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Drbuzz0
2007-Oct-27, 04:22 PM
China is just getting their feet wet in manned space flight. They made their first manned capsul flight using a soyuz-like craft that had limited endurance. They have already stated that they want to fly a manned moon mission in the next couple decades and they just sent their first probe to the moon.

Japan, a country which has begun a serious scientific space probe program on their own has focused much of their energy on sending lunar orbiters to survey the moon both for pure research and for a possible manned moon mission. They have not yet flown a manned mission of their own and they lack any heavy lift platforms which would be able to support manned missions at this time.

India, a country who's recent technological expansion has established a thriving scientific community - but has not exactly helped eliminate poverty amongst the nearly one billion citizens, many of whom live bellow the poverty line - has just begun to develop it's own satellite launch capabilities and has a rather limited space flight record. They have stated that they are planning a lunar exploration program.

The ESA and Russia have also stated that they have interest in their own lunar programs in the future. And of course, the US has already begun a program to return manned spacecraft to the moon.


For countries which have only just begun to reach into space, the moon seems like the ultimate in high-priced, low-return missions. Going to the moon may be worthwhile from a purely scientific standpoint, but as far as resources, it doesn't really have any which are worth bringing back. The only one mentioned as possible is Helium-3. But that is only worthwhile if fusion reactors for power come into being. That may never happen, and even if it does, the only advantage of helium-3 is that it would produce less irridiation of the reactor material. Deuterium works nearly as well and is much more easily avaliable. And helium-3 can be manufactured by collecting it from the decay of tritium, which can be made by neutron bombardment of lithium.

For such countries, there is a long way to go to simply establish a reliable manned launch system. Or for that matter, to even establish a reliable and highly capable satellite launch capability. Going to the moon might not be impossible, but it would necessarily be highly expensive and focus a great deal of resources on the moon to the detriment of other system.


There is a lot more opportunity in space that does not involve the moon. Unmanned LEO payloads can be used for equally important scientific missions, such as various astronomical sensors and detectors. Commercial satellite launches of both LEO and GEO communications satellites are an important capability. And space offers many abilities for military and government projects.

Manned space flights to a space station are also highly useful for science and other purposes. Although necessarily expensive, it is not as expensive as a lunar program and can be done in stages that do not require nearly as large a launch platform as going to the moon.

There are a variety of things that a country could plan for space which have high potential returns. Space stations, unmanned pure-science missions, governmnet and military missions, commercial launch capabilities, satellite servicing missions - manned and unmanned, developing more cost-effective or reusable launch components. All of these have potentially large benifits. The moon seems to be something which offers the same or less at a much higher price.

All I can think is that it is nationalism or an attempt to prove that a country "Can do it" but that's... a lot of money to prove a point. Especially for a country like Japan, which doesn't really have much to prove about it's technology.

AtomicDog
2007-Oct-27, 05:47 PM
This anti-lunar pattern in your threads - you must not like the moon very much.

Tucson_Tim
2007-Oct-27, 05:51 PM
I think it's great - the more the merrier. But it would be nice if there was some cooperation, like with the ISS, to allow more to be accomplished with the money spent. Same with the planned Mars missions.

eburacum45
2007-Oct-27, 06:00 PM
The Moon is the key to permanent habitation off the Earth. It is a low gravity source of metals, silicon and oxygen, and the surface can be used for solar power collection. There are even some reserves of thorium and uranium for fission, even perhaps He3 for fusion.

When and if we start to colonise the rest of the Solar Sytem, much of that colonisation will probably be carried out in ships made from lunar iron and aluminium, breathing lunar oxygen.

AtomicDog
2007-Oct-27, 06:05 PM
To elaborate on my feelings on the subject:

I love the Moon.

I am fifty-three years old, and for three decades I have been waiting for humankind to resume what we should never stopped - manned exploration of the Moon. It has been barely explored, and it is the perfect training ground for further manned exploration of the Solar System: Asteroids, Mars, Jovian and Saturnian satellites. I just cannot see a nation that is serious about deep space exploration not wanting to cut its teeth first on a target that is easy to get to and at the same time provides similar challenges to techniques and equipment as targets hundreds and thousands more difficult to reach.

Personally, I probably will not live to see boots on Mars. I probably will live to see boots on the Moon, and I intend to spend my time vicariously enjoying that base going up at Aitken Basin.

Drbuzz0
2007-Oct-27, 08:37 PM
This anti-lunar pattern in your threads - you must not like the moon very much.

I like the moon. The moon is great. I just don't see why it's the focus of everyone's damn space program.

Look, I also love covets, but considering that they're expensive, not very fuel efficient, only have two seats and don't drive well in bad conditions I would not want to focus all my funds on getting one until I can at least get a more practical car for general purpose use. Once I can aford a decent general purpose car and I have some extra money I'd consider buying one for spring weekend and sunny summer cruising.

