvent scaffolding and concrete every time you want to build an office block.

Ara Pacis
2009-May-13, 12:59 PM
I don't think it will be to difficult to arrive at solutions to the basic problems. It might be good to start with a large inflatable/expadable structure in which to work; to stabilize the thermal cycles, provide ambient lighting and prevent parts from escaping if the are inadvertently released.

If you need a large part, make it from smaller parts with welds, rivets, or bolts. If that won't work, consider altering a launcher so that it can carry longer items into space by boosting the entire rocket structure to orbit and essentially strapping long items into the outside of the rocket with a large aerodynamic fairing.

Protect workers by giving them suits designed for construction that may look more like a lobster than an ape-suit. Such a suit might be a sleepin-bag-sized pod and have a stabilzed attachment at the base for stability an a selection of hand powered and electromechanical waldoes as well as ye basic industrial space gauntlet.

Almost anything can be made of basic pre-made parts launched in bulk and assembled like an erector set with adjustable jigs to speed up attachment processes. Then you would build subunits that can be attached to other subunits to make a whole structure.

Are there any particular issues with space construction for which someone wants to find specific answers?

Antice
2009-May-13, 01:27 PM
you dont need a fully enclosed spacedock. just a sunshade and perhaps a low weight truss enclosure with chicken wire netting to catch anything that might come loose or be dropped.
as for the spacesuit. a semi robotic mini craft would make sense. with it's own rcs thrusters for safety built in. one do not realy need legs after all so the sleeping bag shape might be quite useful. also. if you have a truss enclosure you can have robotic gantry cranes for most of the vacuum work. they can move around on rails built into the trusses of the enclosure.

Trakar
2009-May-13, 07:10 PM
Has there been any work, or is there anything in the pipeline anywhere, on more advanced space construction techniques, which would allow us to build larger, more open, space stations, and also things like mirrors for telescopes, solar sails, tethers etc.?

Not sure it this fits your request but it is a personal interest and is (IMO) the only practical way to do large scale construction in NEO.

(Note this article is almost 30 years old)
http://web.media.mit.edu/~minsky/papers/Telepresence.html

And a few more articles of a bit more recent vintage for reference and/or those interested in a few more aspects of the topic.


NASA Telerobotics Program
2.2.4 Free Flying Servicers
http://ranier.hq.nasa.gov/Telerobotics_page/FY96Plan/Chap2g.html (http://ranier.hq.nasa.gov/Telerobotics_page/FY96Plan/Chap2g.html)

MIT Space Systems Lab
(telepresence section is near end and small, but the enitre article os of interest to space construction/large-scale projects so I included it)
http://www.nss.org/settlement/L5news/1983-MIT.htm (http://www.nss.org/settlement/L5news/1983-MIT.htm)

ROBOTICS FOR ASSEMBLY, INSPECTION, AND MAINTENANCE OF SPACE
MACROFACILITIES - http://www.ri.cmu.edu/pub_files/pub2/whittaker_william_red_l_2000_1/whittaker_william_red_l_2000_1.pdf (http://www.ri.cmu.edu/pub_files/pub2/whittaker_william_red_l_2000_1/whittaker_william_red_l_2000_1.pdf)

Real World Teleoperation via Virtual Environment Modelling - http://vered.rose.utoronto.ca/publication/1997/Milgram_Ballantyne_ICAT1997.pdf (http://vered.rose.utoronto.ca/publication/1997/Milgram_Ballantyne_ICAT1997.pdf)

Robonaut: A Robotic Astronaut Assistant - http://robotics.estec.esa.int/i-SAIRAS/isairas2001/papers/Paper_AM113.pdf (http://robotics.estec.esa.int/i-SAIRAS/isairas2001/papers/Paper_AM113.pdf)

(more available upon request - note .pdf files require free adobe reader)

Damburger
2009-May-13, 08:30 PM
Thanks, I'll give that lot a read.

I figured telepresence might be important, space walks are hard expensive and require extra supplies to support astronauts.

cjameshuff
2009-May-13, 09:04 PM
you dont need a fully enclosed spacedock. just a sunshade and perhaps a low weight truss enclosure with chicken wire netting to catch anything that might come loose or be dropped.

A full enclosure would diffuse light and reflect radiated heat, protecting workers from temperature extremes without the need for bulky layers of insulation, and protecting powered down/opened up equipment from those temperature extremes as well...the work item will be better lit, and you won't have to worry about grabbing something that's come to equilibrium temperature in shadow, or things freezing up or breaking. "Chicken wire" or netting could pose a safety hazard through being difficult to see, and it could be a tangle hazard as well.

A full enclosure could also be inflated without any need for a deployable truss structure. It needn't be pressurized to anything like a full atmosphere of pressure, just enough to hold its shape. A more ambitious higher-pressure version could reduce or eliminate the pressure differential across the workers' suits, reducing the restrictiveness of working in a pressurized suit, but a low pressure version would be lightweight, robust to punctures, and easy to repair.

Trakar
2009-May-13, 09:21 PM
A full enclosure would diffuse light and reflect radiated heat, protecting workers from temperature extremes without the need for bulky layers of insulation, and protecting powered down/opened up equipment from those temperature extremes as well...the work item will be better lit, and you won't have to worry about grabbing something that's come to equilibrium temperature in shadow, or things freezing up or breaking. "Chicken wire" or netting could pose a safety hazard through being difficult to see, and it could be a tangle hazard as well.

A full enclosure could also be inflated without any need for a deployable truss structure. It needn't be pressurized to anything like a full atmosphere of pressure, just enough to hold its shape. A more ambitious higher-pressure version could reduce or eliminate the pressure differential across the workers' suits, reducing the restrictiveness of working in a pressurized suit, but a low pressure version would be lightweight, robust to punctures, and easy to repair.


Might be better to let it be opaque and use thin sheet flexible solarcells on the outside an "airdock" instead of a drydock. I agree that minimal pressure would be best.

Still prefer telepresence where most of the work force could be kept on the ground (home workers). Each human should be able to handle several automated work units at the same time, mostly doing oversight and minimal guidance tasks. You'd want a few onsite workers handling quick reaction tasks and a few spacewalk troubleshooters to handle the inevitable issues unaddressable by automated and telepresence capabilities. But if you're building and repairing lots of mega projects (power sats, habitats, etc.,.) it could develop into quite the profession and involve a lot of "ordinary" people in orbital industries.

raptorthang
2009-May-14, 03:29 PM
There could be an industry but it depends a lot on the future cost of satelite and other launches etc. As long as the cost to send a kg into space is in the thousands then an industry might flourish that manipulates that kg in the future...especially from the ground either as a repair, re-use of the part, structure, etc. If, however, launch costs are reduced then it might become like repairing your toaster... easier to buy a new one at $12 than pay someone $30/hour to fix it.

There isn't going to be much more in orbit in the next couple of decades than there is now. In fact, depending on the fate of the ISS, there could be less.

rommel543
2009-May-14, 05:10 PM
Well running with both the sun shield and tele-presence, you could send 'works' up and house them in the sun shield. When they go to work, they are put into a VR type of environment where the worker can "see" though the eyes of a worker bot. The human worker, moving their arms and hands cause the work bots arms and hands to move. You could then have shifts of workers, each shift using the same bot. It would kind of like working in a video game (except with no restarting if you screw up and no save file :P).

novaderrik
2009-May-14, 07:28 PM
Well running with both the sun shield and tele-presence, you could send 'works' up and house them in the sun shield. When they go to work, they are put into a VR type of environment where the worker can "see" though the eyes of a worker bot. The human worker, moving their arms and hands cause the work bots arms and hands to move. You could then have shifts of workers, each shift using the same bot. It would kind of like working in a video game (except with no restarting if you screw up and no save file :P).
why bother sending them up in the first place, if all they are going to do is put on a VR helmet and gloves? just do it from the ground instead.
right now, here on earth, we've got 20 year old people sitting in air conditioned rooms remotely controlling unmanned aircraft equipped with cameras and missiles that are doing patrols over Iraq and Afghanistan- and probably a few other place, too. if they can do that on a routine basis, then remote controlled robots in space should be easy.
of course, if all that's up there is a robots, then why bother with the big structure in the first place?

Ara Pacis
2009-May-14, 07:56 PM
A full enclosure could also be inflated without any need for a deployable truss structure. It needn't be pressurized to anything like a full atmosphere of pressure, just enough to hold its shape. A more ambitious higher-pressure version could reduce or eliminate the pressure differential across the workers' suits, reducing the restrictiveness of working in a pressurized suit, but a low pressure version would be lightweight, robust to punctures, and easy to repair.

I was thinking that the assembly volume would be large since it's for something that can't be launched in one piece. I wouldn't inflate the entire structure since it would take a lot of air and risk deflation if it's punctured. I was thinking that it might be attached to the main construction scaffolding at as few as two points. Then, the enclosure would have a few inflatable ribs in its walls to give it the proper shape. Thus, it would be less like a balloon and more like a an inflatable raft. A combination of the sun, translucency and interior reflectivity of the enclosure and electric lights on the scaffolding would provide proper 720 degree illumination. I'd include multiple combination airline/com-line/power jacks along the scaffolding to increase work shift duration because sometimes the best tool for the job is a human, even if a lot of the work is done by robots and tele-manipulation. Once interior portions of a human-rated construction are complete, then people can finish work on the interior in a shirtsleeve environment.

cjameshuff
2009-May-14, 10:00 PM
I was thinking that the assembly volume would be large since it's for something that can't be launched in one piece. I wouldn't inflate the entire structure since it would take a lot of air and risk deflation if it's punctured. I was thinking that it might be attached to the main construction scaffolding at as few as two points. Then, the enclosure would have a few inflatable ribs in its walls to give it the proper shape. Thus, it would be less like a balloon and more like a an inflatable raft. A combination of the sun, translucency and interior reflectivity of the enclosure and electric lights on the scaffolding would provide proper 720 degree illumination. I'd include multiple combination airline/com-line/power jacks along the scaffolding to increase work shift duration because sometimes the best tool for the job is a human, even if a lot of the work is done by robots and tele-manipulation. Once interior portions of a human-rated construction are complete, then people can finish work on the interior in a shirtsleeve environment.

With a low pressure and large volume, little fill gas would be required, deflation through any reasonably sized holes would be slow, and the air/nitrogen/helium currents near the breach would be easy to deal with while laying a patch on the breach. Even with a low pressure fill gas, with forced ventilation, the currents would pick up debris like lost screws, dust from welding/cutting, etc. and carry it into traps and filters. A reactive gas would also passivate surfaces and help avoid problems like vacuum welding.

Pressurized ribs would need to be at higher pressures, making for more difficult repairs and more rapid loss of structural support if punctured. However, they would allow a fully evacuated interior, allowing things like electron beam welding to be used...

This sort of shelter would actually be of even greater benefit for telepresence. It's hard to build cameras that can adapt as well as human eyes, the more even lighting will be of particular benefit.

A note about the hard shell suits: they seem like they'd only offer any substantial benefits over telepresence if the arms can access the outside for performing fine manipulation tasks. It'll continue improving, but telepresence currently can't come close to matching human vision and dexterity.

Ara Pacis
2009-May-15, 01:43 AM
Well, maybe a combination of inflatable ribs and low-pressure inflated interior would work, or it could be adjusted over time as needed for different tasks. I was thinking that inflatable ribs might be better because there would be less thermal issues than with a metal pole and it might provide a more rounded enclosure shape, which might make light reflection more even. The enclosure might resemble a cylinder, sphere or a football this way, instead of a platonic solid like with tent-poles.

Would a reactive gas be necessary? Assuming most of the parts are machined, punched, bent, ground and welded on Earth, those passivation layers might be obtained in that environment before shipping to orbit. There might be a temptation to think that we want to pack the material as densly as possible for shipping to orbit and do any bending and forming on-sight, but metal is dense and the likelihood is that decking, tubing, beams and other expanded structural metal will reach the launcher's mass limit before it reaches the volume limit. Depending on the space structure being built, a lot may still be shipped up as basic prefab hexagononal, cubic, octagonal or triangular cross-sections modules and attached in orbit. When I speak of prefab modules, I don't mean self-contained units like with the ISS, but simpler airtight "boxes" that get bolted or welded together into a larger structure with a smaller surface area. Then all that can get wrapped in space shielding.

As for the cameras, I think telepresense robotics might want to make use of sterovision and laser guidance if they aren't already. Premarking of parts with scan codes for identification and digital recall of the layout of attachment work would help too.

Trakar
2009-May-15, 03:04 AM
In referring to telepresence systems, while you may want a few units where there is a more authentic telepresence capability (ie., stereovision, fine detail manipulation with interactive feedback grip pressure and inertia sensors, etc.,.), for the most part, I see the vast majority of such systems as being relatively simple in function and capability, and largely automated, with the human operator serving in more of a supervisory role controlling work teams of remote units rather than in a full time virtual presence full control of all activities.
Scan codes would work, we might even take a page out of the ant play book and just use squirts various chemical combinations to relay basic information and lay trails. For automated function, probably be best to have minimal capability in each unit, and then have a large command or central processing unit that tracked individual units, overall progress, and could be called upon by the individual units for detailed task programming. The idea is to keep the actual work units as simple and generalized in function and capability as possible and then use the central control unit and human operators as the specialized controllers which would utilize these general units to perform complex and intricate functions.

Antice
2009-May-15, 04:53 AM
shipyard rule no 1. Keep the assembly as simple as possible.
modern shipyards build the ships with pre assembled modules that are then fused together. these modules comes pre fitted with everything except the furniture. and i do mean everything. On orbit assembly would do well to copy this mode of thinking. with each part of the puzzle comming as complete as possible up to the yard. so that only slotting it into place and fusing the parts together has to be done.
For a first gen spaceyard the parts will have to all come from earth. and their size and mass is mostly restricted by the launchers. Later on when we may have some space industry going someone might have gotten a space foundry up and running. and you can add on factory modules that makes the modules for the spaceyard. that would allow bigger modules to be made inside the factory modules then moved over to the spaceyard by tugs for final assembly.
As for handling these modules. you do not want a ton of simple multi purpose robots. you want a gantry crane able to move the parts into their place and then a smaller one to do the actual fusing of the parts. the last line of robotics are the eyeball mark 2 to inspect the jobs done prior to certification and deliver of the finished structure/ship.

Modern day Naval shipyards are very good at doing this kind of things, so instead of reinventing the wheel it's good to copy the methods used and adapting them to space.

Trakar
2009-May-15, 06:02 AM
Modern day Naval shipyards are very good at doing this kind of things, so instead of reinventing the wheel it's good to copy the methods used and adapting them to space.

It all makes good sense, when you have the luxury of using shipyard facilities, unfortunately, most shipyard modules don't have to be lugged onto several thousand tons of volitile chemicals and then shoved at several gees of acceleration into the extremes of orbital environment to be fit together. this works well enough for relatively small structures like the ISS. For larger structures, we might still do well to follow the module construction concept (though such really isn't necessary due to the nature of the environment), but constructing the individual modules will probably be best accomplished in orbit. With the telepresence/automated construction capability, the bulk of the launches are just raw materials which are largely insensitive to launch conditions or the orbital environment. even launcher reliability isn't that big an issue with this type of system, much of the payload raw material may even be recoverable from a failed launch, not so a multibillion dollar pre-constructed module which is going to require a big, low-gee launcher with very high redundancy and reliability (read as very expensive).

Antice
2009-May-15, 06:42 AM
modern ship modules weigh in at several hundred tonnes a piece. they are often moved long distances before reaching their assembly point. Sometimes clear ot the other side of the world. launching 10 or 20 or even 30 tonne+ parts is not an issue as long as they are propperly packed and bracers added for launch. They have to fit inside the launcher shroud ofc. witch is a rather big limiter on how big modules might get when launched from earth.

Once assembled the surplus bracing materials can be recycled into new parts for craft in an on orbit production chain to make suport struts etc for engine mounts or even fuel tanks

Trantor
2009-May-15, 03:00 PM
I've always liked the idea of capturing a small metal rich asteriod and putting it in a high Earth orbit. Then we can use it as a base for interplanetary operations and as a source of raw materials for manufactoring. Tunneling to make living and working environments would yield a lot of raw materials that would be used in manufactoring. Small asteriods could even be hollowed out to make large spacecraft. I know this is not something that will happen anytime soon, but I think it's the only way that large scale manufactoring will ever happen in space.

samkent
2009-May-15, 03:54 PM
Are you people watching the shuttle astronauts repairing Hubble as we speak? With the difficulty they are having even the simplest task is taking foooreeeever.
There is no way you can consider assembling a bunch of frames and then fleshing them out. The minimum would be complete prefabs that latch themselves together.
The asteroid idea would just make things worse.

raptorthang
2009-May-15, 04:39 PM
I've always liked the idea of capturing a small metal rich asteriod and putting it in a high Earth orbit. Then we can use it as a base for interplanetary operations and as a source of raw materials for manufactoring. Tunneling to make living and working environments would yield a lot of raw materials that would be used in manufactoring. Small asteriods could even be hollowed out to make large spacecraft. I know this is not something that will happen anytime soon, but I think it's the only way that large scale manufactoring will ever happen in space.

'Mining the asteroids' might make sense one day but not in the next couple centuries. Having worked at a mine site, I understand the incredible infrastructure it takes to extract metals from ore. Mines have daily deliveries of dozens of parts and supplies from industrial supply companies from all over the globe.

Also what is this 'all-purpose' asteroid...copper and lead and nickle and zinc and bauxite and ...... then the amount of energy needed to refine the ores...the infrastructure to refine....the infrastructure to engineer a purpose of these metals...construction of.... Yikes.

It takes a dedicated mission and several space walks just to manipulate a few bolts and slots on Hubble. Unlike on Star Trek, there is no magical microwave oven-looking box one can put a piece of bauxite into and out pops an aluminum rivet.

Trakar
2009-May-15, 04:52 PM
Are you people watching the shuttle astronauts repairing Hubble as we speak? With the difficulty they are having even the simplest task is taking foooreeeever.
There is no way you can consider assembling a bunch of frames and then fleshing them out. The minimum would be complete prefabs that latch themselves together.
The asteroid idea would just make things worse.

Actually this is more an example of manufacturing on the ground and then repairing or putting together in orbit, and the types of problems associated with trying to use humans in spacesuits to accomplish those tasks.
Automated/telepresence systems perfroming in situ construction utilizing designs created with that process in mind, are a completely different situation.

Of course, watching astronauts perform such maintenance/repair work today is rather the equivilant of our early Greek and Roman ancestors trying to recover cargo from a ship wreck in a couple hundred feet of water. They probably could have done it, but not with the ease or efficiency that is possible today for even extreme depth salvage and recovery. Comparing the current Hubble repair/maintenance mission, with the types of future construction missions being discussed, is really apples and oranges.

PraedSt
2009-May-15, 05:01 PM
Are you people watching the shuttle astronauts repairing Hubble as we speak? With the difficulty they are having even the simplest task is taking foooreeeever.
I've thought about this. Building quickly in space is limited due to the lack of gravity (obviously). There is no firm base from which to apply leverage. To paraphrase someone famous (can't remember who!), with no place to stand, moving a mountain takes forever.
This limitation would also apply to robots.
So I think the first thing to do would be to build a simple, rotating structure of reasonable size. This would take time, but once complete, everything else could be constructed much faster.

Antice
2009-May-15, 05:07 PM
The asteroid idea is currently not feasible with current tech levels.
at first you would do the fully completed modules aproach. but later as designs and methods are developed you can start launching modules that are less self contained. one improvement at a time one could develop these technologies. spacebased manufacture needs several tech's that are currently only on paper. each of these enabling technologies should be developed one by one as need arises.

the spaceyard at it's most basic and hence most economical form is a simple truss with solar panels. a couple of shuttle style arms and the electronics and station keeping equipement it needs to stay up there for a long time.
this gantry could be light enough to fit on a single launch, and stil be versatile enough to be used instead of the shuttle for on orbit assembly operations. A orion/soyuz/dragon/whatever is made craft could be launched to move any needed astronauts up to this platform when assembly jobs needs be done. the parts to be assembled could be launched separately, and could be grabbed by the robot arms and tied down until all parts are present. the astronauts comes next to last with fuel tanks comming up last. the astronauts assemble everything and go back home. next up the crew of the moon/mars wherever craft arrives with the next capsule and dock with the craft for departure.
later with the demand for larger interplanetary craft adding a hab module and mabe another truss/robotcrane/power coupler might be desired.

In a lot of cases less is more. the assembly yard can grow as needed until you end up with something that is very versatile and well tested.

Trakar
2009-May-15, 05:38 PM
'Mining the asteroids' might make sense one day but not in the next couple centuries. Having worked at a mine site, I understand the incredible infrastructure it takes to extract metals from ore. Mines have daily deliveries of dozens of parts and supplies from industrial supply companies from all over the globe.

Also what is this 'all-purpose' asteroid...copper and lead and nickle and zinc and bauxite and ...... then the amount of energy needed to refine the ores...the infrastructure to refine....the infrastructure to engineer a purpose of these metals...construction of.... Yikes.

It takes a dedicated mission and several space walks just to manipulate a few bolts and slots on Hubble. Unlike on Star Trek, there is no magical microwave oven-looking box one can put a piece of bauxite into and out pops an aluminum rivet.

Again, however, this seems (to me) to be confusing mining, refining and production and construction as it is typically done here on Earth with how it might be done on such an asteroidal body.

A great deal of minerals will probably never be economically recoverable from diffuse undifferentiated asteroidal sources. Nor does it make sense to ship these elements in raw ore form from the bodies where they are extracted. But refined billets, rods and spools of wire or sheeting would make good sense and such can be easily processed into finished structural elements. As for the mining and processing, that depends upon the nature of the asteroidal ore and the types of elements one is seeking to recover. There are lots of such methods, though I seriously doubt if any of them would be deployed in Earth orbit. For the most part, anywhere within the Earth-Moon system, it is almost always going to be cheaper and easier to launch semi-refined and/or lightly manufactured materials from the surface of the Earth than it is going to be to recover, refine and process to the same point from extra-terrestrial sources. This is primarily do to the required infra structure for these additional steps, and the pre-existing mineral recovery and industrial base upon the Earth.

Trakar
2009-May-15, 05:49 PM
I've thought about this. Building quickly in space is limited due to the lack of gravity (obviously). There is no firm base from which to apply leverage. To paraphrase someone famous (can't remember who!), with no place to stand, moving a mountain takes forever.
This limitation would also apply to robots.
So I think the first thing to do would be to build a simple, rotating structure of reasonable size. This would take time, but once complete, everything else could be constructed much faster.

Actually, free-fall can be beneficial to construction of large, lightweight structures that will never be expected to maintain their shape and form under gee loading.

(technically we are dealing with freefall in orbit, not a lack of gravity. If the astronauts were standing on a platform tower that stretched from the ground to shuttle orbit height they would still weigh around 90% of what they do on the surface of the Earth. It is the fact that they are in orbit and freefalling that they feel weightless, not because the force of the Earth's gravity has fallen off that much at a mere 200 miles above the Earth's surface.)

The reason we experience problems right now, is a combination of experience, design and tools, more than inherent problems with construction under freefall conditions.

PraedSt
2009-May-15, 06:24 PM
Actually, free-fall can be beneficial to construction of large, lightweight structures that will never be expected to maintain their shape and form under gee loading.
The reason we experience problems right now, is a combination of experience, design and tools, more than inherent problems with construction under freefall conditions.
Yes, I know the difference between gravity and freefall.

Coming back to the point, I'm going to have to disagree with you here. :)
While a lack of gravity is definitely better for the final product, construction of the product is a complete pain.
First, you have to actively anchor yourself to a large mass before every application of force. This takes time. And because it's an active process, you can forget to do it.
Second, and this has already been mentioned here- things have a habit of drifting away.

Artificial gravity will automatically and passively anchor you (or your robot), to a mass. You can build smaller items within the rotating enclosure at Earth speed, and once they're done, release them into freefall.
Yes, this approach will have problems. For example, the structure has to be quite large and very simple, otherwise there's no point bothering. But I think it'll result in faster construction.

All hypothetical anyway. We'll never know until we have a race up there. :lol:

Trakar
2009-May-15, 06:57 PM
Yes, I know the difference between gravity and freefall.

Coming back to the point, I'm going to have to disagree with you here. :)
While a lack of gravity is definitely better for the final product, construction of the product is a complete pain.
First, you have to actively anchor yourself to a large mass before every application of force. This takes time. And because it's an active process, you can forget to do it.
Second, and this has already been mentioned here- things have a habit of drifting away.

Artificial gravity will automatically and passively anchor you (or your robot), to a mass. You can build smaller items within the rotating enclosure at Earth speed, and once they're done, release them into freefall.
Yes, this approach will have problems. For example, the structure has to be quite large and very simple, otherwise there's no point bothering. But I think it'll result in faster construction.

All hypothetical anyway. We'll never know until we have a race up there. :lol:


Again, I think the biggest problem is that some of us are thinking about using conventional earth-bound tools and techniques to build conventional design and form structures under conditions where the only variable is a lack of effective weight. Whereas I am talking about an entirely different set of variables, such as single-piece lightweight structures kilometers in length that would crumple to a twisted lump under even partial gee loading, or the more rigid and gee tolerant single piece 100 meter bulkhead module for a habitat (hint, you can't build the big spinning dock construction unit, until you can build the big dock unit under conditions of no weight and then spin it up!), etc.,. The anchoring isn't that big of an issue and can be accomplished with a free hand or a clamping unit attached to the unit applying torque. If you are talking about anchoring for other purposes, you'll have to explain, I don't see a problem.

PraedSt
2009-May-15, 07:28 PM
single-piece lightweight structures kilometers in length that would crumple to a twisted lump under even partial gee loadingWhat exactly are you thinking of building? :)

I believe I've addressed your other points.

End the end of the day, I'm pretty sure we'll end up with a variety of techniques, each best suited to the task at hand. Much like we have down here.

Damburger
2009-May-15, 07:58 PM
Unlike on Star Trek, there is no magical microwave oven-looking box one can put a piece of bauxite into and out pops an aluminum rivet.

Well, sort of.

If you can get from Bauxite to powdered aluminium, there are I believe rapid manufacturing techniques that can do just that. Not being an engineer, I don't know the full details, just that it is possible (and also, handily, it requires a vacuum. One thing a space construction site isn't short of).

Antice
2009-May-15, 08:50 PM
I have some issues with building big in leo.
1. you need periodic reboosts in order to maintain orbit. friction can be such a drag ya know. and leo isnt totaly above the atmosphere in that regard.
2. you initially have to launch everything from earth. while cheaper than building a whole new set of factories all over the solar system to garner up the stuff for building it's stil pretty darn costly.
3. we just dont have any experience refining the metals we need in a low g/ zero G environment.
4. the smelters and other bits and pieces needed to make those factories to make the parts to make a spaceship. those have to be launched initially from earth as well.
5. cost. pure and simple. building a big spacestation to make stuff you could make with a smaler one is a waste of resources.


Ramble mode on
ISRU experience from the moon will be invaluable when trying to design the first space based smelters and factories. and it would necessarily be quite large. it has to replicate a lot of steps we take for granted on earth.

extraction -> purification -> refining -> alloying -> shaping -> combining shapes into parts -> assembling into complex units -> assembling into a finished ship.

Add to this that you need hundreds if not thousands of unique parts in order to make a spaceship. even when discounting the computers to help control em. on orbit factories are not near term applications. i suspect it's more like like mid to long term.
If peeps wants all that to ever happen they have to focus on what can we do now. and how can we do it profitable or at least worth the costs in science/engineering advances.

What kind of on orbit assembly projects can we sell to the public in order to get funding? :think:
going to the moon can be done with just a bigger launcher with X billion dollars cost. it can be done with on orbit assembly and smaller launchers we already have for maybe the same cost or more. depending on how you calculate your costs. one still has to design the space gantry and moon vehicle after all.
A Mars mission will have to have on orbit assembly unless you want to spend on an even bigger launcher than the ares V even... some peeps would love that. but it would not really advance space exploration much. how about reuse of the interplanetary vehicles?
could something be done about Telecom satellites? a ion engine tug could maybe grab hold of old decommissioned ones and bring em to the gantry for storage and recycling. better than to let em keep littering up there at least.

/end ramble mode

Trakar
2009-May-15, 11:33 PM
What exactly are you thinking of building? :)

In that particular instance I was thinking of SPS arrays, but there are a number of potential large structures that would serve their functional purpose quite well in a weightless environment but would have to be overbuilt to handle synthetic gee-loading if built in a spinning structure. Additionally, if you are going to work in a space limited rotating structure you might as well build it on Earth and launch it. My only real objection to groundside building, is that it limits the size of the units and the necessary overbuiding required by that process.

Of course differing projects and requirements will require different techniques and practices. My purpose wasn't to say: "my way is the only right way and everyone else is wrong," it was merely to point out the benefits and possibilities of that these concepts offer, and to offer counter point to those who seemed to be saying in situ construction is completely unworkable and undesirable.

PraedSt
2009-May-15, 11:55 PM
...
Heh. Hang around here long enough and you'll realise I have two obsessions. SSTO, and rotating habitats. Huge rotating habitats.

Trakar
2009-May-16, 12:34 AM
I have some issues with building big in leo.
1. you need periodic reboosts in order to maintain orbit. friction can be such a drag ya know. and leo isnt totaly above the atmosphere in that regard.
2. you initially have to launch everything from earth. while cheaper than building a whole new set of factories all over the solar system to garner up the stuff for building it's stil pretty darn costly.
3. we just dont have any experience refining the metals we need in a low g/ zero G environment.
4. the smelters and other bits and pieces needed to make those factories to make the parts to make a spaceship. those have to be launched initially from earth as well.
5. cost. pure and simple. building a big spacestation to make stuff you could make with a smaler one is a waste of resources.
(...)


Point 1. True, especially over extended periods. Its not like there's a breeze or anything, but large, low mass structures would be particularly vunerable to drag over extended periods. but that which is a significant consideration at 200nm, is much less so at 400nm. 500 miles would probably be a decent LEO construction altitude, low enough to still be fairly easy to launch to, but far enough below the inner Van Allen belt to avoid having to hard shield all the electronics. Even a large low-pressure balloon should persist for extended timeframes without dangerous orbital decay at that altitude, so you should have plenty of time for construction. Boosting super lightweight structures brings its own set of problems. Distributed microgee thrust units, careful attention to both force application and orbital stresses (a long axis object can find itself subject to significant stresses when one section of it is in a significantly lowerer energy orbit than another section of it -tidal forces).

Point 2. Agreed, that's one reason you might want to get the launch costs down as low as possible.

Point 3. Again agreed. Its definitely an important skill we will have to learn, but I see little need to force it at the start of our expansion, when we have access to the industrial facilities of our entire society a mere few hundred miles away.

point 4. Yes and no. Yes, the final production equipment would have to be launched, but if we are talking about a manufacturing system that accepts rolls of aluminium sheeting and thin steel wire and lightweight trusses, structural panels, etc.,. We aren't talking about anything extremely complicated or overwhelming.

point 5. not sure why you would need a large station to perform orbital construction.

Trakar
2009-May-16, 12:36 AM
Heh. Hang around here long enough and you'll realise I have two obsessions. SSTO, and rotating habitats. Huge rotating habitats.

Priorities of my own, as well.

Ara Pacis
2009-May-16, 05:17 AM
Yes, we need to build big in order to bring costs down. Why is that important? Well, besides all the talk of building in space for the sake of saving on delta-v costs and launch limitations, there are some more important earthly reasons: environmentalism. Yes, the sooner we can start mining and refining basic industrial materials on the moon (and yes, I suppose, on asteroids too eventually) the sooner we can stop mining and refining them here.

There are two basic savings that I can see here:
1 - Less destructive and unsightly mining which can cause problems with local air and water and take up what could be ecological greenspace.
2 - Less need for high energy demands from various unclean energy supplies, such as coal-fired electricity generation, nuclear power or gigantic hydropower projects. Solar PV and thermal systems on the moon might be able to supply enough electricity for such heavy industry and if we need to use nuclear, few people will complain about a nuke plant on the moon.

In exchange, basic refined material might be imported to earth from the moon. There may be arguments as to whether it would be economical, but that will depend on the markets and the regulations of the day.

Antice
2009-May-16, 08:26 AM
Point 1. True, especially over extended periods. Its not like there's a breeze or anything, but large, low mass structures would be particularly vunerable to drag over extended periods. but that which is a significant consideration at 200nm, is much less so at 400nm. 500 miles would probably be a decent LEO construction altitude, low enough to still be fairly easy to launch to, but far enough below the inner Van Allen belt to avoid having to hard shield all the electronics. Even a large low-pressure balloon should persist for extended timeframes without dangerous orbital decay at that altitude, so you should have plenty of time for construction. Boosting super lightweight structures brings its own set of problems. Distributed microgee thrust units, careful attention to both force application and orbital stresses (a long axis object can find itself subject to significant stresses when one section of it is in a significantly lowerer energy orbit than another section of it -tidal forces).

I say we make it a strong back structure. with a solid spine. inflatables can be fine for hab space for the astronauts. but there shouldnt be flimsy stuff used at a construction site like this. too easy to damage it beyond repair. there are advantages to over engineering this kind of structure.


Point 2. Agreed, that's one reason you might want to get the launch costs down as low as possible.

Costs are related to number of launches. the gantry could be done in 1 launch. or 2 if you want it to be a bit bigger. the tele-operators aren't launched into space at all. they will sit on the ground. the parts for the Vehicle that is to be built could be launched on multiple launches. and even on multiple launchers. they rendevouz with the gantry and will be attached to it until the construction is complete.



Point 3. Again agreed. Its definitely an important skill we will have to learn, but I see little need to force it at the start of our expansion, when we have access to the industrial facilities of our entire society a mere few hundred miles away.

Yes. we dont have to force it. looking at launch costs and how they go down when you launch more stuff you end up paying more to get the parts from the moon than from earth. the First LEO gantry isnt there to be used as a permanent shipyard. rather. it's there to test all the technologies needed to mabe build one in one of the Lagrange spots. the gantry can also be expanded with a fuel depot and other desired functions in order to test out viability and performance.



point 4. Yes and no. Yes, the final production equipment would have to be launched, but if we are talking about a manufacturing system that accepts rolls of aluminium sheeting and thin steel wire and lightweight trusses, structural panels, etc.,. We aren't talking about anything extremely complicated or overwhelming.

It has to start some place. and this sounds like a good starting point. :) however. at first everything will have to come from earth as pre built modules.
Even the mining equipment and refineries to make the raw parts that will be turned into modules. :doh:


point 5. not sure why you would need a large station to perform orbital construction.
You dont need a large platform. :hand:
You need a gantry made out of a truss that can grab onto the parts and connect them together. at the minimum. maybe 20 tonnes in all or so for the first gantry and you can add more of them as needed.Imagine 2 cranes sitting on a rail line in a harbour. but instead of on ground the rails are on a truss in space. the length of the truss can vary, and you can have several in parallel as well to increase functionality. :)

Trakar
2009-May-16, 09:55 PM
I say we make it a strong back structure. with a solid spine. inflatables can be fine for hab space for the astronauts. but there shouldnt be flimsy stuff used at a construction site like this. too easy to damage it beyond repair. there are advantages to over engineering this kind of structure.


The problem is launching spine. The system I'm thinking of consists of a couple skylab size units. One that houses structural fabrication units and one that serves as the construction shack, housing the small onsite manned crew, garages for the TelePresenceUnits (repair/maintenance), and the primary groundlink systems which allow surface operators to remotely link into the TPUs and the fabrication units. No need for a big heavy central unit, either for construction base or most large space constructions. SPS systems don't need overbuilt systems which are a waste of money and resources.



Costs are related to number of launches. the gantry could be done in 1 launch. or 2 if you want it to be a bit bigger. the tele-operators aren't launched into space at all. they will sit on the ground. the parts for the Vehicle that is to be built could be launched on multiple launches. and even on multiple launchers. they rendevouz with the gantry and will be attached to it until the construction is complete.


Remember its not just the number of launches its also the type of launches. I'm more in favor of cheap mass launch systems than building a lot of shuttles, I'd prefer a Ram-accelerator booster popping 5 ton units into orbit several times a day to one 20 ton BDB payload every few days.

http://www.fourmilab.ch/documents/rocketaday.html

http://www.fas.org/ota/reports/8904.pdf

http://www.aa.washington.edu/AERP/ramac/Papers-pdf/ISDC-07_spacelaunch-CK.pdf



It has to start some place. and this sounds like a good starting point. :) however. at first everything will have to come from earth as pre built modules.
Even the mining equipment and refineries to make the raw parts that will be turned into modules. :doh:


My concept leaves the mining equipment on the Earth (for now) as well as the initial refining and rough processing. The only thing I'm shipping to orbit are rolls of metal sheeting, wire and perhaps some billets or rods of material for vapor deposit application.



You dont need a large platform. :hand:
You need a gantry made out of a truss that can grab onto the parts and connect them together. at the minimum. maybe 20 tonnes in all or so for the first gantry and you can add more of them as needed.Imagine 2 cranes sitting on a rail line in a harbour. but instead of on ground the rails are on a truss in space. the length of the truss can vary, and you can have several in parallel as well to increase functionality. :)


what do you need a crane for? winches at most, but almost any load can be walked into place by constrution bots/TPUs

Antice
2009-May-17, 05:56 AM
The problem is launching spine. The system I'm thinking of consists of a couple skylab size units. One that houses structural fabrication units and one that serves as the construction shack, housing the small onsite manned crew, garages for the TelePresenceUnits (repair/maintenance), and the primary groundlink systems which allow surface operators to remotely link into the TPUs and the fabrication units. No need for a big heavy central unit, either for construction base or most large space constructions. SPS systems don't need overbuilt systems which are a waste of money and resources.
making the system rugged increases reliability. also. altho modules are weightless they stil have mass. no weight to suport means you can slim the structure down a lot. but Moving 2 15 tonne modules together creates bending moments in the structure that moves them. so it has to be stiff. launching a stiff structure is not a big issue.



Remember its not just the number of launches its also the type of launches. I'm more in favor of cheap mass launch systems than building a lot of shuttles, I'd prefer a Ram-accelerator booster popping 5 ton units into orbit several times a day to one 20 ton BDB payload every few days.

http://www.fourmilab.ch/documents/rocketaday.html

http://www.fas.org/ota/reports/8904.pdf

http://www.aa.washington.edu/AERP/ramac/Papers-pdf/ISDC-07_spacelaunch-CK.pdf



My concept leaves the mining equipment on the Earth (for now) as well as the initial refining and rough processing. The only thing I'm shipping to orbit are rolls of metal sheeting, wire and perhaps some billets or rods of material for vapor deposit application.