The moon is a fascinating place with resources that may someday be necessary (not soon though) and where much can be learned. But would you want to do so at the expense of your more immediately practical space options?

gwiz
2007-Oct-27, 10:07 PM
Japan, a country which has begun a serious scientific space probe program on their own has focused much of their energy on sending lunar orbiters to survey the moon both for pure research and for a possible manned moon mission. They have not yet flown a manned mission of their own and they lack any heavy lift platforms which would be able to support manned missions at this time.
However, Japan is about to provide a major new laboratory for the International Space Station, launching next year.

India, a country who's recent technological expansion has established a thriving scientific community - but has not exactly helped eliminate poverty amongst the nearly one billion citizens, many of whom live bellow the poverty line - has just begun to develop it's own satellite launch capabilities and has a rather limited space flight record. They have stated that they are planning a lunar exploration program.
India has been launching satellites for a quarter of a century, almost entirely applications satellites for communications, weather observation and surface resources survey. What they have only just started doing is launching other nations' satellites commercially. I would think a lunar probe would form a pretty good ad for a nation's new launch services.

KaiYeves
2007-Oct-27, 11:35 PM
Because, quite frankly, it's COOL.
Why, as a kid, do you want to see what's under your bed, or over your neighbor's fence, or in the part of the building for the upper grades?
That's the reason why.

Grand_Lunar
2007-Oct-28, 12:49 AM
But would you want to do so at the expense of your more immediately practical space options?


Such as what?
The shuttle? Nope; very expensive to run for what it does.
The ISS? Maybe, but it really hasn't gotten us anywhere, aside from LEO.

Count Zero
2007-Oct-28, 01:11 AM
But would you want to do so at the expense of your more immediately practical space options?

We've been concentrating on the "more immediately practical space options" for 35 years. It's time to aim higher.


I like the moon. The moon is great. I just don't see why it's the focus of everyone's damn space program.

"If this capsule history of our progress teaches us anything, it is that man, in his quest for knowledge and progress, is determined and cannot be deterred. The exploration of space will go ahead, whether we join in it or not, and it is one of the great adventures of all time, and no nation which expects to be the leader of other nations can expect to stay behind in the race for space...

"There is no strife, no prejudice, no national conflict in outer space as yet. Its hazards are hostile to us all. Its conquest deserves the best of all mankind, and its opportunity for peaceful cooperation many never come again. But why, some say, the moon? Why choose this as our goal? And they may well ask why climb the highest mountain? Why, 35 years ago, fly the Atlantic? Why does Rice play Texas?

"We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win . . ."

It was true 45 years ago (http://www.jfklibrary.org/Historical+Resources/Archives/Reference+Desk/Speeches/JFK/003POF03SpaceEffort09121962.htm), and it is true today.

Warren Platts
2007-Oct-28, 02:27 AM
I think it's great - the more the merrier. But it would be nice if there was some cooperation, like with the ISS, to allow more to be accomplished with the money spent. Same with the planned Mars missions.
I like the more the merrier, but only because it sparks competition. The problem with the ISS is too many chefs in the same kitchen. It's best if each nation goes its own way. Each program will be run more efficiently, and there will be less dilly-dallying because the prestige that goes with being first won't be shared with everyone.

As for strategic reasons for going to the Moon, I still think it would make a great 3rd strike platform. :D

01101001
2007-Oct-28, 02:28 AM
One analyst's take: Guardian Unlimited: Plundering the moon (http://www.guardian.co.uk/comment/story/0,,2200256,00.html?gusrc=rss&feed=technology)


The new space race isn't focused on science or discovery, but is about exploiting lunar minerals

China certainly has strong political reasons for taking a tilt at the moon. On one level, its lunar programme is an expensive advertisement for economic prowess. As every Republican president since Ronald Reagan has demonstrated, politicians equate space with vision, even if the vision has little chance of being realised. This one does, however.
Yet, hidden beneath the expressions of patriotic pride in the Chang'e-1 probe's launch is evidence that this new space race will be different from the first. Examine the mission statement and you'll find the objectives given as creating maps and "analysing the chemical composition of lunar dust". Innocent-sounding science at first sight; on closer inspection, nothing of the sort.

Tucson_Tim
2007-Oct-28, 02:31 AM
I like the more the merrier, but only because it sparks competition. The problem with the ISS is too many chefs in the same kitchen. It's best if each nation goes its own way. Each program will be run more efficiently, and there will be less dilly-dallying because the prestige that goes with being first won't be shared with everyone.


You're probably right about that. I just wish you weren't.

Noclevername
2007-Oct-28, 03:17 AM
I like the moon. The moon is great. I just don't see why it's the focus of everyone's damn space program.