Parts construction is a mid term tech. it wont be done until much later. mabe after we have a permanent base on the moon or mars. I suspect we will see the gantry expanded with a fuel depot before any manufacturing is added.




what do you need a crane for? winches at most, but almost any load can be walked into place by constrution bots/TPUs

I call this naming confusion. the cranes would be no more heavy than the shuttle arm. initially it woud only be the spine. and it can go up on one launch. it's not realy heavy. it acts as a the part that no longer get's launched with the crew when the shuttle retires.
It needs 2 arms since it has to be able to grab 2 modules and dock them together. it also needs power and attitude control.

Antice
2009-May-17, 06:34 AM
I think i have to clarify my stance on orbital manufacture a bit.
Thing is. fully automated manufacturing is just not done. and it cant be done currently. here is why:
1. making something from something takes a lot of different operations. each operation requires a specific tool and movements. when you start breaking down what is indeed needed to turn a spool of wire into an electrical cable you find that you need to build a specialized machine for many of the steps. and quite frankly. once the cable is done. it has to be put into the module. now go ask an electrician how many different tools and working modes he has. add freefall to the mix and you might start to begin understanding how complex such a facility would have to be. it wont fit into a single 20 tonne module. And that is just for wires. we havent even started on connectors/pipes/handles/thrustchambers etc etc etc needed to build a spacecraft.
we are talking thousands of unique parts. each with everything from mabe 10 to 30 steps to make. and some up to several thousands of discrete steps in order to make.
Factories arent big just because they make lots of identical items. they are big because they have so many processes. once a step is automated it can spew out lots and lots of identical parts after all.

2. Automation isnt perfect. sometimes the crude shapes from one machine is imperfect enough to escape detection. causing a failure in a later process. mabe even a jam. it takes a human with specilized tools to unjam it. and get it up and working again. NO robot today can even come close to doing this task. it takes knowledge and experience to do stuff like that. so unless one has a true AI you need peeps to oversee those factories. same is true for maintenance.
3. Cost. it's just plain cheaper to launch finished goods with similar masses to the raw materials.

Trakar
2009-May-17, 07:33 AM
I think i have to clarify my stance on orbital manufacture a bit.
Thing is. fully automated manufacturing is just not done. and it cant be done currently. here is why:


Actually most manufacturing done today is highly automated. And the systems I propose are overseen by remote operators and tended by TPUs and onsight controllers.



3. Cost. it's just plain cheaper to launch finished goods with similar masses to the raw materials.


It is cost that motivates me to manufacture inorbit. pre-manufactured goods are bulky and more sensitive to mass launch gee-loading. 5-ton rolls of material are compact and resistant to launch extremes.

Antice
2009-May-17, 03:42 PM
highly automated does not equate fully automated... there are steps in the making of stuff that at current technological levels can only be cost effectively done by a human. machines are great for doing repetitive tasks. freeing up the human resources for more complex matters. what they are not good at is doing diverse tasks. one task = one machine. if you want a machine to go from making one item to another similar item you have to shut it down and exchange tools and programming. There Currently exists NO factory that does without human operators and technicians to keep it running.
for a low volume market like spaceships you cant really save much by copying a car factory either. quite simply because you don't need thousands of like parts. you need only a handful. you are better off trying to use parts that are already used for other products on earth. Buying them cheap. now since you already have all these parts at hand you might as well assemble them into modules before launch. again a cost issue. it's a lot easier to do it in a hangar where human operators have easy access.
G loads at launch for modules that are going to be used to make a spaceship is not an issue. they already have to deal with the loads of being part of a vehicle under thrust. not to mention in some cases even aero braking to save on reaction mass coming back home... foamy packaging will prevent damage to the more sensitive parts. we move pretty delicate stuff all over the world on land and sea already. without breaking it most of the time. dense heavy stuff is sometimes a bigger issue when it comes to G loads due to being easily deformed due to it's own weight. when it hits something it hits hard. and the density makes foam padding less efficient.

One has to remember that it's funding that pays for exploration. NOT dreams. while orbital factories is a neat dream it's not viable with current funding and neither is it needed to explore.
Pri one is to get as much bang for your buck as possible after all.
For the return to moon flights NASA is going for 2 launches and straight there. no on orbit assembly needed. only a simple rendevouz.
For Mars they need to assemble 3 or 4 modules prior to crew arrival. for that a simple gantry crane would suffice. Add some fuel tanks so that the mission becomes less launch sequence critical and you have all that is needed for Mars.
The dreamy stuff is costly and should wait until ISRU systems are able to deliver resources to factories. making the modules on the moon in that case might be more viable than orbital factories even then.
Weightlessness does not confer any magical advantages to structural components. quite the contrary. It makes it harder, while at the same time it's a health hazards for the human operators that we currently cant do without.

Trakar
2009-May-17, 05:06 PM
highly automated does not equate fully automated... there are steps in the making of stuff that at current technological levels can only be cost effectively done by a human. machines are great for doing repetitive tasks. freeing up the human resources for more complex matters. what they are not good at is doing diverse tasks. one task = one machine. if you want a machine to go from making one item to another similar item you have to shut it down and exchange tools and programming. There Currently exists NO factory that does without human operators and technicians to keep it running.

The only things the orbital factories of my design will produce are a few types of folded sheetmetal trusses and some structural panels which will consist of various lengths of some of these trusses tacked together and sandwiched in sheetmetal. I'm not talking about pouring sand and metal in at one end and expecting computers and thruster engines at the other end. Even electrical wiring (which I saw mentioned earlier) would be brought up from the ground based industries. The wiring I mention was intended to be springsteel structural reinforcement elements, bent and tacked to the bent sheet aluminium trusses. The only thing I'm talking about manufacturing in orbit are these basic structural components. And even this process, as discussed would be overseen and augmented by human operators both on the ground and onsite. The primary role of the TPUs and onsite human personnel, is the integration of these structural units into the finished structure, and the installation and outfitting of that structure with the highly manufactured components brought up from the ground.

Trakar
2009-May-17, 05:10 PM
One has to remember that it's funding that pays for exploration. NOT dreams. while orbital factories is a neat dream it's not viable with current funding and neither is it needed to explore.


If all you want to talk about is what is viable given current funding expectations, we can probably knock out almost all manned mission period for the next decade or so (realistically speaking) and most science exploration as well. In fact I don't see a very bright future for NASA, at least not the NASA many of us have known for the last ~50 years.

But the thread was started to talk about possibilities, not what we are realistically going to try and place in orbit in the coming fiscal year.

Antice
2009-May-17, 08:26 PM
thing is. even with 4x the budget you wont make any worthwhile benefit if your raw materials are brought up from the earth. while structural beams and platings can be made easily enough. the outfitting of the hull cant be done with robots yet. there is just too many fiddly tasks that robots suck at involved.
it's just plain more sensible to do it on earth and launch it in easy to handle pieces that fit together. that is how we build big ships ON earth. each part is made in especially made facilities and then moved to the assembly yard for final assembly.
so a sensible time line is to have it all as modules from earth at first. then once space resources are available. moon built ones. sans the parts only made on earth.
Cost effectiveness is important. if it's not cost effective then it's not viable as I see it. I'd rather they spend it on more mars/moon missions instead in that case.

Trakar
2009-May-18, 07:45 AM
thing is. even with 4x the budget you wont make any worthwhile benefit if your raw materials are brought up from the earth. while structural beams and platings can be made easily enough. the outfitting of the hull cant be done with robots yet. there is just too many fiddly tasks that robots suck at involved.


Such as? BTW we aren't talking about "robots," just remotely operated tools, and these tools (TPUs) would far exceed even non-spacesuited human capabilites, range and scope of operations.



it's just plain more sensible to do it on earth and launch it in easy to handle pieces that fit together. that is how we build big ships ON earth. each part is made in especially made facilities and then moved to the assembly yard for final assembly.
so a sensible time line is to have it all as modules from earth at first. then once space resources are available. moon built ones. sans the parts only made on earth.


How many oil rigs, ocean liners or aircraft carriers are built entirely out of pieces no bigger than a refrigerator?



Cost effectiveness is important. if it's not cost effective then it's not viable as I see it. I'd rather they spend it on more mars/moon missions instead in that case.


Piece by surface completed piece, even our ability to build small mostly useless items like the ISS is limited to decades and nearly a trillion dollars. The cost estimates for comparison were given in the links I provided earlier for various launch systems and the various construction systems. If you want something big, like SPS or even really grand like a Standford torus (or even a micro varient similar to the wheel station in 2001), or if you just want to do Mars the right way, you're gonna need in orbit construction and telepresence/automated systems are much better and ultimately cheaper than man variations of orbital construction....unless you prefer going with an Orion (the original - well sorta (http://www.youtube.com/watch?v=avsbVBy-shc)) launch system, which could probably lift some of these in a single throw, maybe even several of them. (sea dragon is another option it might get these up in an acceptably few number (2-3) of boosts -http://www.astronautix.com/lvs/searagon.htm ) (http://www.astronautix.com/lvs/searagon.htm)

Antice
2009-May-18, 08:25 AM
Small pieces is not viable. fully fitted modules is. even remotely operated robotic tools suffer from a distinct lack of flexibility. it's not only the task itself but the ability to reach into the right location. fitting out a module in vacuum is simply doing it the hard way when you can do it in your shirtsleeves on earth prior to launch.
Those superior tools you talk of dont exist yet. and for a good reason too. there is no demand for them.
Minimizing the amount of new hardware on each step of the process increases reliability.
Near term construction such as Mars missions in 2020 - 2030 dont need orbital factories. and there is just no market for it. why build something you dont need to acomplish the same goals?
No matter how large your launcher. at some point you have to start doing it piecemal annyhow. the ISS has suplied a wealth of knowledge on how to acomplish space based assembly operations. so i strongly disagree on the uselessness of it.
No matter how you do it it's stil costly. rocket a day wont work as advertized because assembly costs too. it costs astronaut time in space. and Keeping people alive in space is truly expensive.
A balance must be found.

mugaliens
2009-May-18, 08:33 AM
The asteroid idea is currently not feasible with current tech levels.

I disagree.

First, pick smaller asteroids with orbits that come near Earth but with relatively low relative velocities. Second, use solar-powered ion thrusters to divert smaller asteroids to remote areas. Third, mine using conventional means.

Whether or not it's economically feasible, on the other hand, is a different story.

Antice
2009-May-18, 09:14 AM
I disagree.

First, pick smaller asteroids with orbits that come near Earth but with relatively low relative velocities. Second, use solar-powered ion thrusters to divert smaller asteroids to remote areas. Third, mine using conventional means.

Whether or not it's economically feasible, on the other hand, is a different story.

keywords are 0g mining and refining processes. those needs be developed. some pretty big challenges there.
Not insurmountable but expensive. at some point in time it will likely have to be tackled tho. probably before tackling orbital assembly plants is my guess.

publiusr
2009-May-18, 08:39 PM
The mega module approach with 100 ton pods allows large items to assemble simply, quickly.

If we really want off this rock, we have to look at having infrastructure in space with the same scale as the Mulberries in Normandy. And for its own sake.

Saturn 5--D
http://forum.nasaspaceflight.com/index.php?topic=16913.0
Smaller
http://www.nasaspaceflight.com/2009/05/direct-rebuttal-nasa-analysis-jupiter-launch-vehicle/



Sadly not everyone feels the same
http://forum.nasaspaceflight.com/index.php?topic=17103.msg407788;topicseen#new

Some are happy with small items
Thor, Delta II and Jim
http://forum.nasaspaceflight.com/index.php?topic=17046.0

Trakar
2009-May-18, 09:42 PM
Small pieces is not viable.


Agreed



fully fitted modules is.


Too big/bulky and sensitive to launch gee-forces to work with anything but extremely large and expensive launchers = too expensive.



even remotely operated robotic tools suffer from a distinct lack of flexibility.


Cite or Reference?

Much more so, to all I'm aware of, than human limbs and systems.



it's not only the task itself but the ability to reach into the right location.


Again these systems are much better at doing so than unassisted humans



fitting out a module in vacuum is simply doing it the hard way when you can do it in your shirtsleeves on earth prior to launch.


Which requires a big booster, with limited launch gees which is much more expensive than outfitting in situ orbitally constructed units.



Those superior tools you talk of dont exist yet. and for a good reason too. there is no demand for them.


Neither do the boosters required to lift the prefitted modules you are talking about. My tools are cheaper than your fleet of boosters and the boosters to lift my raw materials already exist.

If we are going to limit ourselves to totally existant technology, there's little since in discussing any of this.



Minimizing the amount of new hardware on each step of the process increases reliability.


Agreed, my system minimizes costs and new development requirements with spinoff applications on the ground and the potential to create an entirely new ground based as well as orbital industries allowing a whole new work-from-home labor force who isn't burning fossil fuels commuting to work everyday, and is involved in building solar power satellites in orbit, recieving rectennas in the desert, etc, etc.,.

Your system requires the development of extremely complex and expensive, inherently unreliable, heavy (but gentle) lift booster systems. Pumping a little extra money into a few selected Aerospace industries with little or no spinoff potential and subject (due to the immense costs of R&D of this nature and the time intervals related to big rocket projects) to the political winds of the day.



Near term construction such as Mars missions in 2020 - 2030 dont need orbital factories. and there is just no market for it. why build something you dont need to acomplish the same goals?


Mars missions!?! ROFLOL by 2020-2030!! (oh my eyes are watering!)

We'll be lucky to do anything beyond leo before mid century.

TPUs are applicable to surface and subsurface use as well as orbital use. SPS systems would be very useful in the very near term.

rommel543
2009-May-19, 07:44 PM
...
What kind of on orbit assembly projects can we sell to the public in order to get funding? :think:
...

I think that this is the root of the matter at hand, although not how we can sell it to the public to get funding, rather how do you sell it to a public corporation. I'm still of the opinion that the only 'sell able' option at the moment is resource collection, aka mining. Whether thats mining asteroids/comets or gases from other planets, until we get colonies on other planets and transport is a viable business, mining is the only sell able idea.

Orbital assembly project could be used to create the crafts to do the actual mining, transportation, and smelting. Depending on the size of the asteroid an entire operation could be set up on or along side the body. Mining and smelting could occur on-site with transports hauling materials and supplies to the sites then hauling finished material back. Smaller asteroids could be collected and hauled to a central mining area for smelting and resource collection. The asteroid belt beyond Mars, for example, could be turned into a massive operation with Ceres being the main outpost (of course that would be far into the future).

Back to the orbital project, as stated the ships and equipment can be created in orbit. Also once a full mining operation is underway, transport to the planet surface will be required, so a warehouse and "space dock" would have to be constructed as well. People and resources can be hauled up, people and resources can be then hauled back down.

Antice
2009-May-19, 09:22 PM
I'm not going to quote the previous reply in order to make this a bit shorter.
Lifting pre kitted modules is done today. on already existing launchers. there is NO additional development effort needed to keep doing that. the number one concern is that without the shuttle there is no longer any on orbit assembly abilities except at the ISS.
Launching a robotic gantry crane makes sense as a replacement for that ability.
a soyuz or orion or any other capsule for that matter can then rendevouz with it, in order to accomplish an assembly task.
Modules can be pre launched and remotely attached together trough tele-operation from earth.
If desired, a living module can be attached to the truss to act as a base camp for the astronauts.
this allows more space walks to be done on a single mission.
As for timeframes for mars. there are more nations than the US looking at that goal. all it lacks is the will to fund it. current technology is up to the task. however it's expensive and nobody is probably going to pay up to make it happen. but hey. I'm an optimist. seeing the first parts of a Mars base camp launched in 2030. it's not impossible.

when it comes to robotic flexibility. you should realy know by now that robots cant do anything that wasnt planned for. they have to stop and wait for updated programming at best. building a space craft is a lot more complex than assembling your average car. (it takes a whole army of the things to build a car actually, and i haven't seen any evidence for car factories doing without humans either)
In order to do all the fitting on orbit with robots you would need thousands of different tools and manipulators. you have to develop those tools as well as the robots. the robots will need robots keeping them suplied etc. The list of robots will just grow and grow. 100% automation is incredibly complex. and you encounter diminishing returns for each layer of automation you add.
terrestrial manufacture robots are quite frankly big heavy brutes too boot. so launching that kind of hardware wont be cheap even with cheap launchers.
By the time you have your factory built and ready to start testing it. everyone else has gone to mars on a similar budget.

I've had the pleasure of breaking in some robots in my career, and i can tell you first hand how a tiny mistake in the positioning of a single sensor can throw everything off balance. not to mention some small un-noticed bug in the code. ofc. once a robot is up and running it can do it's task mindlessly at an incredible rate. that is what makes em useful in factories after all. most robots however don't even resemble that popular image people seem to entertain. they are more often than not just a big piece of machinery that has enough moving parts to give a watchmaker nightmares. not to mention the joy of keeping it all in working order. giving those machines weekly services is not uncommon. if they break they mean big amounts of money lost.The last one i had the joy of working with was as big as a warehouse. :shifty: admittedly.. it was the warehouse.... :lol:

If i am to hazard a guess at the kind of construction robots we will see used first in space, robotic dozer's and diggers rank very high. followed by trucks and paver's. I've seen the national rail road service employ a big monster track layer robotic train for laying down new rails. tunnel borers are also an area that is come pretty far. but for some operations. robots wont be seen for a long time still. some operations aren't cost effectively done on earth with robots. so no freebies on development. that means your space enterprise has to pay the full cost of developing them from scratch.
And lets not forget. gravity is your friend. in many cases a simple task becomes incredibly hard to do when there isn't any gravity around.

Ara Pacis
2009-May-20, 06:14 AM
I think that this is the root of the matter at hand, although not how we can sell it to the public to get funding, rather how do you sell it to a public corporation. I'm still of the opinion that the only 'sell able' option at the moment is resource collection, aka mining. Whether thats mining asteroids/comets or gases from other planets, until we get colonies on other planets and transport is a viable business, mining is the only sell able idea.I disagree. While mining might be a good business for multiple reasons, I think the more immediate sellable commercial endeavor is entertainment, followed by manufacturing of specialized materials and energy collection.


Orbital assembly project could be used to create the crafts to do the actual mining, transportation, and smelting. Depending on the size of the asteroid an entire operation could be set up on or along side the body. Mining and smelting could occur on-site with transports hauling materials and supplies to the sites then hauling finished material back. Smaller asteroids could be collected and hauled to a central mining area for smelting and resource collection. The asteroid belt beyond Mars, for example, could be turned into a massive operation with Ceres being the main outpost (of course that would be far into the future).From a delta-v, time and solar energy standpoint, Venus is probably a better "central mining area" for the Belt than Ceres, although that little planet might have resources of its own to exploit.

samkent
2009-May-20, 04:35 PM
What recourses are we remotely short of that would make off planet mining practical?

Wouldnít it make more sense to mine under the ocean first? You know that other 70% of the planet we havenít dug into.

Trakar
2009-May-20, 05:48 PM
Lifting pre kitted modules is done today. on already existing launchers. there is NO additional development effort needed to keep doing that. the number one concern is that without the shuttle there is no longer any on orbit assembly abilities except at the ISS.


The shuttle is effectively gone/grounded. There is no current replacement scheduled with it's lift capacity or greater. The ISS is a small compact assembly, had to be because everything had to be made to fit within current HLV constraints. How are you going to build an SPS with current boosters sans the STS? How many boosts do you calculate it would take and how much is it going to cost just for the boosting of the sections into orbit?