Because it's big, it's obvious, and politicians have simple minds. At least when it comes to planning longterm nonpolitical goals.

Count Zero
2007-Oct-28, 06:15 AM
The new space race isn't focused on science or discovery, but is about exploiting lunar minerals

I don't have a problem with that.

CuddlySkyGazer
2007-Oct-28, 07:40 AM
The purpose of manned-space exploration is the extension of the human social and economic sphere to the rest of the solar system. To have humans utilising local resources to build societies. The Moon is a good first step.

That's the 'vision' in the VSE. Whilst carrying this out, one may as well accrue any shorter-term benefits. These are perceived to be national prestige, national security, inspiration of youth, the development of the science and engineering base, and science itself. (These also tend to re-inforce each other.)

For countries other than the US, as NASA is apparently going anyway co-operation is one way, and that requires something to offer in exchange.

KaiYeves
2007-Oct-28, 01:08 PM
The new space race isn't focused on science or discovery, but is about exploiting lunar minerals
I don't have a problem with that.
I do, but nobody cares what I think.

Count Zero
2007-Oct-28, 01:33 PM
Well, it's not like there's a fragile ecosystem there. I mean, if you want to restore it to its pre-colonization state, you just bomb it with asteroids and wait for solar flares to irradiate the surface. The moon is the very apotheosis of a dead, blasted world. I'd rather we did more mining there and less on Earth.

(And yes, I do care what you think. You're intelligent, thoughtful and express your thoughts well. Furthermore, you're more likely to live on the Moon than I am, so you ought to have a say in what goes on there.)

A.DIM
2007-Oct-28, 02:27 PM
Obviously, no one's really sure humans have been there to begin with.

:D


Seriously though, it's the most accessible planetary body with potential resources which can be exploited both on and off planet Earth.

Zachary
2007-Oct-28, 04:24 PM
I think it shows an incredible maturity of society that we can spend god knows how many billions of £/$/€/whatever to do something purely 'for the hell of it'. When in history has that ever been the case? If we only spent resources on projects which had a clear short-term utility then humanity's pace of progress would be much slower than it is now.

Mankind throughout its evolutionary history has always been stuck on one body, in one gravity well. I think the pure fact that we're now technologically able to do otherwise is a fairly compelling reason itself to do it.

Humans are natural explorers. It's why people climb Everest and why god knows how many 19th century explorers spent years trekking around the arse-end of nowhere. Going to the Moon is just an extension of our underlying need to explore our surroundings.

Launch window
2007-Oct-28, 04:52 PM
Personally I've always believed that Mars is going to be a much better option for long term exploration and colonization.

The Moon however does have a few things going for it

We know what it takes to go to the Moon. Mankind has been there before, in 1969 the United States proved their dominance by landing Apollo-11, Russia also proved it could be done when they landed robotic missions for a sample return.

What happens if supplies are lost and they lose all their water. Re-Supplying a lunar base in case of emergency is much easier, Mars is years away from Earth. while the moon is only a couple days away

Ground control can respond to technical glitches and other problems almost instantly, look how they turned around Apollo-13. With Mars we've to wait about 4 mins for a response. What would happen if we sent five Americans to Mars and the whole crew was killed?

Time, money, and effort spent which will be required for Mars is going to be a heck of a lot greater for Mars than a mission on going to the moon. IMHO the VSE doesn't have enough funding for a Mars mission.

Lunar Telescopes, Radio dishes, experiments on the Moon can be manipulated live from Earth, Lunar solar arrays can be built and electricity beamed to Earth...with Mars we do not have any of these options

Noclevername
2007-Oct-28, 06:53 PM
We know a lot more about the surface of the Moon than any other extraterrestrial body. So there's less surprises-- and in space, "surprising" almost always equals "dangerous".

Ilya
2007-Oct-28, 08:34 PM
I like the moon. The moon is great. I just don't see why it's the focus of everyone's damn space program.

Look, I also love covets, but

"Thou shall not covet thy neighbor's wife's moon"

Noclevername
2007-Oct-28, 09:17 PM
Mostly it's a spitting* contest. Everone on Earth is familiar with the Moon. Everyone on Earth knows that a manned landing on it was considered a great accomplishment. And many hold up that accomplishment as a benchmark of space travel, because it's widely considered to be the greatest publicly celebrated space-related human endeavor. Public opinion is what makes politics go 'round.


*(substituted word)

KaiYeves
2007-Oct-28, 09:19 PM
I'd rather we did more mining there and less on Earth.
(And yes, I do care what you think. You're intelligent, thoughtful and express your thoughts well. Furthermore, you're more likely to live on the Moon than I am, so you ought to have a say in what goes on there.)
It's fine if we mine up there, but having that as the sole reason rather than science is not fine. I meant that nobody who would be in a position to do anything about how the moon is explored cares what I think, as I can't vote.