Launching a robotic gantry crane makes sense as a replacement for that ability.
a soyuz or orion or any other capsule for that matter can then rendevouz with it, in order to accomplish an assembly task.
Modules can be pre launched and remotely attached together trough tele-operation from earth.
If desired, a living module can be attached to the truss to act as a base camp for the astronauts.
this allows more space walks to be done on a single mission.
As for timeframes for mars. there are more nations than the US looking at that goal. all it lacks is the will to fund it. current technology is up to the task. however it's expensive and nobody is probably going to pay up to make it happen. but hey. I'm an optimist. seeing the first parts of a Mars base camp launched in 2030. it's not impossible.


Technology didn't keep us from going to Mars in the '70s (which is what the original plans and beliefs of most of the early Apollo program team indicated was reasonable and doable).



when it comes to robotic flexibility. you should realy know by now that robots cant do anything that wasnt planned for. they have to stop and wait for updated programming at best.]


You are the only one who keeps talking about completely robotic systems, all of the systems I am discussing have robotic elements but are controlled/supervised in their tasks by telepresence operators/supervisors. Programming isn't an issue, and physically they are far superior to humans in both the orbital environment and here on the Earth's surface, with respect to construction work.



building a space craft is a lot more complex than assembling your average car. (it takes a whole army of the things to build a car actually, and i haven't seen any evidence for car factories doing without humans either).


The reason has more to do with costs, than issues of ability or functionality. Human labor (even unionized labor) is still cheap and relatively easy to come by. The cost/investment - expense/profit ratios with respect to such systems is changing, however, primarily due to the ever increasing prevalence and commonality of automated systems, and the ever increasing costs of human labor.



In order to do all the fitting on orbit with robots you would need thousands of different tools and manipulators. you have to develop those tools as well as the robots.

You'd need no more tools than you would with humans doing the fitting, whether it is in orbit or on the surface of the planet.



100% automation is incredibly complex. and you encounter diminishing returns for each layer of automation you add.


Again, you are the only one talking about "100% automation."



terrestrial manufacture robots are quite frankly big heavy brutes too boot. so launching that kind of hardware wont be cheap even with cheap launchers.
By the time you have your factory built and ready to start testing it. everyone else has gone to mars on a similar budget.


the only construction robots that are big heavy brutes, are those that are built where weight isn't an issue or manipulating heavy masses against the pull of gravity is a task requirement, neither of which apply to the systems I have outlined. I don't require a "factory", and all the TPUs needed for even a large construction project should be boostable in 1-2 launch vehicles (20-30 tons of payload). Mars is not really on my radar for projects that need to be done, but if it is to be done properly, you are talking about building a small orbital colony in LEO and then moving it into orbit around Mars, and that will require orbital construction of one form or another.
]

rommel543
2009-May-20, 07:14 PM
What recourses are we remotely short of that would make off planet mining practical?

Wouldnít it make more sense to mine under the ocean first? You know that other 70% of the planet we havenít dug into.

It's not a matter of running short on resources, it a matter of we are screwing up our planet while we are mining those resources. If we rip apart an asteroid, it's not going to kill our marine life, damage an ecology region or require cutting down a rain forest. Not only that, why do we have to suck our planet dry of resources when there are billions of tons of the stuff floating around near by.



I disagree. While mining might be a good business for multiple reasons, I think the more immediate sellable commercial endeavor is entertainment, followed by manufacturing of specialized materials and energy collection.

Yes, short term some companies can make some money on the entertainment aspects, but as more companies get into the business the value is going to drop. Which is good for people like us who can't afford the millions to go up for a ride. Long term however the money is going to be in the resource collection and aspects around it. I can foresee ship building companies making the equipment, mining companies buying the ships to use in the mining, transport companies for hauling the resources and people, etc, etc, etc. Commerce is what drives our society and it's going to be commerce that gets us out into space faster than waiting around for NASA to build a colony on the moon.

stutefish
2009-May-20, 10:55 PM
It's not a matter of running short on resources, it a matter of we are screwing up our planet while we are mining those resources. If we rip apart an asteroid, it's not going to kill our marine life, damage an ecology region or require cutting down a rain forest. Not only that, why do we have to suck our planet dry of resources when there are billions of tons of the stuff floating around near by.
You're overlooking the major problem we have right now: None of those tons of stuff will yield even remotely enough resources to cover the resource costs of getting them.

We'd have to screw our planet up even more, putting together the machinery and infrastructure and energy stockpiles necessary to mine an asteroid. By the time we were done, even counting the resources we'd gotten from the asteroid, we'd have less resources than we started with. In effect, we do more every day to save our environment by not mining asteroids , than we could ever hope to do by mining them.

That's the real reason we're not mining asteroids: It's literally not profitable.

There are two scenarios I can think of, that would justify the expense of mining an asteroid: One is, that we are running so short of terrestrial resources, that our very survival depends on doing so, and no price is too high to pay. The other is, that some epic advance in applied engineering technology has so reduced the resource costs of mining asteroids, that doing so will yield a resource profit.

Ara Pacis
2009-May-20, 11:27 PM
Yes, short term some companies can make some money on the entertainment aspects, but as more companies get into the business the value is going to drop. Which is good for people like us who can't afford the millions to go up for a ride. Long term however the money is going to be in the resource collection and aspects around it. I can foresee ship building companies making the equipment, mining companies buying the ships to use in the mining, transport companies for hauling the resources and people, etc, etc, etc. Commerce is what drives our society and it's going to be commerce that gets us out into space faster than waiting around for NASA to build a colony on the moon.

There's more to the "entertainment" category of commerce than joyriding. You have cinema (as in location shoots), tele-robotic tele-exploration, sales of novel merchandise from space, and theme parks in space if you want to build a large station (as well as the vice industry of gambling and other adult entertainment that would find novel application in microgravity). There are other industries besides entertainment as well.

raptorthang
2009-May-21, 12:26 AM
As a geologist I can asure you that we are not even remotely in danger of running out of any mineral resource. Hundreds of mines around the world are closed because of the cost of operating and not because of any lack of resource. Thousands of other potential mine sites are not developed...again because not profitable.

There is no profit in mining an asteroid. The product is not necesary. Perhaps 'some day' in the distant future there might be a reason to spend billions and billions in infrastructure to exploit an asteroid's resource but the scenario where it would be practical is difficult to come up with. Even as a precious metal, asteroid mining is not feasible. for example the world's 2500 or so ton annual production of gold is a fraction that can be mined on Earth and any product brought in from an asteroid would just deflate the value and be self-defeating as an enterprise.

Ara Pacis
2009-May-21, 06:26 AM
You're overlooking the major problem we have right now: None of those tons of stuff will yield even remotely enough resources to cover the resource costs of getting them.Are referring to the commodities markets or the cost of propellant versus the price of whatever is "mined" in space or something else?


We'd have to screw our planet up even more, putting together the machinery and infrastructure and energy stockpiles necessary to mine an asteroid. By the time we were done, even counting the resources we'd gotten from the asteroid, we'd have less resources than we started with. In effect, we do more every day to save our environment by not mining asteroids , than we could ever hope to do by mining them.This sounds like reactionary hyperbole. Are you aware of how little cost space access currently is with regard to the global of even US GDP?


That's the real reason we're not mining asteroids: It's literally not profitable.Profitability depends on many variables that may not hold steady in the future. In case you haven't paid attention to the global markets lately, they fluctuate.


There are two scenarios I can think of, that would justify the expense of mining an asteroid: One is, that we are running so short of terrestrial resources, that our very survival depends on doing so, and no price is too high to pay. The other is, that some epic advance in applied engineering technology has so reduced the resource costs of mining asteroids, that doing so will yield a resource profit.One: there are a few minerals and elements which are rare or hard to find on the earth, like Lithium, which might be profitable if found in good supply out in space; howeover, the main issue may not be rarity of commodity minerals but ecological issues that make the "cost" of certain resources higher than their abundance on Earth might otherwise indicate. Moreover, the increasing costs of accessing harder to access minerals on earth might make space-based resource management more inviting. But then again, maybe it will work in reverse and instead of protecting the environment of Earth, we'll plunder the planet and grow food on space stations.

Two: do we need a breakthrough (I assume that's what you meant by "epic advance") in engineering to be able to mine asteroids? We currently have rockets that work and tools that work, so putting them together should be rather straightforward engineering.

Antice
2009-May-21, 06:45 AM
tools that work is a relative term. gravity assisted mining and refining is very different than having to do it in a zero-G environment. Mining is also a very manpower intensive endevour. while digging is done by machines they are all controlled by humans. it's a brainpower thing. not saying it cant be automated to a point where only 2 or 3 humans can mine an asteroid within a reasonable time frame. but the risks of loss of life is very high when dealing with this sort of thing. people die in mines even today.
same is true for construction. people get hurt in that business as regular as clockwork. It's the main reason why you dont want to have a whole load of people up there doing the work. it's safer to do it down here. also. people are high maintenance as well... so in order to take extensive use of them you need a lot of infrastructure. it becomes just another chicken and egg problem.
Start with easy to do stuff at first. like Lego block building modules. it's doable with tele-operaton today. then add whatever function makes sense at the time. sooner or later it might very well evolve into something akin to what you want. but it wont be soon

As for replacing the shuttles abilities. that is the whole point of the space gantry. it could fit on a single launch if you want. since it can be teleoperated from earth easily enough.with 2 launches you could add a basic service module for crew arriving in a capsule/whatever.
Strap on an ion engine and it could slowly move over to where you need it if it has to assist construction in some particular orbit. it needs engines to maintain orbit annyhow.

mahesh
2009-May-21, 07:44 AM
Damburger, excellent question posed at OP...
I apologise, I haven't diligently read all the BAUTzen's comments yet.
May I add, (...hastening to, he does) that a few moons ago, I read articles in the Astronomy magazine about NASA's research into using tethers in space.

I believe, there was, is, a Scottish company (no doubt, many others, elsewhere), manufacturing fishing nets, which was involved, providing material to make tethers, which were tested on the shuttles. Sorry, I do not have precise information (links-wise) on it, at the moment.

But, my tuppence worth.....here's :
http://www.iki.rssi.ru/mirrors/stern/Education/wtether.html
and http://www.tethers.com/

I would like to add my thanks, to my expert fellow-BAUTzens, for providing fascinating comments/reading.

aquitaine
2009-May-21, 02:03 PM
Again, however, this seems (to me) to be confusing mining, refining and production and construction as it is typically done here on Earth with how it might be done on such an asteroidal body.

A great deal of minerals will probably never be economically recoverable from diffuse undifferentiated asteroidal sources. Nor does it make sense to ship these elements in raw ore form from the bodies where they are extracted. But refined billets, rods and spools of wire or sheeting would make good sense and such can be easily processed into finished structural elements. As for the mining and processing, that depends upon the nature of the asteroidal ore and the types of elements one is seeking to recover. There are lots of such methods, though I seriously doubt if any of them would be deployed in Earth orbit. For the most part, anywhere within the Earth-Moon system, it is almost always going to be cheaper and easier to launch semi-refined and/or lightly manufactured materials from the surface of the Earth than it is going to be to recover, refine and process to the same point from extra-terrestrial sources. This is primarily do to the required infra structure for these additional steps, and the pre-existing mineral recovery and industrial base upon the Earth.

It is true that space industrialization does have a high initial cost because infrastructure needs to be setup, but once that is done I don't see it costing as much, assuming zero g refining and construction techniques are invented and improved.

I imagine it would work like this: Ore comes to the moon from the asteroid belt, the moon refines it either into usable materials for zero g construction or the precious metals would simply be seperated, those then get sent up either to lunar orbit or earth orbit to be used for various zero g construction (space stations, ships, etc). Some of the precious metals might get used for construction, but the majority of it would be sent back to Earth. Earth sends back needed supplies (parts, people, food) to both luna and the asteroid "mines".

rommel543
2009-May-21, 03:44 PM
It is true that space industrialization does have a high initial cost because infrastructure needs to be setup, but once that is done I don't see it costing as much, assuming zero g refining and construction techniques are invented and improved.

I imagine it would work like this: Ore comes to the moon from the asteroid belt, the moon refines it either into usable materials for zero g construction or the precious metals would simply be seperated, those then get sent up either to lunar orbit or earth orbit to be used for various zero g construction (space stations, ships, etc). Some of the precious metals might get used for construction, but the majority of it would be sent back to Earth. Earth sends back needed supplies (parts, people, food) to both luna and the asteroid "mines".

This is pretty much the same that I'm thinking. Yes the initial infrastructure is going to be costly but what industry isn't that way. Once the infrastructure is set-up and running, there are far more resources in space than there are on earth so you don't have to worry about a mine shutting down due to the ore running out. Also the wear and tear on the machinery here due to weather and gravity wouldn't exists in space (although on the moon you have to worry about the regolith).

Also I never said that we were running low on minerals and resources on earth (although we will be running out of oil in the not to distant future). We could strip mine the entire planet, suck every last resource from the ground but what is that going to leave us? A chewed up dead planet that can't support life anymore. No I'm not under the preconception that we could actually use up an entire planet worth of material.

Mining asteroids also has a side benefit. It helps clear out the near earth orbiters and decreases the chance of impacts. If something were to come at use from deep space, send out 2 or 3 mining crews that could chew it up and haul back the ore. Instead of looking at these as deadly missiles, we could look at them as home delivered resources.

Also I am not under the impression that we can start doing this today. There are numerous issues that need to be overcome. Cosmic and solar radiation once you get out of the protective magnetic field, engines that produce enough force without having to load your cargo bays full of fuel, increasing the speed of crafts in space, with a suitable ability to slow down once you get to your destination (a sling shot method to get between asteroids isn't going to work). I'm not aware how many companies are actually looking into these issues, but if we got a bunch of private industry companies working on these issues we could knock them off pretty quick.

samkent
2009-May-21, 05:57 PM
Oh please come back to earth with us! This has gone from a dream to someone’s fantasy.

The longest train ever used 682 cars carrying iron ore. Smaller trains run daily and you expect we can get this kind of volume from space? With what kind of booster do you propose to move that much around the solar system? We can’t even lift one of those cars into LEO but you think we will be able to move many orders of magnitude more from Mars orbit back to Earth? And then de-orbit train load after train load? Where do you plan to get that much energy??

How much would a ounce of asteroid gold cost to mine-refine-transport back to Earth?
What person in the know says we will need to do any of this?

rommel543
2009-May-21, 06:29 PM
Oh please come back to earth with us! This has gone from a dream to someoneís fantasy.

The longest train ever used 682 cars carrying iron ore. Smaller trains run daily and you expect we can get this kind of volume from space? With what kind of booster do you propose to move that much around the solar system? We canít even lift one of those cars into LEO but you think we will be able to move many orders of magnitude more from Mars orbit back to Earth? And then de-orbit train load after train load? Where do you plan to get that much energy??

How much would a ounce of asteroid gold cost to mine-refine-transport back to Earth?

Honestly your entire comment says we should stop the entire space program. What purpose does it hold. Putting a man on the moon, impossible its too far away. Sending a craft outside our solar system, what a fantasy. But we're already done these things. Too often these days fantasy becomes reality.

As I already mentioned we don't have the technology to do this, it would need to be created. I get the physics behind the acceleration and deceleration required to move a body in space. I get the idea that if you have X amount of weight you need Y amount of energy to get it moving to a specific speed. My point, which I've made multiple times, is that we need private companies getting into the space age to get these technologies off the ground. Pretty much all of our technology we have today started out with these huge expensive pieces of machinery, but because of private companies competing with each other they've become smaller, better and cost less. If you had car companies making space craft instead, everyone could vacation on the moon (I'm exaggerating here).


What person in the know says we will need to do any of this?
I just have to quote someone else in response to this. In 1977 Ken Olson, a US computer engineer and the president of Digital Equipment stated "There is no reason for any individual to have a computer in his home.". He was, as you commented, someone in the know.

Trantor
2009-May-21, 07:12 PM
I think that the use of small asteroids for bases and for manufactoring is something that will take place after we develop more advanced space operations technologies. An asteroid makes perfect sense for establishing a base because it's already located in space, it's made of metals that can be used for building/manufactoring, and it may be small enough that it can have some mobility. Tunneling inside to make living and working areas also offer excellent protection from the hostile space environment.

I think this is not going to happen within the next 50 years, but perhaps in the next century, our space operations technologies and expertise will allow us to do it. I agree that Ceres would be a good place for a base farther out in the Solar System, but a small asteroid base located between the Earth and the Moon would work well as a zero or very low gravity base of operations, where manufactoring and assembly work could also take place.

Antice
2009-May-21, 07:14 PM
mining to bring back to earth for use is just a big waste. there is rely nothing out there we really lack here. if we go it's going to be because we want to expand. not bring back stuff we already have.
science is the driver of the space frontier. not greed like in the olden times. altho i have to say. science is a lot nobler goal, Albeit a lot slower one.

Trantor
2009-May-21, 07:29 PM
I don't think that mining asteroids to bring back raw materials to the Earth makes sense either. Most likely, asteroid mining will take place in order to build right there or to make living and working areas inside the asteroid. You could make a very nice space hotel, in addition to a factory or a spaceport.

stutefish
2009-May-21, 08:35 PM
Are referring to the commodities markets or the cost of propellant versus the price of whatever is "mined" in space or something else?
The revenue generated by mining an asteroid is currently estimated by the market to be substantially less than the capital investment necessary to mine the asteroid.

If this were not the case, somebody would be profiting from it right now.


This sounds like reactionary hyperbole. Are you aware of how little cost space access currently is with regard to the global of even US GDP?
It's not a question of how much space access costs compared to overall GDP. It's a question of how much space access costs compared to how much revenue it generates.

And while some space access does, in fact generate revenue greater than its costs, it's pretty clear that nobody in the space access business thinks that the revenue generated by mining an asteroid would be greater than the costs of accessing it.

If you insist on thinking of it in terms of a percentage of the GDP, then do it right: Instead of considering the cost of putting a communications satellite into LEO, consider the cost of getting a mining apparatus to the asteroid belt, mining the asteroid, getting the raw materials back to Earth, and delivering them to a factory for additional processing.

I mean, there's already resources right here on Earth that we don't bother mining, because it's not profitable.


Profitability depends on many variables that may not hold steady in the future. In case you haven't paid attention to the global markets lately, they fluctuate.
And when they fluctuate to the point where mining asteroids yields more resources than it consumes, the global markets will start investing in it.


One: there are a few minerals and elements which are rare or hard to find on the earth, like Lithium, which might be profitable if found in good supply out in space; howeover, the main issue may not be rarity of commodity minerals but ecological issues that make the "cost" of certain resources higher than their abundance on Earth might otherwise indicate. Moreover, the increasing costs of accessing harder to access minerals on earth might make space-based resource management more inviting.
I'm pretty sure this is exactly my point.


But then again, maybe it will work in reverse and instead of protecting the environment of Earth, we'll plunder the planet and grow food on space stations.
Maybe so.


Two: do we need a breakthrough (I assume that's what you meant by "epic advance") in engineering to be able to mine asteroids? We currently have rockets that work and tools that work, so putting them together should be rather straightforward engineering.
Are you sure about this?


How much rocket fuel would you need, to get your tools (assuming they really do "work") to an asteroid?
How much rocket fuel would you need to alter the velocity of the asteroid's mass, to bring it back to Earth?
How much rocket fuel would you need, to alter the velocity of the asteroid's mass, to slow it down to a workable reentry speed?
How much of the asteroid's mass would you write off as an acceptable loss during reentry?
Alternatively, how much heat shield will you invest in, to protect your valuable asteroid material from ablation during reentry?
Going back to rocket fuel, do rockets with that much capacity currently exist?
If not, has anything in the history of human space flight so far caused you to believe that developing new rocket types--especially record-breaking new heavy lift types--is "rather straightforward engineering"?
And it would be a record-breaking new heavy lift type. Consider how much lunar material each Apollo mission brought back. Even if you replace the humans with robots, and leave them behind when you return, surely you'll want a larger return payload, yes? The entire mass of the Apollo Ascent Module was only a tiny fraction of the total payload mass of the Saturn V stack. The Saturn V stack is still the heaviest launch vehicle ever built, and all it had to do was bring a couple tons back from the Moon.
How much asteroid mass would you need to bring back, to be sold at what prices on the commodities market, to pay for all that rocket fuel, all those tools, and all that R&D on your new rocket type?
Alternately, if you plan to keep your tools so you can re-use them, you'll need to return less asteroid material, or buy more fuel, or both.
In fact, you'll need to buy a lot more fuel, to move those tools from one job site to another anyway.
How many resources will you have to consume here on Earth, building that rocket, processing and storing that rocket fuel, etc. More resources than you're getting back from the asteroid? How many tons of asteroidal iron ore would it take to pay for each ton of titanium in your rocket chassis?
And what will be the impact to the Earth environment, of all your resource-extraction and processing? How many tons of asteroid-resources will you need to bring back, to offset the damage to the environment of each ton of terrestrial resources you extracted to get there in the first place?


These are the kinds of things I think about, when I think about whether asteroid-mining is profitable or not.

If you think the current commodities market could make such an endeavor profitable, I'm sure Boeing's for-profit space access division would be very eager to invest in your business plan.

Also, I'm curious about these "tools that work". What did you have in mind?

Most mining equipment on Earth makes extensive use of our planet's substantial gravity field. Drills brace their considerable mass against the planet, in order to deliver the necessary force to their work surface. Conveyor belts rely on gravity to keep the extracted material on track to transportation and processing points. Indeed, gravity does an excellent job of collecting all the "spillage" in a nice neat pile downhill from the tool. Bucket loaders and backhoes rely on gravity to keep their materials in nice workable lumps. And they rely on gravity to keep them from flying off in the opposite direction whenever they bring their tools into contact with their work surfaces.

So the first thing you'll have to do is come up with a set of tools that don't rely on gravity to do their jobs.

The second thing you'll have to do is compensate for the fact that when these tools break--as they surely will--you won't have the luxury of a mechanic on-site, to repair the tool casually in a shirt-sleeve environment. If you have a mechanic on-site at all, it'll be hideously expensive, and you'll have to factor that cost into your business plan as well. Alternatively, you could so thoroughly over-engineer your tools that they will have almost no chance of breaking. That would be another significant cost to consider. Or you could send out several sets of tools, relying on redundant spares to compensate for breakdowns. Again, it's costly.

That's what I think about, when I think about whether or not we have "tools that work" for asteroid mining.

Mind you, I'm not saying it can't be done. I think it can be done, and that sooner or later it will be done. I just think that the current technology, and the current demand, just isn't there, and that's why it's not being done currently.

If the technology becomes cheaper, or the demand goes up significantly, then asteroid mining will be that much closer to becoming a reality.

cjameshuff
2009-May-22, 12:47 AM
I don't think that mining asteroids to bring back raw materials to the Earth makes sense either. Most likely, asteroid mining will take place in order to build right there or to make living and working areas inside the asteroid. You could make a very nice space hotel, in addition to a factory or a spaceport.

There is some sense in it, though I suspect the moon would be more practical than asteroids, especially if water ice is found. Not stuff like iron...that's easy enough to get and refine on Earth. However, energy-intensive materials like aluminum...form it into a shape that can aerobrake and mostly survive atmospheric entry, and smash down into a collection zone somewhere. Semiconductors...low-mass, their production involving large amounts of energy and very environmentally unfriendly processes. Need a gentler landing, but not by that much, especially if already diced. Landing stuff like this on Earth is relatively easy, you don't need a soft landing...the problem's launching enough to establish the infrastructure needed to make it and the delivery vehicles. Those delivery vehicles don't need to be launched from Earth's surface, and so are not comparable in cost to anything that has been used. They can use relatively heavy and crude heat shields, for example, and get most of the delta-v needed to reach Earth's atmosphere on survivable trajectories from nuclear tug craft.

And something that's doable much sooner, delivery to Earth orbit: basalt fiber to form into composite spars and structural cables, aluminum tubing, simple photovoltaics...build solar power stations to ultimately deliver power to Earth.

On the economics, consider the implications of more stringent environmental protections. Doing things on Earth has costs too, in being forced to use less environmentally damaging but less efficient or effective industrial processes, and in energy costs. Some things we just accept as having no alternative. It is more expensive in the short term to do large scale production in space, but how expensive is it in the long run to continue to do it all on Earth?

aquitaine
2009-May-22, 01:24 AM
Cosmic and solar radiation once you get out of the protective magnetic field, engines that produce enough force without having to load your cargo bays full of fuel, increasing the speed of crafts in space, with a suitable ability to slow down once you get to your destination (a sling shot method to get between asteroids isn't going to work).

The first one has more or less been solved by creating our own magnetic field as well as that radiation blanket that was mentioned on universe today. The second issue is really where nuclear rockets would shine.


The longest train ever used 682 cars carrying iron ore. Smaller trains run daily and you expect we can get this kind of volume from space? With what kind of booster do you propose to move that much around the solar system? We can’t even lift one of those cars into LEO but you think we will be able to move many orders of magnitude more from Mars orbit back to Earth? And then de-orbit train load after train load? Where do you plan to get that much energy??

Like I said, most of the material would not go back to earth, it would be used in orbit. The entire point of this is not because the Earth is running out of resources, but because building things in space is much easier and cheaper when your materials already come from a zero g source. Only the leftover precious metals like platinum would go back because their value makes the whole excercise worth it.

stutefish
2009-May-22, 02:54 AM
Like I said, most of the material would not go back to earth, it would be used in orbit. The entire point of this is not because the Earth is running out of resources, but because building things in space is much easier and cheaper when your materials already come from a zero g source. Only the leftover precious metals like platinum would go back because their value makes the whole excercise worth it.
If the resources aren't coming back from space, then you'll need to develop not just space-based mining facilities, but space-based processing facilities, space-based manufacturing facilities, and space-based assembly and finishing facilities.

Unless I'm gravely mistaken, it'd be cheaper just to mine, process, manufacture, and do at least some of the assembly right here on Earth, and have the actual spacecraft or whatever your end goal is for a fraction of the cost required to build all these facilities in space.

I mean, I can see some value in having an orbital assembly yard, for final assembly and finishing. But you don't need to set up a whole asteroid-mining infrastructure for that...

aquitaine
2009-May-22, 04:20 AM
If the resources aren't coming back from space, then you'll need to develop not just space-based mining facilities, but space-based processing facilities, space-based manufacturing facilities, and space-based assembly and finishing facilities.

Isn't that what I implied?


Unless I'm gravely mistaken, it'd be cheaper just to mine, process, manufacture, and do at least some of the assembly right here on Earth, and have the actual spacecraft or whatever your end goal is for a fraction of the cost required to build all these facilities in space.

Earth has a huge gravity well. Short term perhaps it is cheaper because of initial infrastructure costs, but long term most certainly not. Plus this puts a big brake on how large you can scale things. One of the biggest limiting factors to the ISS and everything else we've ever put up is the limited amount of mass we can carry with us on each rocket ride (which can cost hundreds of millions of dollars each). With these constraints removed, we can build things that are bigger, better, and more functional that what we have today.

Antice
2009-May-22, 04:21 AM
Launching from earth is expensive. but it's still cheaper than mining asteroids.
besides big projects would need lots of launches. thus enabling economy of scale as well.
a common miss conception it seems is that spacecraft that is reused in space works for free once initial investment is paid off. that is just not true. you still need human oversight. not to mention that there is a multi billion dollar investment involved in designing each new craft.

Ara Pacis
2009-May-22, 04:29 AM
response part 1.

The revenue generated by mining an asteroid is currently estimated by the market to be substantially less than the capital investment necessary to mine the asteroid.

If this were not the case, somebody would be profiting from it right now.Okay, that's what I thought you meant. Ah, but I wasn't referring to pure market profitability. As I've said all along, other issues, such as environmental concerns, may be the important factor. When I studied regulation regimes in college, we read of Robert Kagan's theory of the Licence to Operate, which involves three licenses: Commercial Licence (market profitability); Regulatory License (government mandates), and; the Social License (the popular support for or against certain practices). One example was a paper mill that tried to use a less environmentally damaging chemical in it's manufacturing process, but it cost a bit more and their paper cost a bit more so their profitability was less and they eventually switched back to the older more environmentally dangerous practices. Howeover, if government regulations had gone through and been approved, all the other mills would have had to comply and start using that new process, which would have cost them more, but would have been less problem for the market because all the manufacturers had the same requirement. So, their profitability would have stayed on par with each other, even if the cost of the product increased industrywide. The social license was also important in dumping practices at one mill where the local population demanded it, but another plant was able to get away with dumping because it was out in the wilderness. Howeover, due to the interaction of the local population (some of whom were employees) and environmental NGOs, the company realized that aquiescing to demands was better and less costly than fighting it.

So, the strict calculus of profit may need to include such considerations. Governments may increase fines, fees, and costly requirements for environmental degradations. Governments might also partially subsidize space-based mining and manufacturing through direct financing or tax-breaks and other mechanisms. Even if some space-mined materials are still more expensive, people may be willing to pay extra for them or products made from them.



It's not a question of how much space access costs compared to overall GDP. It's a question of how much space access costs compared to how much revenue it generates. I was addressing a different argument here. You were saying that we would do more damage to our environment by attempting space-mining and my response was that the current cost of space-access, as a fraction of all the other endeavors in our economy, is rather miniscule. Even increasing space-access expenditures several times over would be a drop in the bucket with regards to human economic activity that may be environmentaly damaging.


And while some space access does, in fact generate revenue greater than its costs, it's pretty clear that nobody in the space access business thinks that the revenue generated by mining an asteroid would be greater than the costs of accessing it.In the current space-access paradigm, I would agree. But I'm also not short-sighted enough to think that such things must remain that way.


If you insist on thinking of it in terms of a percentage of the GDP, then do it right: Instead of considering the cost of putting a communications satellite into LEO, consider the cost of getting a mining apparatus to the asteroid belt, mining the asteroid, getting the raw materials back to Earth, and delivering them to a factory for additional processing. Such an estimation would be guesswork at this point and makes assumptions I am not suggesting. I'm not strictly referring to asteroids when I write of space-based mining, nor am I referring to bringing raw materials back to earth for additional processing. I was thinking mainly of specific resources on the moon, like aluminum, and the possibility of finding rare elements in abundance in some asteroids (or the moon or mars) that might make retrieving them simple and straight-forward. Some of the material might be used for space projects and save the hassle of lifting them from Earth, but some of the rarer elements might be sent to Earth.


I mean, there's already resources right here on Earth that we don't bother mining, because it's not profitable. And why is that? Is it because the element is cheap because no one uses it? Is it because the mineral is of a low concentration at those particular mines? Is it because energy needed for processing is to costly? Aluminum smelting was one of the major uses of the hydroelectric power of the Grand Coulee Dam when it was first completed. With a lot of sunshine in our vicinity in space, that natural power and/or heat can be used at relatively low operating costs to run processing plants in space.



And when they fluctuate to the point where mining asteroids yields more resources than it consumes, the global markets will start investing in it.Again, you mention consumption of resources instead of cost, which I questioned above in my last response. Are you referring to specific masses of specific elements? Some materials are more useful and/or more abundant than others, so expending a lot of a plentiful element while retrieving a rarer element is not necessarily a bad calculation.



I'm pretty sure this is exactly my point.Then why are we arguing?


Are you sure about this?Pretty much. but maybe I have a different definition of straight-forward engineering than you do.

Ara Pacis
2009-May-22, 04:36 AM
response part 2

How much rocket fuel would you need, to get your tools (assuming they really do "work") to an asteroid?Depends on the propulsion method.

How much rocket fuel would you need to alter the velocity of the asteroid's mass, to bring it back to Earth?Why would I bring a whole asteroid back to earth? It might be broken into chunks and sent on the Interplanetary Transport Network to a non-terestrial collection site. An electromagnetic catapult might be used here, as might laser pulse propulsion.

How much rocket fuel would you need, to alter the velocity of the asteroid's mass, to slow it down to a workable reentry speed?
How much of the asteroid's mass would you write off as an acceptable loss during reentry?
Alternatively, how much heat shield will you invest in, to protect your valuable asteroid material from ablation during reentry?I wouldn't send an asteroid on a re-entry trajectory. But assuming that some of the material might eventually make it's way to Earth's surface as processed material, I would prefer that it enter using retrorockets and hypersonic waverider-type craft. This would be a generic spaceflight issue and not just an issue for space mining. If we plan to have any long-term presence in space, whether for science or commercial industries of any sort, it would behoove the governments/companies to solve such issues for their own sakes.


Going back to rocket fuel, do rockets with that much capacity currently exist?
If not, has anything in the history of human space flight so far caused you to believe that developing new rocket types--especially record-breaking new heavy lift types--is "rather straightforward engineering"?
And it would be a record-breaking new heavy lift type. Consider how much lunar material each Apollo mission brought back. Even if you replace the humans with robots, and leave them behind when you return, surely you'll want a larger return payload, yes? The entire mass of the Apollo Ascent Module was only a tiny fraction of the total payload mass of the Saturn V stack. The Saturn V stack is still the heaviest launch vehicle ever built, and all it had to do was bring a couple tons back from the Moon.I think you answered your own question about launchers existing or suggesting that they could. Others might argue that SeaDragon and von Braun's mars mission designs are examples of straightforward engineering if not considered extant designs. But why insist in new superhuge rockets? With even basic assembly in space, multiple launches of current rockets could be used to lift the necessary total mass. Multiple launches would also likely have the benefit of lower costs due to economy of scale.


How much asteroid mass would you need to bring back, to be sold at what prices on the commodities market, to pay for all that rocket fuel, all those tools, and all that R&D on your new rocket type?What new rocket type? Commodity prices would depend on the commodities markets and may or may not include additional costs and subsidies based on place of origin, but once it hits the actual markets, it just becomes part of the global supply.

Alternately, if you plan to keep your tools so you can re-use them, you'll need to return less asteroid material, or buy more fuel, or both.
In fact, you'll need to buy a lot more fuel, to move those tools from one job site to another anyway.Yeah, maybe, it may be a case by case basis as to whether the tools are reused or abandoned or converted to some other use, perhaps for science.

How many resources will you have to consume here on Earth, building that rocket, processing and storing that rocket fuel, etc. More resources than you're getting back from the asteroid? How many tons of asteroidal iron ore would it take to pay for each ton of titanium in your rocket chassis?It depends on the price and any subsidies that need to be applied. And why base the argument on iron? There are other elements that would be much more lucrative than iron. And why assume that the rocket chassis is titanium, but assuming it has some, why assume that it is consumed? Recycling would minimize the resource "usage".

And what will be the impact to the Earth environment, of all your resource-extraction and processing? How many tons of asteroid-resources will you need to bring back, to offset the damage to the environment of each ton of terrestrial resources you extracted to get there in the first place?That's a spurious argument. As I have mentioned before, the GDP (or if you prefer another term, the total economic mineral economy of the world) is a lot larger than the rockets would use. Much of the terrestrial mining will continue for other reasons not related to rocketry. Some of the material in rockets may be recycled, go back into the material stream of the global mineral market to be used somewhere else, perhaps even in rockets. Higher usage and prics of aluminum might make recycling of beverage containers more common as well and may provide a net benefit to the environment.



These are the kinds of things I think about, when I think about whether asteroid-mining is profitable or not.Well, it's a start, but finding answers is as important as formulating the questions.


If you think the current commodities market could make such an endeavor profitable, I'm sure Boeing's for-profit space access division would be very eager to invest in your business plan.I don't recall saying "current commodities market". The cost dynamic of such an endeavor has many variables of which commodity prices is only one. Lower cost for space access would be an important variable and that need not be predicated on new technology. Mass production and utilization of rockets would do more to lower the price of any space endeavor than almost any other variable.


Also, I'm curious about these "tools that work". What did you have in mind?

Most mining equipment on Earth makes extensive use of our planet's substantial gravity field. Drills brace their considerable mass against the planet, in order to deliver the necessary force to their work surface. Conveyor belts rely on gravity to keep the extracted material on track to transportation and processing points. Indeed, gravity does an excellent job of collecting all the "spillage" in a nice neat pile downhill from the tool. Bucket loaders and backhoes rely on gravity to keep their materials in nice workable lumps. And they rely on gravity to keep them from flying off in the opposite direction whenever they bring their tools into contact with their work surfaces.

So the first thing you'll have to do is come up with a set of tools that don't rely on gravity to do their jobs.Guy wires. Tension cables will hold tools down onto the surface and absorb shocks and opposite reactions. That's probably enough for basic rock busting on asteroids, and if it's on the moon then you do have significant gravity. Mesh nets can be used to hold rocks from flying apart.

Bucket loaders and backhoes do use gravity, but they are used in order to deal with the problems of gravity. If you feel the need to put something in a container in space, then simply put a lid on it. If you simply must use a conveyor belt in space, and I'm not sure why you would, then use lidded buckets for small stuff and a two belts to hold bigger things between them, or a tube with paddles on a chain to push things through it.


The second thing you'll have to do is compensate for the fact that when these tools break--as they surely will--you won't have the luxury of a mechanic on-site, to repair the tool casually in a shirt-sleeve environment. If you have a mechanic on-site at all, it'll be hideously expensive, and you'll have to factor that cost into your business plan as well. Alternatively, you could so thoroughly over-engineer your tools that they will have almost no chance of breaking. That would be another significant cost to consider. Or you could send out several sets of tools, relying on redundant spares to compensate for breakdowns. Again, it's costly.The cost would in the delta-v of the mass not in any inherent cost of the tools. Most of the tools would be pretty basic for long-range missions. If the asteroid material is sent to a central location for processing then tool spares for more complex machines isn't much of an issue.


That's what I think about, when I think about whether or not we have "tools that work" for asteroid mining.Well, you're not thinking like me, which is probably why you haven't arrived at the same conclusions.


Mind you, I'm not saying it can't be done. I think it can be done, and that sooner or later it will be done. I just think that the current technology, and the current demand, just isn't there, and that's why it's not being done currently.

If the technology becomes cheaper, or the demand goes up significantly, then asteroid mining will be that much closer to becoming a reality.Which has been my point. The difference may be that I think it can be done with a suitable application of current technology. I think that current demand is there for certain minerals if we can find them out there. I know people talk about "an asteroid of gold" but there are minerals that are in high demand whose rarity makes their price and need far exceed that of gold. In some cases, I suspect some markets could not be glutted as the lack of enough of certain elements has prevented such markets from materializing despite research advances in the use of such materials.

publiusr
2009-May-22, 05:27 PM
I don't mind taking an asteroid to Earth

I was thinking about having a more or less solid asteroid (rotating) sliced Kursk style by cables. The rotating asteroid becomes a bola. One end of the bola is released and half of it comes our way. This would then be halved again and a second bola made. The end of the bola deposits directly upon Earths surface rotating back against its forward direction.

The tether deposits the hunk down in one piece.

Repeat.