Humans are natural explorers. It's why people climb Everest and why god knows how many 19th century explorers spent years trekking around the arse-end of nowhere. Going to the Moon is just an extension of our underlying need to explore our surroundings.
Well said. I put it a little more domestically before.

Noclevername
2007-Oct-29, 12:17 AM
The new space race isn't focused on science or discovery, but is about exploiting lunar minerals


Where did you get that idea? The new Space Race (currently more like a Space Amble) is about prestige. There are no space programs currently active that have taken any steps toward mining, let alone made it their "main reason" to go to the Moon. There may be a few doodles on napkins but no one has incorporated it into any active program that I know of.

Count Zero
2007-Oct-29, 01:02 AM
It's fine if we mine up there, but having that as the sole reason rather than science is not fine.

Who says that one excludes the other? An awful lot of geology and geochemistry is done by oil & mining companies. The don't want to mine an area until they know what's there. The way that specific ores are deposited on the Moon is completely different from the water-based processes on Earth. The would-be miners will have to gain a good understanding before they even set-up their first major dig.

Ore recovery will be a whole 'nother area to research. How much of the material is in rock, and how much is in regolith? How much is the regolith compacted, and how deep? How do you do large-scale digging & drilling in a vacuum? What does this do to men & machinery?

Metallurgists will then have to figure out how to turn ore into manufactured metals in low-gravity vacuum forges. The list goes on.

If all we do is go to the Moon to mine, this would still result in a scientific and technological renaissance. But like I said, it won't be all we do, in part because of the spin-off benifits. If we have the capability to move mining & manufacturing equipment to the Moon, then we can move a lot of other things there, too (starting with whatever science package you want to name).


I meant that nobody who would be in a position to do anything about how the moon is explored cares what I think, as I can't vote.

But you will be able to, before the CEV ever flies. :)

ASEI
2007-Oct-29, 02:30 AM
If you want to send anything anywhere in space, you need reaction mass. If you want to run an orbital colony or something, it will still need a stream of matter coming from somewhere and going to somewhere to sustain itself. The moon may be lacking a few key things, but it can provide metal and reaction mass.

And if it can import those few key things (hydrogen, light volatile elements, ect), then there's no reason it couldn't be colonized just as easily as Mars.

If you had a fuel base on the moon turning out tanks of LOX/powdered metal, you could use those as your fuel supply to send things elsewhere in the solar system, rather than needing to launch all the fuel from earth (half-again as much fuel as you used to get into orbit! Orbit may be half-way to anywhere, but it's only half-way)

If you set up a base with a good manufacturing capacity, able to create most components of sattelites and rocketry (tankage, ect) then you would be able to project a massive space effort into interplanetary space. Without such a base for shipbuilding, it's hard to see how you'll accomplish colonizing mars, or moving the mass required to seriously get people elsewhere.

I see the moon as a potential shipyard for interplanetary expansion, in other words.

KaiYeves
2007-Oct-30, 01:30 AM
But you will be able to, before the CEV ever flies.
You're right. If whoever gets elected in '08 kills Orion, I will drop them like they are hot when they go for re-election.

Noclevername
2007-Oct-30, 04:07 AM
Without such a base for shipbuilding, it's hard to see how you'll accomplish colonizing mars, or moving the mass required to seriously get people elsewhere.


Or several such bases, both Lunar and asteroidal. Although the Moon is a shorter trip away if an emergency should arise.

EDIT: And it's closer to those who will want to go into space.

Argos
2007-Oct-30, 12:43 PM
Why people go to the Moon? because it is there. ;)

Doodler
2007-Oct-30, 03:28 PM
Why people go to the Moon? because it is there. ;)

Like the way this man thinks. :)

KaiYeves
2007-Oct-30, 07:38 PM
Like the way this man thinks.
Pst! His real name is George Mallory.

Noclevername
2007-Oct-30, 10:01 PM
The arguments for Lunar visits that the average BAUTer would support, are no doubt not the same ones you'd need to convince governments or wealthy backers that it's worth the investment.

Drbuzz0
2007-Oct-30, 11:18 PM
So then the whole point of going to the moon is to exploit its resources? Great. Don't you think that maybe before going there to scope them out (since we already have some idea what is there), one might want to establish whether there is a way that you could actually get them back to earth... or for that matter build some spacecraft out of them for a cost that is less than just mining them here.

The earth is nowhere near depleted of usable metal or other mineral reserves... especially considering the sea floor which is tough to get them from (but not nearly as tough as the moon).

The question is this: What do you gain from going to the moon? You necessitate a large launch platform and purpose built hardware which isn't always going to be of much use for other things.


You can launch a space station, launch a bunch of research satellites, do several manned servicing missions, send multiple probes to planets, develop better, safer cheaper launch systems and do enumerable other things for the same price as a single flag-sticking mission to the moon.

The expense is always high and the benifits are unknown and probably small by comparison.


I'm getting tired of this whole "The shuttle just gets into LEO orbit.. we've been doing LEO orbit for the past 30 years."

Yes... we have... and STILL SUCK AT IT AS BADLY AS WE DID 30 YEARS AGO... worse even!

I'd rather have the ability to go to drive around the country and do it well and in comfort than take a couple of trips to antartica to look at the ice.... yes I know Antarctica has interesting biology and you can study climate there.

AtomicDog
2007-Oct-30, 11:26 PM
You've asked me why I want to go to the moon. I've told you. I just want to see us go. So do a lot of other people, and we are willing to have our governments carry out our wishes. I'm sorry you can't accept that answer, but there it is.

Noclevername
2007-Oct-30, 11:30 PM
So then the whole point of going to the moon is to exploit its resources? Great. Don't you think that maybe before going there to scope them out (since we already have some idea what is there), one might want to establish whether there is a way that you could actually get them back to earth... or for that matter build some spacecraft out of them for a cost that is less than just mining them here.

The earth is nowhere near depleted of usable metal or other mineral reserves... especially considering the sea floor which is tough to get them from (but not nearly as tough as the moon).Getting Lunar resources back to Earth would be a waste. Getting them into space-- at far less energy cost than launching from Earth-- would be the point of Lunar Mining.


The question is this: What do you gain from going to the moon? You necessitate a large launch platform and purpose built hardware which isn't always going to be of much use for other things.


You can launch a space station, launch a bunch of research satellites, do several manned servicing missions, send multiple probes to planets, develop better, safer cheaper launch systems and do enumerable other things for the same price as a single flag-sticking mission to the moon.

The expense is always high and the benifits are unknown and probably small by comparison.


I'm getting tired of this whole "The shuttle just gets into LEO orbit.. we've been doing LEO orbit for the past 30 years."

Yes... we have... and STILL SUCK AT IT AS BADLY AS WE DID 30 YEARS AGO... worse even!

I'd rather have the ability to go to drive around the country and do it well and in comfort than take a couple of trips to antartica to look at the ice.... yes I know Antarctica has interesting biology and you can study climate there.


Ah, now you're talking about something different. Now you're talking about going directly to the Moon from Earth, which I agree is indeed a bad idea. In fact I doubt you'd find many people on BAUT who'd rather have one moonshot than a permanent waystation to the rest of the Solar System. But that's not how it is. The politicians in charge of these things want to do it their way, and they control the purse strings. The powers that be want their Moon Rocket, and not for mining resources, but just to say that they can. And, until that changes, we all just have to live with it.

Drbuzz0
2007-Oct-31, 03:57 AM
Getting Lunar resources back to Earth would be a waste. Getting them into space-- at far less energy cost than launching from Earth-- would be the point of Lunar Mining.



Yes, that's true. But I'm still thinking this is more than... premature. Especially for countries which are trying to establish their manned space program. When we went to the moon we went for broke because of the cold war and the fact that the president who proposed it was something of a legend having been assassinated. It's just... not really the most efficient way to develop your space technology to have a goal like going to the moon. Especially when your program isn't prepared to necessarily go further.

I've said that it's easier to go to Mars from a base on the moon than from earth. But it's easier to go to Mars from earth than to go to the moon first, build a lunar base there, establish the methods for mining the moon, build a spacecraft on the moon and then finally go to the moon and then onto mars..



Ah, now you're talking about something different. Now you're talking about going directly to the Moon from Earth, which I agree is indeed a bad idea. In fact I doubt you'd find many people on BAUT who'd rather have one moonshot than a permanent waystation to the rest of the Solar System. But that's not how it is. The politicians in charge of these things want to do it their way, and they control the purse strings. The powers that be want their Moon Rocket, and not for mining resources, but just to say that they can. And, until that changes, we all just have to live with it.

I'm of the opinion that the first thing that must be done to get to the point where space technology can live up to it's full potential is to build an efficient and relatively sustainable means of getting there and then branch out.

That's what the shuttle would have been - until the DOD got involved and made some ridiculous criteria, then the original plans got axed and the funding was changed a half-dozen times and then they ended up with something that had no relationship to what it was supposed to be: A way to "Shuttle" things into space such that impromptu and frequent missions could be held.


The National Aerospace Plane is dead. Nasa hasn't shown any interest in the two-stage shuttle concept (ramjet lifter and parasite orbiter). They've ditched Venturestar... and not only the Venturestar design, but the whole basic concept.

They've shown no interest in a BigDumbBooster + A Multiuse Orbiter. They've completely abandoned SSTO. The multi-purpose flyback firststage is dead in the water.