No need for mining ships--just cutter/tethers loop ships and a lot of time.

aquitaine
2009-May-23, 01:36 AM
Launching from earth is expensive. but it's still cheaper than mining asteroids.
besides big projects would need lots of launches. thus enabling economy of scale as well.
a common miss conception it seems is that spacecraft that is reused in space works for free once initial investment is paid off. that is just not true. you still need human oversight. not to mention that there is a multi billion dollar investment involved in designing each new craft.


True they need maintenance, but the space shuttle costs $500 million to be launched just once. Once it is there, the facility would cost far less to be maintained than to launch the shuttle even once.

EDIT:
But how much will it cost to get there, land and eventually mine these heavenly bodies?

Benson said the cost would be under $50 million, about $200 million less than an asteroid mission designed and launched by NASA.

University of Arizona’

Source (http://www.space.com/businesstechnology/business/asteroid_mining_000210.html)

So to go there and mine the stuff would cost $450 million less than to launch the shuttle just once.

EDIT2: I just found this from a website that actually goes into all of this stuff (http://www.tricitiesnet.com/donsastronomy/mining.html)


Cost! The Earth's gravity makes sending stuff up into space and into orbit VERY expensive. Even a 1 kg. bag of sand would currently cost about $12,000 ($12 million per metric ton) to put into space on a shuttle flight. With space commercialization and more efficient space vehicles being developed, this cost is expected to drop dramatically. However, one shouldn't expect the cost to drop to much less than about $2,000 per kilogram ($2 million per metric ton). One of the main materials needed in space-based construction (such as for the International Space Station) will be Iron, in the form of Steel. On Earth, Iron sells for about $410 per metric ton. Carrying it into space will increase its cost to at least $2,000,410 per metric ton. That makes for one VERY expensive space station.

The cost of transporting material from one space-based location (asteroid mining/refining facility) to another (moon base, space station, etc. in geosynchronous Orbit) is only a tiny fraction of the cost of transporting it from Earth. An initial firing of engines for speed and direction, a few minor firings for navigational corrections, and another firing for orbiting, docking and/or landing is all that's required. And the size (weight) of the payload is of very little significance as well. In near-zero gravity everything weighs MUCH less (almost nothing). Once momentum is established, there is little gravity and friction to slow a craft down. It just keeps going.

Of course, the initial equipment needed to mine and refine asteroids will probably need to be brought from Earth. And this material WILL cost over $2,000,000 per metric ton. And other things such as food, clothing, water, oxygen, plastics, etc. will also need to be brought from Earth ... at least initially. Please see the PERMANENT website for information on how most of these things will eventually be produced in space or on the moon.

So, as you can see, despite the initial high cost of starting an asteroid mining operation, such a venture should easily become profitable in a very short period of time. As long as humans are committed to utilizing and exploring space there will be a market for asteroid products. And as long as the cost of these products are kept reasonable, a thriving and profitable market for refined elements and minerals, and products made from these materials, will exist.
An Asteroid Mining Operation

A large strip-mining operation on Earth can extract and process as much as 80,000 metric tons of ore per day (based on 2 10-hour shifts). It is easily possible to more than double this output with an asteroid mining operation. Many factors contribute to the ease of asteroid mining and refining, including the near-zero gravity environment in space, the abundance of cheap (solar) power, the abundance of free metal within the ore, and the "crumbly" nature of a typical C-Type asteroid.

There are 22 metallic elements present in C-Type asteroids which exceed (sometimes to an astonishing degree) the percentages found in the Earth's crust. And nearly all of them are important and/or scarce on Earth. They range from Copper (about 1.5 X Earth Crust Abundance (ECA)), to Platinum (27 X ECA), to Tellurium (2100 X ECA). These metals are of vital interest, both on Earth and in space, for manufacturing and more. Of course, the other 56 elements in our asteroid are also important. In fact, one would be hard pressed to find a comparably rich ore on Earth; especially one with such uniformity of composition and ease of benefication.

Since a majority of an asteroid mining operation would be automated, such an operation could run 24 hours a day, 7 days a week. Even accounting for a 20% down time for maintenance, setup, etc., such an operation should be able to easily process 50 million M.T. of ore per year. If all ore was processed and reduced to element form, 50 million M.T. per year works out to over $40 billion per year in element value. For a breakdown of all element's values based on 50 million metric tons per year output, please check out our OTHER CHART.

Of course, many of the elements in our asteroid will probably not be fully processed. For example, it is highly unlikely that all of the Oxygen present on an asteroid would be reduced out of its parent minerals. Most of the Silica (SiO2), which is a major oxygen-bearing mineral in asteroids, will probably be used "as is" for things like cosmic ray shielding (slag), ceramics, glass, fiberglass, concrete, and more. Magnesium (about 36% of ore value) has some use as an alloy in Aluminum and Steel, but its compounds (especially MgO) will be much more commonly used (shielding, bricks, etc.), and are much cheaper. Also, Scandium (about 10% of ore value) has very few uses at this time, thus a very small market. Finally, for exported (to Earth) metals, the metals market is subject to significant price fluctuations, and a sudden influx of one or more metals would probably have a moderate to significant effect on market prices.

On the other hand, most of the elements extracted would be used almost exclusively for space-based projects, such as for building space stations and bases, life support, rocket fuel, ships, satellites, manufacturing, etc. Probably only the precious metals and rare-earths would be suitable for export to Earth. Any element valued at $500,000 per M.T. ($500 per kg. or about $227.50 per lb.) or more (22 elements) would be a likely candidate for export to Earth. These elements represent about $100. per metric ton of ore in value. Based on our 50 million metric tons per year, this would represent about $5 billion per year in exportable metals. However, perhaps half of this production will be needed for space-based manufacturing. If this is the case, about $2.5 billion in exportable metals per year would be a more accurate figure.

Income from the export of precious/rare-earth metals should easily pay for the purchase and transport of any materials needed from Earth. Income from space-based sales would pay for expansion of mining operations, pay salaries of employees, and should generate substantial profit for investors.

samkent
2009-May-23, 02:52 AM
Aluminum smelting was one of the major uses of the hydroelectric power of the Grand Coulee Dam when it was first completed. With a lot of sunshine in our vicinity in space, that natural power and/or heat can be used at relatively low operating costs to run processing plants in space.


Please get some real figures behind your dreams. Look at the price of the solar panels alone.

http://industry.bnet.com/energy/1000857/fun-facts-on-the-international-space-stations-new-solar-panels/

Inflation adjusted, the total is about $550 million today.

Thatís for less power than 2 average US houses can pull from the power grid.
How much aluminum can you produce for that puny wattage?

Easy 15kwh per kilogram. Times 24 hrs gives you 72 kilograms per day. At the current price of $2.50 per kilo, $180 per day.
That means it will take you 8371 years just to pay for the solar panels.
Excuse me if my numbers are off a century or two.

Platinum is no better. We just donít need that much of it.

Do you still think mining off planet is remotely feasible?

cjameshuff
2009-May-23, 03:52 AM
Please get some real figures behind your dreams. Look at the price of the solar panels alone.

http://industry.bnet.com/energy/1000857/fun-facts-on-the-international-space-stations-new-solar-panels/

Inflation adjusted, the total is about $550 million today.

Thatís for less power than 2 average US houses can pull from the power grid.
How much aluminum can you produce for that puny wattage?

You're picking out one impractical way to do it and declaring the whole to be infeasible. Simpler, lower-tech solar panels produced from local materials could be made in vastly greater areas than those high-efficiency, ultra-light panels shipped up to the ISS at enormous cost per kg. Or the power may not even come from solar panels...it could be solar thermal, again using mirrors, boilers, turbines/stirling engines, and radiators produced from local materials. Your comparison to the ISS is completely meaningless.

Ara Pacis
2009-May-23, 01:40 PM
Please get some real figures behind your dreams. Look at the price of the solar panels alone.

What CJamesHuff said. I wasn't specifying solar PV. I think solar thermal will be utilized in several ways, both for producing electricity and for producing heat that is used directly in some processes.

Trakar
2009-May-23, 02:52 PM
It is true that space industrialization does have a high initial cost because infrastructure needs to be setup, but once that is done I don't see it costing as much, assuming zero g refining and construction techniques are invented and improved.


Eventualy, I'm sure you are correct. I imagine, however, that many if not most considerations of this issue have a strong tendency to underestimate the infrastructure scope and needs. Most especially many seem to forget to include "demand" as a major part of those infrastructure requirements.

Eventually I expect humanity and the entire human industrial base to regard the Earth and the Earth's industrial base as quite quaint and endearing, but that will be long after the majority of our species' population lives offworld, and I don't much expect that for several millenia, at the least.



I imagine it would work like this: Ore comes to the moon from the asteroid belt, the moon refines it either into usable materials for zero g construction or the precious metals would simply be seperated, those then get sent up either to lunar orbit or earth orbit to be used for various zero g construction (space stations, ships, etc). Some of the precious metals might get used for construction, but the majority of it would be sent back to Earth. Earth sends back needed supplies (parts, people, food) to both luna and the asteroid "mines".


The problem is going to revolve around two primary factors, one the cost to produce the product and the cost to transport the product to where it is utilized.

First, we need an offworld demand for materials and products, then we can look at what is the best way to meet that demand. Launch costs as well as production techniques are going to be driven as much, or more, by the nature of that demand as they are by the dreams, desires and innovations of concept advocates.

PraedSt
2009-May-23, 10:19 PM
I found this a few days ago. (Old event, reported recently.)

Europe, Russia to build LEO shipyard (http://www.flightglobal.com/articles/2009/05/20/326773/2025-leo-shipyard-is-new-esa-roscosmos-goal.html).


As far as I can make out, very early planning stage. But still; space docks! :)

cjameshuff
2009-May-23, 11:29 PM
First, we need an offworld demand for materials and products, then we can look at what is the best way to meet that demand. Launch costs as well as production techniques are going to be driven as much, or more, by the nature of that demand as they are by the dreams, desires and innovations of concept advocates.

Well, you need power to refine aluminum, lots of electrical power, solar power is the best bet in space. What else can you do with huge amounts of solar power? What's the biggest problem with solar power satellites? The cost of lifting the power generation machinery into orbit. If you're making huge amounts of power generation capacity in orbit already...

Refining semiconductors is also a very energy-intensive process that is difficult to make environmentally clean. Given the rate at which IC fabrication technology is progressing, it's probably not feasible to put advanced fabs in orbit and ship the finished products down, but you could drop ultra-pure silicon, germanium, etc down to Earth. Gallium-based semiconductors, too...gallium on Earth is largely produced as a byproduct of aluminum refining. Lunar ores might contain similar amounts, though the lack of the weathering processes that produce the ores we use on Earth makes this uncertain.

So, you have aluminum, ultra-pure semiconductors, and the power itself...if you can get sufficient infrastructure in place to construct even just the most mass-intensive portions of power generation equipment from local materials, there's plenty of use for it. And it's completely sustainable, massively scalable, and once established, near zero environmental impact. More expensive in the short term than leveling mountains for coal and burying the CO2, but far preferable...

My conception is a bit different than Aquitane's, though...if you've got processing facilities on the moon, they'll probably be running at capacity with lunar materials. Landing asteroid ores on the moon for processing sounds expensive, and energy availability is an issue...polar facilities can get full-time sunlight, but the large vertical collectors there would have to contend with gravity, albeit less than they would on Earth. It seems more feasible to perhaps put the first bootstrap facilities there, but in the long run to ship moderately-processed material from the moon to orbital refineries. Or perhaps a power station at the Earth-moon L1 point could supply more continuous power to the ground on the near side.

And yes, it requires very large amounts of infrastructure to get started, which is why I've suggested that limited Orion launches might not be a bad idea. Some people exaggerate the requirements, though...you don't need exotic aerospace alloys and ultra high precision machining. You can use much cruder machinery and materials when you're building it on the spot rather than shipping it at thousands of dollars per kg.

Trakar
2009-May-24, 12:18 AM
Well, you need power to refine aluminum, lots of electrical power, solar power is the best bet in space. What else can you do with huge amounts of solar power? What's the biggest problem with solar power satellites? The cost of lifting the power generation machinery into orbit. If you're making huge amounts of power generation capacity in orbit already...

Refining semiconductors is also a very energy-intensive process that is difficult to make environmentally clean. Given the rate at which IC fabrication technology is progressing, it's probably not feasible to put advanced fabs in orbit and ship the finished products down, but you could drop ultra-pure silicon, germanium, etc down to Earth. Gallium-based semiconductors, too...gallium on Earth is largely produced as a byproduct of aluminum refining. Lunar ores might contain similar amounts, though the lack of the weathering processes that produce the ores we use on Earth makes this uncertain.

So, you have aluminum, ultra-pure semiconductors, and the power itself...if you can get sufficient infrastructure in place to construct even just the most mass-intensive portions of power generation equipment from local materials, there's plenty of use for it. And it's completely sustainable, massively scalable, and once established, near zero environmental impact. More expensive in the short term than leveling mountains for coal and burying the CO2, but far preferable...

My conception is a bit different than Aquitane's, though...if you've got processing facilities on the moon, they'll probably be running at capacity with lunar materials. Landing asteroid ores on the moon for processing sounds expensive, and energy availability is an issue...polar facilities can get full-time sunlight, but the large vertical collectors there would have to contend with gravity, albeit less than they would on Earth. It seems more feasible to perhaps put the first bootstrap facilities there, but in the long run to ship moderately-processed material from the moon to orbital refineries. Or perhaps a power station at the Earth-moon L1 point could supply more continuous power to the ground on the near side.

And yes, it requires very large amounts of infrastructure to get started, which is why I've suggested that limited Orion launches might not be a bad idea. Some people exaggerate the requirements, though...you don't need exotic aerospace alloys and ultra high precision machining. You can use much cruder machinery and materials when you're building it on the spot rather than shipping it at thousands of dollars per kg.

Most of my comments upon your remarks would amount to quibbles and minor differences of opinion. Iused to argue much the same points and still feel that there is merit in them for many types of materials and products. However, the I have been met in the past with a counter argument that is hard to overcome. Most considerations of terrestrial manufacture versus ET manufacture revolve around lift costs from the Earth's surface. In many cases, merely lifting the infrastucture into place to allow adequate exploitation and industrial expansion into LEO and beyond, has the paradoxical effect of lowering launch costs to the point where it is generally cheaper and easier to utilize Earth-bound resources, industry and manufacturing rather than off-world resources and manufacturing, at least into the near future and within the Earth-Moon system. Once you have some major orbital colonies and extensive operations throughout the solar system this equation changes, but until then, out leveraging the sheer volume of our civilization's planetary surface industrial capacity is not easily done.

Antice
2009-May-24, 07:07 AM
Finally some sense. if you want to bootstrap space industry you have to make each step pay off dividends or at least in case of government programs make earth side benefits worth the costs.
Claiming that once it's in place in a hundred years time it will make massive profit wont bring investors. neither government nor private ones.
So how do you sell your dram then? as a dream? well that wont cut it either. nobody is going to shell out billions for a dream. So what then? well my take is that you need to create some sort of service that will be easy to sell. science experiments are one such service and it is the domain of the ISS currently. Orbital assembly and service is another. that is the forte of the shuttle. but not for long.
Now how can we do something along the path we want that would incorporate those 2 markets? Well. my take is to build a KISS space gantry. make it stupidly simple and sturdy. with the facilities needed to let any nation rent the capability for it's space program. design the gantry so that it fit's in one launch. once up there it can stay for a very long time between uses. heck. it can even sit on the ground waiting for the first customer. then be launched a few weeks prior to it's first task. make it able to dock with itself so that it can be expanded as well and you have the first cornerstone of something that can grow big over time.

added: well.. considering that Hubble would need another service run to keep going beyond it's current upgraded limit. such a structure could actually latch onto the Hubble to facilitate service missions trough Orion capsules as well. Might be some business there around 2015 or so....

Ara Pacis
2009-May-24, 09:03 AM
...polar facilities can get full-time sunlight, but the large vertical collectors there would have to contend with gravity, albeit less than they would on Earth. It seems more feasible to perhaps put the first bootstrap facilities there, but in the long run to ship moderately-processed material from the moon to orbital refineries. Or perhaps a power station at the Earth-moon L1 point could supply more continuous power to the ground on the near side.Or you could string two or three solar power facilities into an always-on circumlunar electrical distribution grid.


However, the I have been met in the past with a counter argument that is hard to overcome. Most considerations of terrestrial manufacture versus ET manufacture revolve around lift costs from the Earth's surface. In many cases, merely lifting the infrastucture into place to allow adequate exploitation and industrial expansion into LEO and beyond, has the paradoxical effect of lowering launch costs to the point where it is generally cheaper and easier to utilize Earth-bound resources, industry and manufacturing rather than off-world resources and manufacturing, at least into the near future and within the Earth-Moon system. Once you have some major orbital colonies and extensive operations throughout the solar system this equation changes, but until then, out leveraging the sheer volume of our civilization's planetary surface industrial capacity is not easily done.This is valid until it isn't. I would expect costs to fall dramatically, but they would plateau eventually. Moreover, large boosters are likely to still fall short of being able to lift certain items. I imagine that we might want to have tunnel boring machines on the moon and a large electromagnatic catapult on the moon and on a transit station in orbit. These would be massive constructions.

Now, some people may say we'll just continue to use rockets for lofting from the lunar surface and that we'll either use rockets for retro- de-orbit burns from LEO and/or take our chances with high-speed re-entry using tiles or other methods. However, I think that it might be advantageous to use something more robust and less finicky that does not place a mass and aerodynamic penalty upon a re-entering craft. Maybe someone will disagree and tell me it's a bad idea, but I think a several-km long catapult (Electromagnetic, or some other?) could be useful for de-orbit and inter-orbital accelerations of small taxi-craft and barges as well as serve as a base for commercial entertainment and industry as well as science endeavors. It would be simple in design, basically a large massive truss system, but would take a lot of material that might be more cheaply obtained from space based resources. As a project, it might drive enough interest to demand space resource utilization and jumpstart space mining.


Finally some sense. if you want to bootstrap space industry you have to make each step pay off dividends or at least in case of government programs make earth side benefits worth the costs.
Claiming that once it's in place in a hundred years time it will make massive profit wont bring investors. neither government nor private ones.
So how do you sell your dram then? as a dream? well that wont cut it either. nobody is going to shell out billions for a dream.I don't think that's necessarily going to be the case if you are referring to monetary dividends. Public interest might be enough of a reason, especially if tweaked properly. The Roman Catholic Church managed projects on decade and century scales, so it's possible to convince people to do such things.

As for shelling out a billion, you might consider many people shelling out lower amounts instead. Besides asking people to just donate, as if to a charity, a project might be funded with long-term bonds to individuals, and these bonds might have additional special benefits, like a piece of an asteroid or % off a future ticket or other novel gifts and coupons for affiliated purchases (like half off a movie ticket for the first cinematic feature filmed in space). They might use other types of fund-raising such as aluminum can recyling drives to be used as material for the rockets (albeit, nominally "used in rockets", as the material would be sold at scrap and probably put into the general supply and the capital used to fund operations and any other need, including purchase of aluminum parts). These would be in addition to other fund streams.

aquitaine
2009-May-26, 03:03 AM
The problem is going to revolve around two primary factors, one the cost to produce the product and the cost to transport the product to where it is utilized.


True that needs to be calculated, but something to be considered is that there is an enormous wealth of minerals in the asteroid belt, much of it concentrated. As has been said, there are billions of dollars worth of precious metals just on Eros, that alone makes the long term cost worth it.