Clearly NASA has thrown their hands up in the air on that whole line of research.

They don't care that you'll never go to space. That I never will. That only a few astronauts will ever go and maybe a few billionaires. They don't care that scientists have to wait years to have an experiment flown and that if it goes wrong, they never get a second chance. They don't care that only multi-billion dollar corporations can afford to launch satellites. They don't care that the space station will never live up to its full potential. They don't care that the price per KG to orbit will not be significantly less. They don't care that a manned space flight will never be launched on reasonably short notice. They don't care that many scientific payloads will not get flown. They don't care that every satellite must be made to extreme tolerances of reliability, because if it fails, there is no way to recover it or do another launch at a reasonable cost.

They don't care that 30 years of "Cheap safe routine" promises have been broken. No, they could not care less. To them it's too important to send an expedition to the moon to collect rocks and plant a flag to ever consider developing a new capability or opening space to science and enterprise.

:cry::cry::cry::cry::cry::cry:

Noclevername
2007-Oct-31, 05:51 AM
Leaving the future of space travel in the hands of politicians is sort of like leaving a baby in a tree. Luckily others are now taking up the challenge and someday, we won't need to rely on their whims anymore. And, for purely economic reasons, private spacers will have to build stepping stones rather than blow money on massive, showy, one-shot surface-to-surface jumps.

cjl
2007-Oct-31, 09:09 AM
Let's see here:

Ramjet/parasite concept:
Far more expensive for the same payload, not much benefit

SSTO:
Extremely expensive per payload, almost no usable payload compared to vehicle mass

Pretty much every idea mentioned, while pretty on paper, ignores the basic physics of current spaceflight. With the current propulsion technology, any attempts to reuse more than perhaps a simple first stage or a capsule will add complexity and cost, rather than making it cheaper. It may be nice to think about other things, but they cannot be a reality (especially any decent SSTO) until the propulsion technology and exhaust velocities are VASTLY improved over their current level.

ASEI
2007-Oct-31, 12:09 PM
Hmmm - what about a multi-stage hybrid rocket, where you have a central LOX tank that stays with the main vehicle most of the way, and a large number of mass-produced rubber fuel cylinders? I'm somewhat interested in that concept, and I'll be doing some trade studies to see if something like that could actually make it into orbit.


It may be nice to think about other things, but they cannot be a reality (especially any decent SSTO) until the propulsion technology and exhaust velocities are VASTLY improved over their current level. NERVA had 1000 sec Isp. It could probably do SSTO.

AtomicDog
2007-Oct-31, 12:15 PM
It is not that NASA does not care - it is that the Cold Equations do not care.

jlhredshift
2007-Oct-31, 12:20 PM
Ahh...to be a Type I civilization.:)

The Nina, Pinta, and Santa Maria, now there was a well funded expedition that knew exactly where they were going and what they were going to do when they got there. And by the way, there were human losses en-route and when they got there. But it opened the door to a whole new era of human accomplishment. Still, it took 200 years for colonization by regular folks to start en masse. Ships, navigation all got better but human losses still occurred. We pressed on. Wars, threats of wars, drove technology; it still drives technology. Doing the hard stuff expedites knowledge creation.

It is not that a nations prestige would be lessened by some other nation being on the Moon, its that their technology would be behind that of the successful country. That translates to economic power here on Earth, which is the driving force currently operable on this planet.

Noclevername
2007-Oct-31, 05:09 PM
The problem is not one of technology but of capacity. Building simple LEO boosters in large numbers is not beyond the means of most First World nations, which regularly spend larger amounts for little or no return. It's just a matter of priorities.

ADDED: This would enable the construction of a fuel depot in LEO, and ferries to take anyone to the Moon or nearly anywhere else, for that matter.

IsaacKuo
2007-Oct-31, 07:00 PM
Hmmm - what about a multi-stage hybrid rocket, where you have a central LOX tank that stays with the main vehicle most of the way, and a large number of mass-produced rubber fuel cylinders? I'm somewhat interested in that concept, and I'll be doing some trade studies to see if something like that could actually make it into orbit.

I love hybrid rockets, but they (currently) lack the specific impulse necessary to be anything more than first stage boosters. The optimum specific impulse is for the average exhaust velocity to match the delta-v spent so far. Thus, you may use low specific impulse for the first stage, but not the later stages.

Still, this reminds me of Otrag (http://www.astronautix.com/lvs/otrag.htm), which greatly appeals to my sensibilities.


NERVA had 1000 sec Isp. It could probably do SSTO.

NERVA wasn't capable of 1 gee acceleration. It couldn't even lift itself off the ground, much less do SSTO.

KaiYeves
2007-Nov-01, 01:09 AM
Ahh...to be a Type I civilization.
Oh yeah! That would be the best thing since no-homework passes!
Here is a story I think I should share.
When Ben Franklin was in Paris, he saw a demonstration of one of the first hot-air balloons.
One spectator asked:
"Yeah, sure, it flies. But, Dr. Franklin, what is the use of it?"
"Someday, I think people may fly everywhere. After all, what good is a newborn baby?"

ASEI
2007-Nov-01, 02:07 AM
The optimum specific impulse is for the average exhaust velocity to match the delta-v spent so far. Well it might not be optimimum in terms of lowest possible propellant mass, but that's not really a consideration (as long as it doesn't end up being something ridiculous like millions of tons and thousands of stages). Rubber is cheap. (Or most other propellants for that matter) Tankage is cheap. (this is part of why SSTO is irrelevant). What gets expensive is the turbomachinery and orbiter hardware, and especially the engineering hours necessary to get the vehicle constructed/refurbished and ready for launch. The time costs a great deal of money - time spent fiddling, time spent fixing, time spent obsessing over parts designed to too tight a tolerance.

jlhredshift
2007-Nov-01, 02:40 AM
The problem is not one of technology but of capacity. Building simple LEO boosters in large numbers is not beyond the means of most First World nations, which regularly spend larger amounts for little or no return. It's just a matter of priorities.

ADDED: This would enable the construction of a fuel depot in LEO, and ferries to take anyone to the Moon or nearly anywhere else, for that matter.

But it is one of technology, because of the need, real or not, of being human rated and done within whatever resource constraint that is artificially imposed. Give the members of just this board unlimited resources and we could go to the Moon, Mars, or where ever.

Noclevername
2007-Nov-01, 02:46 AM
But it is one of technology, because of the need, real or not, of being human rated and done within whatever resource constraint that is artificially imposed. Give the members of just this board unlimited resources and we could go to the Moon, Mars, or where ever.

Man-rated spacecraft are already in existence and have been for some time.

Yes, it is a matter of "resource constraint that is artificially imposed". And the needed resources for doing so don't need to be anywhere near "unlimited". Just a matter of diverting a few of them from other presently unprofitable or wasteful uses of resources.

But I can't say how likely that scenario is, because it depends entirely on the whims of large groups of people.

jlhredshift
2007-Nov-01, 02:57 AM
Man-rated spacecraft are already in existence and have been for some time. .

Of course they have, but not for going to the moon today. The rules and constraints have changed because we know more now. We have to build a new vehicle that would meet saftey constraints of todays knowledge.


Yes, it is a matter of "resource constraint that is artificially imposed". And the needed resources for doing so don't need to be anywhere near "unlimited". Just a matter of diverting a few of them from other presently unprofitable or wasteful uses of resources..

I agree.


But I can't say how likely that scenario is, because it depends entirely on the whims of large groups of people.

I agree, sadly true.

IsaacKuo
2007-Nov-01, 03:17 AM
Well it might not be optimimum in terms of lowest possible propellant mass, but that's not really a consideration (as long as it doesn't end up being something ridiculous like millions of tons and thousands of stages).

The mass can be a significant consideration, depending on the specific impulse in question.

For example, to provide 10km/s delta-v with 380sec hydrogen/lox requires a mass ratio of perhaps 14. But to provide 10km/s with 290sec kerosene/lox requires a mass ratio of perhaps 31. If your cheap hybrid rocket provides only, say, 260sec specific impulse, the required mass ratio could by 45.

Of course, liquid hydrogen has its own problems which can make kerosene a more practical fuel to use. But I'm not so sure a hybrid rocket provides compelling advantages over kerosene.


What gets expensive is the turbomachinery and orbiter hardware, and especially the engineering hours necessary to get the vehicle constructed/refurbished and ready for launch. The time costs a great deal of money - time spent fiddling, time spent fixing, time spent obsessing over parts designed to too tight a tolerance.

That's what I like so much about OTRAG. No turbomachinery, just pressure fed mass produced disposable kerosene rockets. No fancy actively cooled nozzles, just disposable ablative nozzles.

Noclevername
2007-Nov-01, 04:19 AM
Of course they have, but not for going to the moon today. The rules and constraints have changed because we know more now. We have to build a new vehicle that would meet saftey constraints of todays knowledge.



A large, but not insurmountable, challenge.

ASEI
2007-Nov-01, 10:22 AM
Of course, liquid hydrogen has its own problems which can make kerosene a more practical fuel to use. But I'm not so sure a hybrid rocket provides compelling advantages over kerosene.


It might not. Just exploring an avenue. The main advantage I was thinking of was the ability to store these fuel cylinders practically indefinitely, stockpiling them for when you need a launch, and produce a stack ready for launch with minimum processing. But kerosene stores easily too.