First, we need an offworld demand for materials and products, then we can look at what is the best way to meet that demand. Launch costs as well as production techniques are going to be driven as much, or more, by the nature of that demand as they are by the dreams, desires and innovations of concept advocates.

There is already at least some demand for precious elements on world. In addition there is also the developing space tourism industry, amoung others which will grow in demand in the future.


Well, you need power to refine aluminum, lots of electrical power, solar power is the best bet in space.

Nuclear would still be a better option, it has much greater power density and efficiency.

cjameshuff
2009-May-26, 06:32 AM
Nuclear would still be a better option, it has much greater power density and efficiency.

Nuclear power requires nuclear fuel, which would need to be imported from Earth, while solar power can be harvested entirely or almost entirely using local materials. Mars may have had liquid water long enough to form useful uranium ore deposits as well, but is still far away in distance and delta-v and would require extensive mining and refining facilities there. My understanding is that uranium ores are hydrothermal deposits, and there's not likely to be rich uranium deposits in many other places. What's found may well take more energy to extract than the extracted uranium can provide.

The density of nuclear power is of great use for mobile spacecraft and for things like bootstrapping space based industry where there is not yet any local production capability of any kind, but it is not of great benefit to stationary facilities with effectively unlimited room. Those net energy-negative uranium sources mentioned above might be of use despite their energy cost, because solar power can be used to produce uranium for more mobile power demands.

Also, it's not sensible to compare it with solar power in terms of efficiency, since there is no fuel consumed in the operation of a solar power plant. What matters is power generation capacity, and for solar, you can make as much as you need, while nuclear power requires both more complex machinery and instrumentation that's more difficult to produce on the spot, and regular shipments of fuel. In any case, space-based solar thermal power is potentially just as efficient as space-based nuclear power, since there aren't the nightly interruptions that exist with ground based solar thermal. The hot side temperatures would be similar, and the radiator temperatures identical.

There's also less potential demand for orbital nuclear power plants. It doesn't make sense to beam power to the ground from such a plant when more power can be produced on the ground due to the availability of better heat sinks, and when the ground plant would be less easily serviced. So you'll get less use out of the machinery you lift up to construct those plants, and put a low limit on the rate of future production using that equipment.

Antice
2009-May-26, 07:52 AM
Beaming power back to earth makes no sense what so ever actually. try to actually considder the cost of those solar sat's and the recieving equipement. the ground stations has to be huge to be able to safely recieve enough power to power even a midsized city.
as far as better use for investement you are better off employing solar panels here on earth. start by covering all the roofs to reduce base loads and you are finally getting someplace. solart panels that do not have to cope with the space environment can be made very cheap. they do not have to be mass efficient either, as they can easily do double duty as roof tiling etc.
for hot places in the world where the primary load is AC's then the solar power is a great way to reduce dependancy on grid delivered power. however. adding the step of beaming it from space is just making it cost more. not less

cjameshuff
2009-May-26, 09:42 AM
Beaming power back to earth makes no sense what so ever actually. try to actually considder the cost of those solar sat's and the recieving equipement. the ground stations has to be huge to be able to safely recieve enough power to power even a midsized city.

Rectenna receivers are far more efficient than photovoltaics, almost all of what reaches the ground being converted into usable power, so the area requirements are much lower than those for solar power. And wire mesh rectennas allow water, wind, and sunlight through...stick them over crops and they'd just add some protection from severe weather.



as far as better use for investement you are better off employing solar panels here on earth. start by covering all the roofs to reduce base loads and you are finally getting someplace. solart panels that do not have to cope with the space environment can be made very cheap. they do not have to be mass efficient either, as they can easily do double duty as roof tiling etc.
for hot places in the world where the primary load is AC's then the solar power is a great way to reduce dependancy on grid delivered power. however. adding the step of beaming it from space is just making it cost more. not less

Manufacture of photovoltaics requires a lot of energy and large amounts of some extremely hazardous and rather exotic chemicals to produce the needed ultra-pure silicon and precisely dope it...having to deal with weather, bird crap, and all the other abuse inflicted on roofs on top of that will never make them "very cheap".

In any case, as my posts have very clearly indicated, I'm thinking specifically of solar thermal power plants built using local resources, not photovoltaic cells shipped from Earth as you clearly assume, and SPSs as a way to get more return on an investment, not as the primary goal. Invest in solar panel roofs and you get solar panel roofs that you have to collect, recycle, and replace in a matter of years, and millions of cheaply made inverters each trying to push a trickle of power onto the grid and likely themselves requiring several replacements in the lifetime of the panels. Invest in establishing some basic space-based industry and you get affordable solar power satellites almost as a side benefit.

Antice
2009-May-26, 10:17 AM
Asuming that anything space related can be considdered basic is a falacy. it's not. The amount of mass and energy needed to even start making these things from off world resources is staggering. it would take hundreds of not thousands of years to make it pay off when compared to other options.

Antice
2009-May-26, 11:09 AM
re durability of solar roofs. there are more ways than photovoltaics available on earth also. Solar cells are covered in clear plastic, no harder to fix than any other roof. They are stil way cheaper than your proposed orbital power stations for the simple fact that those power stations are not feasible without major space industry.
Simpler/cheaper more environment friendly solar cells for earth use are under developement as well. while solar power will never be a main baseload contributor on earth it has the potential to act very well as a peak load diminisher for sunny parts of the world. for the cold parts. well. those are too far north/south to benefit from neither earth based nor orbital solar power annyhow.

Baseload is most economically and environmentaly soundly suplied trough fission near term and fusion when/if they get that working right in the long term. these are the technologies that should be used as a reference on viable cost vs benefit analysis.

Ara Pacis
2009-May-26, 02:03 PM
Asuming that anything space related can be considdered basic is a falacy. it's not. The amount of mass and energy needed to even start making these things from off world resources is staggering. it would take hundreds of not thousands of years to make it pay off when compared to other options.

Any reason to think that's not mere hyperbole?

BTW, nuclear will need to be used in space at locations short of sunlight either far from the sun, such as the asteroid belt, or close but shaded, such as a mobile base on the dark side of Mercury.

aquitaine
2009-May-26, 03:48 PM
Nuclear power requires nuclear fuel, which would need to be imported from Earth,

Yes but that amount will last for many many months. The nice thing about nuclear is the Uranium needed to power it is actually a surprisingly small amount and it can be stockpiled easily.

Yes solar can be directly harvested, but the actual power density provided is rather low, so it takes a large area to get the same power from one nuke plant, even a small one.

aquitaine
2009-May-26, 04:10 PM
Nuclear power requires nuclear fuel, which would need to be imported from Earth,

Yes but that amount will last for many many months. The nice thing about nuclear is the Uranium needed to power it is actually a surprisingly small amount and it can be stockpiled easily.

Yes solar can be directly harvested, but the actual power density provided is rather low, so it takes a large area to get the same power from one nuke plant, even a small one.

Antice
2009-May-26, 07:16 PM
large area is only one thing. there is a structural limit to how large you can make them without a heavy bracing structure to help them maintain their shape.

Orbital mechanics is nasty for overly large structures. especially big flat ones like that of our concept SPS.
Let's imagine our orbit as a circle around the earth. now at each corner of the circle you draw in your SPS. it has to face towards a point far outside the circle. in the centre of this circle you place earth. we start our orbit in earth's shadow. the satellite now has it's collectors aligned with the circle and all parts are orbiting at the same speed around the orbit. move one fourth around and look at your orientation now. it's changed. it's now 90 degrees offset from the direction of movement. as per orbital mechanics the part in a lower orbit will tend to pull ahead of the part in the higher orbit. this causes the satellite to tend towards spinning.
Unchecked this will cause your power satellite to start a reverse barrel roll around. that ofc isn't good since you want it to stay aligned with the sun. the other option is to have it aligned with earth. give it a spin rate that let's it roll around with the same side facing down at all times. tidal forces from the earth will help you keep it stable. however. now you are faced with the fact that your panels aren't facing the sun at all times any more. they are actually only facing the right way only once per orbit. this just wont do. so how do we counter it? well one well known way is to have more mass.
Like on the ISS. a big heavy truss that remains aligned with the earth, taking advantage of being tidally locked into keeping the same side down. the panels would have to be able to rotate freely around this truss in 2 dimensions. just like the ones on the ISS does. this is heavy. the more solar collecting you do the bigger and heavier the truss and accompanied powered rotary joints you need.
All of these issues can be solved. but each solution adds structural mass. lots of mass. that mass has to come from some place. and before you say the moon or neo or any other fav. stop and think about costs again. it costs billions just to send a a couple of expeditions to the moon. you can expect even a small research base to cost on the order of 20 or 30 billions easy. (including the cost to develop everything)
I think we can safely dismiss lunar or Neo asteroid manufacture of SPS for quite a while yet. for that kind of money we could build several TW scale nuclear power plants to feed the worlds energy needs. we have the fissile material needed to keep going for a long while still. once the uranium is used up we can go over to using thorium (http://en.wikipedia.org/wiki/Thorium#Thorium_as_a_nuclear_fuel). Norway alone has enough of that for 10 000 years worth of the worlds energy needs. it's currently just sitting up in them mountains doing nothing at all.

I'm not saying that the concept might not be viable one day in the far future. but as a solution for today's energy needs it's not.
for the far future. well... build them closer to the sun. and use that power to make antimatter for fuelling interstellar spacecraft. by then we will have mastered fusion most likely. so powering the planet wont be an issue any more.

cjameshuff
2009-May-26, 08:29 PM
BTW, nuclear will need to be used in space at locations short of sunlight either far from the sun, such as the asteroid belt, or close but shaded, such as a mobile base on the dark side of Mercury.

Don't disagree for the most part, just forgot to mention them...for Mars, whatever asteroids prove useful, and especially for gas giant moons. A polar Mercury base would be perfectly able to use solar power, though. (Mercury doesn't have a permanently dark side.)


aquitaine: you're still talking about shipping fuel up every few years at least for every reactor in service, and nuclear reactors are far more complex, they would have to be built on Earth and shipped up. Yes, it takes a lot of collector area to equal the output of a nuclear plant, and that matters a great deal on Earth and on mobile spacecraft, but it matters very little in orbit when materials no longer have to be imported from Earth. Solar thermal power could be expanded far more with much smaller and less costly shipments...things like replacement tooling and high-tech components.



large area is only one thing. there is a structural limit to how large you can make them without a heavy bracing structure to help them maintain their shape.

Orbital mechanics is nasty for overly large structures. especially big flat ones like that of our concept SPS.

Do you have any idea what those limits actually are?

The ISS is once again a particularly bad example. Aside from those components being constructed on Earth's surface and exposed to the stresses of launch, the ISS is in low Earth orbit, and subject to much higher tidal forces (nearly 300 times as strong as those experienced in geosynchronous orbit, about 200000 times as strong as those at the Earth-Luna L4 and L5 points, and about 60000 times as strong as that at Earth-Luna L1) as well as atmospheric drag that requires periodic boosts back into higher orbits. Higher orbits experience far lesser tidal effects and do not require those orbit maintenance burns, they could hold station with ion engines, and may not even require that. They may even be able to use solar light pressure to compensate for perturbations to their orientation.

And you're still talking about the required space industry as a downside. Once again, I am not suggesting that orbital industry be established, used to construct SPSs, and thrown away. The power satellites represent one source of demand that becomes feasible once that industry is in place. Establishing that industry is going to require large amounts of power, the equipment to produce the materials and machinery to produce that power is going to be one of the most expensive parts of setting things up. The more power production capacity you build and use using that equipment, the more it makes sense.

Antice
2009-May-26, 10:41 PM
And you are back to the chicken and egg. this circle is endless. fact is. there is nothing in space except space. and we are not short of that on earth. Yet at any rate.
If you want your sps's out at any of the lagrangian spots it makes no sense to try to beam any of that power back. the distance is so large as to cause massive inefficiencies... Geostationary might work. but the forces you have to contend with are acting on a humongous area. it's not that the forces are large. but even for a modest 100MW.. let's do the maths.
Let's look at the best in solar power today. ISS again. the ISS has 8 solar wings each with an area off 420m2. that is 8x420= 3360m2. it generates a total of 262KW. when new that is. that gives an area to power ratio off 3360/262=12,8m2/KW

however. we need something on the order of 100MW to drive any significant ore processing like modest aluminium refining.
that is 100 000KW.... makes you need a whooping 1 280 000m2 of the best photovoltaic's around. or in other words. it's a square that is 1131 meters to a side..... at those scales tidal forces do become an issue. even at geostationary. the structure needs to be quite stiff in order to avoid any buckling due to orbital differences. the area needed is quite comparable to solar thermal. since you can at most get around 50% efficiency out of such a system as well. preventing the power plant from melting will cost power. and in a vacuum you cant just dump heat into something else like on earth.
If you think maintaining solar roof tiles on earth is a big undertaking. (one that the individual home owners would be doing by themselves anyhow. each owns his own roof after all). try thinking of trying to maintain a town/village sized area in space instad.

Trakar
2009-May-26, 11:39 PM
And you are back to the chicken and egg. this circle is endless. fact is. there is nothing in space except space. and we are not short of that on earth. Yet at any rate.
If you want your sps's out at any of the lagrangian spots it makes no sense to try to beam any of that power back. the distance is so large as to cause massive inefficiencies... Geostationary might work. but the forces you have to contend with are acting on a humongous area. it's not that the forces are large. but even for a modest 100MW.. let's do the maths.
Let's look at the best in solar power today. ISS again. the ISS has 8 solar wings each with an area off 420m2. that is 8x420= 3360m2. it generates a total of 262KW. when new that is. that gives an area to power ratio off 3360/262=12,8m2/KW

however. we need something on the order of 100MW to drive any significant ore processing like modest aluminium refining.
that is 100 000KW.... makes you need a whooping 1 280 000m2 of the best photovoltaic's around. or in other words. it's a square that is 1131 meters to a side..... at those scales tidal forces do become an issue. even at geostationary. the structure needs to be quite stiff in order to avoid any buckling due to orbital differences. the area needed is quite comparable to solar thermal. since you can at most get around 50% efficiency out of such a system as well. preventing the power plant from melting will cost power. and in a vacuum you cant just dump heat into something else like on earth.
If you think maintaining solar roof tiles on earth is a big undertaking. (one that the individual home owners would be doing by themselves anyhow. each owns his own roof after all). try thinking of trying to maintain a town/village sized area in space instad.

There seem to be a lot of false, or at the least, unsupported statements in the above:

ISS panels exemplify state of the art and best on the horizon PVC technology, much less the preferrable technology for an SPS system.

that 1Km^2 is outrageous (most serious SPS system plans are calculated based upon much large collection areas and figure multiple gigawatt power generation)

that a square km structure would suffer tidal stress such that the system is not viable in Geostationary orbit.

that the backside shadow of solar thermal collection system would be incapable of blackbody IR dumps of excess of waste heat.

that there is any comparison between the maintenance and upkeep of solar power roof tiles exposed to the Earth's surface weather and orbital SPS panels

probably more, but these are enough for now.

cjameshuff
2009-May-27, 12:05 AM
fact is. there is nothing in space except space.

Trivially wrong. There's mineral and energy resources vastly exceeding what is accessible on Earth, and which can be accessed without causing environmental damage.



If you want your sps's out at any of the lagrangian spots it makes no sense to try to beam any of that power back. the distance is so large as to cause massive inefficiencies...

The L1 example was for supplying power to the moon. The L4 and L5 locations would be more suitable for supplying power to in-orbit industry at those points. However, they would only require transmission arrays 9 times as large in linear dimensions to achieve the same spot size on the ground on Earth. If tidal forces were truly an issue at GSO (they aren't), it would be feasible to put them at the L4 and L5 points instead, the main problem being the loss of synchrony with Earth's rotation.



Geostationary might work. but the forces you have to contend with are acting on a humongous area. it's not that the forces are large. but even for a modest 100MW.. let's do the maths.

Yes, lets do them!



Let's look at the best in solar power today. ISS again. the ISS has 8 solar wings each with an area off 420m2. that is 8x420= 3360m2. it generates a total of 262KW. when new that is. that gives an area to power ratio off 3360/262=12,8m2/KW

The ISS is, once again, a terrible example. It spends much of its time in Earth's shadow, and uses photovoltaic conversion much less efficient than the 50% efficiency you gave for solar thermal. Overall, given your figures, the ISS panels have an effective efficiency of 6%.



that is 100 000KW.... makes you need a whooping 1 280 000m2 of the best photovoltaic's around. or in other words. it's a square that is 1131 meters to a side..... at those scales tidal forces do become an issue. even at geostationary. the structure needs to be quite stiff in order to avoid any buckling due to orbital differences. the area needed is quite comparable to solar thermal. since you can at most get around 50% efficiency out of such a system as well. preventing the power plant from melting will cost power. and in a vacuum you cant just dump heat into something else like on earth.

Given the nearly factor of 10 difference in efficiency between your ISS example and the hypothetical 50% efficiency thermal plant, the area is *not* comparable. At 50% conversion efficiency (which I don't expect and which is not required for the earlier plants to be useful), given 1366 W/m^2 of sunlight, a 100 MW plant would need a 270 m square of collectors, or a circle 152 m in radius...call it 200 m radius to give some leeway for incomplete coverage of the area.

At 42164 km, the difference in gravitational acceleration of free bodies separated by 400 meters would be 0.004 mm/s^2 at most. Assuming structural mass of 10 kg/m (aluminum mirrors nearly 4 mm thick, or more realistic mirrors and a reasonable portion of support structure), the tension at the center of the structure is about 8.5 millinewtons. You would need to apply a restoring force of 43 micronewtons to the outermost elements to keep them in position. I don't feel the need to go into more detail...your claims about tidal forces being an insurmountable obstacle are clearly incorrect.

And no, keeping the plant from melting does not cost power. Power is produced from the temperature difference between the focus of the reflectors and the radiators, reducing that temperature difference in the process. To keep it from melting, you just design it so the hot side doesn't exceed the melting point of its materials.

Ara Pacis
2009-May-27, 01:47 AM
...and accompanied powered rotary joints you need.

Or you could use light cables and only a couple powered rotary joints and operate it like a window blind. To get or maintain a different rotation for each mirror (if you're using mirrors instead of parallel PV panels), each mirror could have a different length cam.

Antice
2009-May-27, 05:59 AM
re unsurmontable tidal forces. I never claimed they were insurmontable. but your claim that they are irrelevant is simply not true when considdering the scale of even a modest earth launched system of a measly 100MW. the forces acting on an object of such a size are an issue that will be a major design driver.
What i do claim is that SPS is not viable for the time being. and i am not talking just short term either. they will remain unviable until such time that major industrial capacity exists in space already. and their first use might very well not be to power earth at all. but rather AM factories in closer orbit's to the sun.
While solar power is great for powering stuff at smaller scales it's not a good powersource for multiple GW of energy needed for a real industrial complex in space.
bootstrapping such industry is very launch cost intensive. since initially you have to suply everything from earth. that means that the first 100MW powersource for the first aluminium processing plant has to be launched from earth. considdering how massive even the best on offer ends up being when it comes to solar power.
Nuclear certainly makes more sense.
Any orbital power scheeme has to take into account that nuclear is a mature technology that is already capable of delivering massive amounts of power quite cheaply. both in environmental terms and money terms. despite being handicapped by unwieldy laws and regulations.
Solar power satelites do have nimby issues too you know. nobody wants to live near those rectennas no matter how safe you claim them to be.

cjameshuff
2009-May-27, 08:52 AM
Or you could use light cables and only a couple powered rotary joints and operate it like a window blind. To get or maintain a different rotation for each mirror (if you're using mirrors instead of parallel PV panels), each mirror could have a different length cam.

Light cables would be far heavier for the power they carry. Even light pipes would be lossy and heavier than necessary. Much simpler to just rotate the whole collector mirror/power plant unit once a year, since the worries about tidal forces mangling the structure are spurious. Could potentially do the conversion to microwaves there too, and use waveguides to reach the Earth-synchronous transmission antennas.



re unsurmontable tidal forces. I never claimed they were insurmontable. but your claim that they are irrelevant is simply not true when considdering the scale of even a modest earth launched system of a measly 100MW. the forces acting on an object of such a size are an issue that will be a major design driver.

I didn't claim they were irrelevant. They will need to be taken into account, yes, the mirror segments will likely have to adjust their aim as the structure flexes slightly. They are just not any great difficulty. You do not need a monstrously heavy backbone, as you claimed.

A 168 kg, 10 cm OD, 9.8 cm ID circular aluminum tube 200 m long, held rigid at one end and with 43 uN applied perpendicularly to the far end...a situation far worse than would actually be encountered...will deflect by about 2-3 cm. Does this make it clearer what I mean when I call the tidal forces "small"? A structure fragile enough to be adversely affected would be seriously difficult to construct in the first place. The tidal forces are within an order of magnitude of the forces from radiation pressure. Those will have to be taken into account too, but the SPS is in no danger of being blown to shreds by sunlight, either.



While solar power is great for powering stuff at smaller scales it's not a good powersource for multiple GW of energy needed for a real industrial complex in space.

Yes it is. See previous posts.



bootstrapping such industry is very launch cost intensive. since initially you have to suply everything from earth. that means that the first 100MW powersource for the first aluminium processing plant has to be launched from earth. considdering how massive even the best on offer ends up being when it comes to solar power.

Aside from your questionable assumption that the power plant used to bootstrap production would be big enough for full-scale aluminum production...you're essentially saying that solar thermal is too expensive because of the nuclear power plant required to start things off. This is not particularly compatible with your argument that shipping lots of large nuclear power plants into orbit is a better alternative.



Nuclear certainly makes more sense.

For some things. For the initial bootstrap plant, which could be a little sub-megawatt thing. For spacecraft that must move. For stationary facilities, given how cheap arrays of concentrator mirrors fabricated from local materials could be in comparison to complex high-power orbital reactors and fuel shipped from Earth, nuclear makes considerably less sense.

Your 100 MW starter plant is typical of your arguments...wildly inflated requirements. Say an early generation solar-thermal plant takes 150 kg of aluminum per m^2 of collector area and associated power plant, and operates at 30% efficiency. At 50 J/kg, which the most modern aluminum smelters can outperform, a 1 MW starter plant could produce the materials for 1 MW of solar thermal plant in 210 days, assuming all power for that duration was devoted to aluminum refining.

Every post you make consists of vague moaning about it being too difficult or too expensive, with little in the way of substantial arguments. You consistently ignore any benefits, exaggerate the difficulties, and pick the worst possible comparisons to support your point. Do you have any real objections, or are you going to ignore the points brought up and respond with "it's too hard" again?

aquitaine
2009-May-27, 02:03 PM
For some things. For the initial bootstrap plant, which could be a little sub-megawatt thing. For spacecraft that must move. For stationary facilities, given how cheap arrays of concentrator mirrors fabricated from local materials could be in comparison to complex high-power orbital reactors and fuel shipped from Earth, nuclear makes considerably less sense.

Each one of those large panels on the ISS can only generate 32 KW, but they measure 107 by 38 FEET. Now, for comparison a Hyperion Power Module is 1.5 meters wide and 2 meters tall, about the size of your average home jacuzzi and it is capable of making 25 MW of electricity, granted it is heavy clocking in at 20 tones, but it is a far more efficient usage of space. To get the same amount of power with a solar array you would need something 781 times the size of one of the ISS panels. Inefficiency at its finest.

cjameshuff
2009-May-27, 07:56 PM
Each one of those large panels on the ISS can only generate 32 KW, but they measure 107 by 38 FEET.

It's already been pointed out that the ISS power figures are worthless for this discussion. They are photovoltaics, they do not continuously face the sun, they in fact spend significant time in complete shadow, and they are built to be launched on and assembled by a Shuttle and attached to a space station that must periodically boost itself into a higher orbit.



Now, for comparison a Hyperion Power Module is 1.5 meters wide and 2 meters tall, about the size of your average home jacuzzi and it is capable of making 25 MW of electricity, granted it is heavy clocking in at 20 tones, but it is a far more efficient usage of space. To get the same amount of power with a solar array you would need something 781 times the size of one of the ISS panels. Inefficiency at its finest.

Inefficient use of what? If you haven't noticed, we're not short on space in high orbit, or on the moon for that matter. It's not inefficient to use lots of space. It *is* inefficient to import reactors from Earth when you can construct arbitrary amounts of solar power production from more local materials.

In any case, you do not need collector area 781 times that of the ISS panels. The Hyperion module quotes 70 MW thermal, 25 MW electrical with a typical Brayton cycle turbine (turbine not included). That's a conversion efficiency of 36%...not particularly high for a terrestrial plant, perhaps due to a relatively low outlet temperature on the reactor, but 6 times the effective ISS panel efficiency. For a 36% efficient solar thermal plant in a high orbit, you need 140 times the area, 12 times the linear dimensions.

Even if you did need collectors as large as you claimed, your objection is just "they're big!"...you haven't shown that they are inherently unworkable. Once you can mass produce 6% efficiency solar cells, it may even be a practical approach.

For a 320 K radiator temperature (a reasonable guess at what the Hyperion module requires, being a terrestrial power plant) with an emissivity of 0.96, you'd also need 210 times the area of the ISS solar wings in radiators along with the Hyperion module. You'll also need a sun shield for those radiators, in the solar thermal plant the collector mirrors serve this purpose. The only thing you've done is replace the mirrors with sun shields and an expensive reactor.

Mobile applications are more concerned with compactness and energy density than with efficiency. They can use smaller radiators. However, whether using solar thermal or nuclear, given industry that needs the power and can construct radiators, there's no major reason to use such small and wasteful radiators for stationary applications.

aquitaine
2009-May-28, 04:44 AM
Inefficient use of what? If you haven't noticed, we're not short on space in high orbit, or on the moon for that matter. It's not inefficient to use lots of space. It *is* inefficient to import reactors from Earth when you can construct arbitrary amounts of solar power production from more local materials.

It's a waste of resources, it costs money to carry those up there and because of their size you would need to make multiple trips because there is only so much that can be taken on each trip. Uranium is the most energy dense fuel source we've ever discovered, 1 kg is equal to 1000 tones of coal, so the amount needed for a small reactor is not much.


For a 320 K radiator temperature (a reasonable guess at what the Hyperion module requires, being a terrestrial power plant) with an emissivity of 0.96, you'd also need 210 times the area of the ISS solar wings in radiators along with the Hyperion module. You'll also need a sun shield for those radiators, in the solar thermal plant the collector mirrors serve this purpose. The only thing you've done is replace the mirrors with sun shields and an expensive reactor.

I dont recall heat exchangers even on large reactors being anywhere near that size.


EDIT: I found out the P6 array weighs about 16 tons total, with 4 solar panels that makes for 4 tons each. Btw, why would the coolant need to be shielded from the sun? If it's absolutly needed, then why not keep it in the station's shadow? Space is a cold place, and a good place to dump the reactor's waste heat.

Trakar
2009-May-28, 07:07 PM
It's a waste of resources, it costs money to carry those up there and because of their size you would need to make multiple trips because there is only so much that can be taken on each trip.


Size does not equal mass, that is the issue of in orbit construction versus boosting large component pieces. The component pieces take up volume regardless of mass. The more basic materials are more compact and thus take up less volume in a booster. Final manufacture and construction in orbit, means fewer launches to yeild the same final product.

aquitaine
2009-May-29, 12:51 AM
That's what I meant. :)

cjameshuff
2009-May-29, 02:17 AM
It's a waste of resources, it costs money to carry those up there and because of their size you would need to make multiple trips because there is only so much that can be taken on each trip.

Yes, it costs money to carry stuff up from Earth...this is why I'm advocating a power source that can be built from local materials for those applications that don't require the compactness of nuclear power. You can build solar thermal power plants relatively easily from lunar (or asteroid) materials, rather than shipping up heavy reactors and periodic shipments of replacement fuel from Earth.

Early on, solar plant construction would still need to import many parts from Earth, but as orbital industry develops the reliance on those parts goes away, eventually allowing plants to be constructed without importing any parts from Earth at all. For nuclear power, the reliance on Earth for reactors and fuel only increases as more power is needed. This limits how far orbital industry can grow, and the cost of all those reactors and fuel resupply missions adds up.



Uranium is the most energy dense fuel source we've ever discovered, 1 kg is equal to 1000 tones of coal, so the amount needed for a small reactor is not much.

So the lesson here is that nuclear power's a better option for an orbital power source than coal. Fine. No disagreement there.



I dont recall heat exchangers even on large reactors being anywhere near that size.

Why did you ignore the paragraph immediately following the text you quoted? For that matter, you apparently didn't pay much attention to the one you quoted. Small, hot radiators leading to low conversion efficiency are an acceptable tradeoff in applications where a compact and high density source of power is required. When it's not required, and when you're not limited to radiators you can ship up from Earth, they just waste power.



EDIT: I found out the P6 array weighs about 16 tons total, with 4 solar panels that makes for 4 tons each.

I've pointed out numerous times several reasons why the ISS solar arrays are not a useful comparison. Once again, it does not matter how big they are, how heavy they are, how much they cost, or how much power they produce. They don't even remotely resemble the system you're arguing against.



Btw, why would the coolant need to be shielded from the sun? If it's absolutly needed, then why not keep it in the station's shadow? Space is a cold place, and a good place to dump the reactor's waste heat.

Space is not hot or cold. Space is a vacuum, with a 2.7 K background over most of the sky and, in the vicinity of Earth orbit, 1366 W/m^2 with a black body temperature of 5778 K coming from a sphere covering a portion of the sky about half a degree across, plus Earth and the moon, at a much cooler temperature over a typically larger portion of the sky (sometimes smaller for the moon, depending on the orbit the station's in). The only way to lose heat is by radiation, and the radiator areas required to radiate large amounts of waste heat at low temperature are quite large.

Sunlight on the radiators warms them and decreases the efficiency of converting thermal power to electrical power. You can turn them edge on to the sun, but putting them in permanent shade would be even more effective. An array of concentrator mirrors can easily double as a sun shield. A nuclear reactor, as you have repeatedly pointed out, is relatively small, so it is not very practical to put the radiators in its shadow.

Antice
2009-May-30, 07:45 AM
Why even bother putting this in geo? it's far less of a hazzle to make all the parts you want on the moon then launch them from there for final assembly. you are quite obviously dependant on off world resources. and geo happen to have absolutely none except vacuum. there is a reason most refineries are relatively close to their source of raw materials. aluminium is the exception here not the rule due to it's high energy demand. makes more sense to have it close to the power. but hey. the moon can have lots and lots of that too. use the moon rock as a heat sink for your nuclear plant. doing the melting and refinery in 0g is like passing the stream to get water. it's just not needed when you can do it where the raw materials are present already. Solar power satellites don't have to compete with orbital nuclear. they have to compete with ground based nuclear. on the ground the entire plant is sitting in one giant heat sink already. and aprox 70% of it's surface is covered in ready to use coolant as well.
0g refineries would work well if they are movable. using asteroid materials. since once a single asteroid is played out it's more efficient to move it to the next one than to waste the plant.

Ara Pacis
2009-Jun-13, 03:54 PM
Light cables would be far heavier for the power they carry. Even light pipes would be lossy and heavier than necessary. Much simpler to just rotate the whole collector mirror/power plant unit once a year, since the worries about tidal forces mangling the structure are spurious. Could potentially do the conversion to microwaves there too, and use waveguides to reach the Earth-synchronous transmission antennas.

Um, I was referring to the movement of louver-like panels with cables made of a lightweight(lightmass) material, not the use of light-transmitting pipes or fiber-optics.

rommel543
2009-Jun-29, 11:02 PM
Ok digging up this thread because I just read this article...
Uranium Found on the Moon (http://www.space.com/scienceastronomy/090629-uranium-moon.html)


Furthermore, since uranium supplies on Earth are scarce, mining uranium on the moon to satisfy our energy needs at home could prove lucrative.

cjameshuff
2009-Jun-30, 01:40 AM
Ok digging up this thread because I just read this article...
Uranium Found on the Moon (http://www.space.com/scienceastronomy/090629-uranium-moon.html)

Lunar uranium seems a valuable resource for lunar bases and orbital operations, if it's concentrated enough (IIRC, uranium ores are hydrothermal minerals, concentrated by hot liquid water, a phenomenon likely not widespread on the moon). There's no imminent shortage of it on Earth, though...it's relatively scarce, but there's so much depleted uranium around that we use it for bullets and ballast...and it can be burned in breeder reactors. There's also a lot more mineable thorium than uranium.

roverich
2009-Jun-30, 01:53 AM
But would it be cost effective to spend the millions to go there , get the stuff and bring it back ...In this economy ..

filrabat
2009-Jun-30, 02:36 AM
I love that idea, Trantor.

Problem is, we have to have the probe, power source, and navigational finesse to guide a "Dinosaur Killer" into orbit under our geosynchronous orbit YET still keep it from hitting the earth! I suppose we can orbit it around the moon and send some robots to do the dirty work. Still, there are going to be some things that will require a human to do.

Certainly building even a "small" permanently habitable space habitat (NOT a "mere" "space station") with a half-way sustainable environment will require "grinding down" an asteroid and reassembling it into a station - something best done directly by robots.

Jason Chapman
2009-Jun-30, 03:33 AM
Basically, its IKEA in orbit.

Now there's a scary thought.

Antice
2009-Jun-30, 05:58 AM
Now there's a scary thought.

let me be the first to remind you that IKEA style assembly is THE most common way to construct large buildings and ships.
what you assemble in the drydock when building a supertanker is large prefab hull structures complete with all fixtures and plumbing.

Modularity for space construction are not limmited to fully contained modules. there is nothing wrong with welding 2 or more parts together in space. Once the techniques for doing so have matured to the point where it can be done with a high degree of confidence.

Ara Pacis
2009-Jun-30, 06:40 AM
But would it be cost effective to spend the millions to go there , get the stuff and bring it back ...In this economy ..

We need jobs. A huge space infrastructure and mining program would create jobs. Sounds like it might work in this economy.

Ara Pacis
2009-Jun-30, 06:53 AM
let me be the first to remind you that IKEA style assembly is THE most common way to construct large buildings and ships.
what you assemble in the drydock when building a supertanker is large prefab hull structures complete with all fixtures and plumbing.

Modularity for space construction are not limmited to fully contained modules. there is nothing wrong with welding 2 or more parts together in space. Once the techniques for doing so have matured to the point where it can be done with a high degree of confidence.

I agree with the concept of "Grand Blocks (http://tigris.marin.ntnu.no/byggeteknikk/start/LoadBearingStructure/ShipBuilding/C-BlockFab/GrandBlock/)". It's what I've been planning on using for my stories and letters to senators.

As for "Ikea-style", I was thinking it referred less to preformed modules and more about the "flat-pack" shipping format. Many real space habitat designs may actually use that basic principle. Exterior bulkheads may be erected for structural support, especially if necessary to support regolith for radiation shielding, then an inflatable inner lining will provide the air seal either along the entire perimeter or at the edges and corners as a hinge and seal. Inner partitions will probably also be flat-pack modular designs for cabinets and furniture.

Antice
2009-Jun-30, 08:45 AM
Flatpacks aren mainly used for homes and office buildings on earth. Flatpacks might not be a useful way to do it in space. especially since you need a whole nother level of integrity when talking about boats and space vehicles.
Some parts can be flatpacks tho. like strap on shielding plates and such. those do not have be airtight.

Ara Pacis
2009-Jul-01, 05:03 PM
Flatpacks aren mainly used for homes and office buildings on earth. Flatpacks might not be a useful way to do it in space. especially since you need a whole nother level of integrity when talking about boats and space vehicles.
Some parts can be flatpacks tho. like strap on shielding plates and such. those do not have be airtight.

I've seen footage of an inflatable habitat with flatpack floors for use on a planetary surface which was produced by NASA, IIRC.

Antice
2009-Jul-01, 05:59 PM
I'd not define an inflatable as a IKEA flat pack. there is that thing with "some assembly required" message that is always printed on those packages.
Inflatables are a great way to make a big module launch able within a limited shroud.

Ara Pacis
2009-Jul-01, 06:18 PM
I'd not define an inflatable as a IKEA flat pack. there is that thing with "some assembly required" message that is always printed on those packages.
Inflatables are a great way to make a big module launch able within a limited shroud.

In the example I mentioned, the exterior was an inflatable shell, the internal structures, like the floor and panels, were hinged and essentially, flat-packed. I consider it to be the same thing as I've had flat-pack furniture that was essentially hinged, with only a little bit of screwing in fasteners for the bracing. As for inflatable, I wouldn't call it flat-pack, but they work well together.

NEOWatcher
2009-Jul-02, 02:27 PM
...I consider it to be the same thing as I've had flat-pack furniture that was essentially hinged, with only a little bit of screwing in fasteners for the bracing...
Interesting... I've never seen that kind (hinges, that is)


...As for inflatable, I wouldn't call it flat-pack, but they work well together.
I think maybe a good analogy is a pop-up camper (http://www.campingearth.com/popups/).

Ara Pacis
2009-Jul-03, 04:07 AM
Interesting... I've never seen that kind (hinges, that is)Well, not with a piano or door type of hunge, but with a creased and flexible backing. It was a bookcase and the backing was already attached and folded out with the MDF side panels.



I think maybe a good analogy is a pop-up camper (http://www.campingearth.com/popups/).I like that idea too, although it's a little different than what I was referring to. The one I saw was softsides with an inflatable cylinder restrained by externally placed straps. The folding hard structure was for the internal deck and partitions. I'm not sure if it is the same or similar to this design: http://www.nasa.gov/exploration/home/inflatable-lunar-hab.html

NEOWatcher
2009-Jul-06, 12:22 PM
I like that idea too, although it's a little different than what I was referring to. The one I saw...
Yes; they will be different. I was just showing it as an analogy because the concept is the same. The important mechanical structures are rigid and foldable while the space containment is not.

I'm sure a camper would be totally different if they were made inflatable. ;)

Ara Pacis
2009-Jul-08, 07:40 AM
And we might go a step further and use a one-time-setup foldable or inflatable system, where the expanded portions are somehow permanently locked into place. This could be as simple as nuts and bolts (and other mechanical fasteners), welds, or adhesives, but it could also include two-part epoxies used to fill and solidify parts of an inflatable envelope.

I think that a Heavy Lift Launch Vehicle, like Ares V, with a large shroud size could be used to send up large but fairly lightweight empty sections for larger structures. These sections might be hexagonal, and be fitted together to form different styles of station or large interplanetary craft. I assume I'm not the first person to think of this, but it seems fairly straightforward.

RGClark
2009-Jul-16, 06:20 AM
Ok digging up this thread because I just read this article...
Uranium Found on the Moon (http://www.space.com/scienceastronomy/090629-uranium-moon.html)

Might make possible manned missions to the outer planets using nuclear reactors without the concern of launching large amounts of radiative materials from the Earth.


Bob Clark