Also, you might be able to keep the gas generator and turbomachinery up top with the re-entering orbiter capsule, and attempt to reuse them, since the pressurized LOX would be injected at the top of the rubber fuel cylinders.

jlhredshift
2007-Nov-01, 01:06 PM
A large, but not insurmountable, challenge.

I agree, but as long as the funding is governmental, and exposed to "whims", risk abatement will accelerate both the cost and mass of the vehicle.

Edit to add: The thought just occurred to me; what would the political response from the world be if a privately funded mission landed on the Moon?

danscope
2007-Nov-01, 05:26 PM
I agree, but as long as the funding is governmental, and exposed to "whims", risk abatement will accelerate both the cost and mass of the vehicle.

Edit to add: The thought just occurred to me; what would the political response from the world be if a privately funded mission landed on the Moon?

Hi, You mean Richard Branson and Bill Gates buying an old Saturn V at garage sale prices and fixing it up? :)
Hmmmm.

Noclevername
2007-Nov-01, 07:41 PM
Edit to add: The thought just occurred to me; what would the political response from the world be if a privately funded mission landed on the Moon?

I don't know about the political response, but my response would be to stand up and cheer!

:dance::dance::dance::dance::dance:

KaiYeves
2007-Nov-01, 10:12 PM
I don't know about the political response, but my response would be to stand up and cheer!
I would run outside to look at the moon and, paraphrasing a witness to the First Flight at Kitty Hawk, scream:
"They've done it! They've done it! God bless them, they've done it!"
And then I would run back inside, grab some paper and start writing a letter:
"Dear Sir, my name is Kai, I am a student who is very interested in what you have done. My mom says I should get a summer job..."

Noclevername
2007-Nov-01, 10:23 PM
...So, in answer to the question "What's with everyone wanting to go to the moon?", all I can say is, it's not everyone... just everyone who can afford to go right now.

Drbuzz0
2007-Nov-02, 01:27 AM
Let's see here:

Ramjet/parasite concept:
Far more expensive for the same payload, not much benefit

SSTO:
Extremely expensive per payload, almost no usable payload compared to vehicle mass

Pretty much every idea mentioned, while pretty on paper, ignores the basic physics of current spaceflight. With the current propulsion technology, any attempts to reuse more than perhaps a simple first stage or a capsule will add complexity and cost, rather than making it cheaper. It may be nice to think about other things, but they cannot be a reality (especially any decent SSTO) until the propulsion technology and exhaust velocities are VASTLY improved over their current level.

Oh not this argument again. Is this another claim that "You cannot make a reusable cost effective space system with current technology so we should not even try."

Nasa has thrown in the towl and decided that they are committed to the single-shot capabilities which have existed since the 1960's.

If we're just going to stick with the standard rockets we always have then I consider it a complete waste.

What will mean "cheap sustainable reliable" space transport? I don't know. Maybe SSTO. Maybe a parasitic spaceplane. maybe a single module spaceplane. Maybe a "Boosted SSTO" maybe a "Flyback first stage" or maybe something else...

Whichever approach is going to achieve is irrelevant because nasa has decided not to bother with even trying anymore.

They've decided that the initial investment in developing something is not worth the new capability it would offer thereafter.

As a citizen of the United States, I'm dissatisfied with this and I'll be very apt to vote for any politician who expresses the same opinion as I have. If this is what nasa wants then the agency should be DISBANDED. The unmanned space research program can be handled by the National Laboratory system of the DOE. The launch systems can be handled by the Airforce and private contractors.


If it's impossible to achieve what nasa has promised for 30 years then fair enough... it's impossible. But if that's the case then I see no reason to burn more money on NASA. "We tried. We failed. It turns out we can't do it. Time to cut our losses"

01101001
2007-Nov-02, 01:32 AM
Nature editorial: Because it's there: An Asian Moon race is neither particularly worrying nor especially inspiring (http://www.nature.com/nature/journal/v450/n7166/full/450002a.html):


In the 1960s and 1970s, the United States and Soviet Union mounted dozens of missions to the Moon, orbiting it, crashing into it and landing softly on it. They even went so far as to return samples from it, either with a little help from some humans on hand or, in the Soviet case, without. Subsequently, neither spacefaring power touched the place for almost 20 years.
[...]
But for aspiring nations that have neither been there nor done that, the Moon has a great advantage over other objects of celestial study. Although only moderately interesting, it is very close and relatively easy to reach.
[...]
It is easy to exaggerate the extent to which this constitutes a new Moon race. National rivalries and prestige definitely play a part in some of these programmes: China's, in particular, is both touted by the government and appreciated by the population as evidence of national accomplishment and ambition. But the idea sometimes floated that this activity reflects a new perception of some sort of value in the Moon itself is wide of the mark.

Noclevername
2007-Nov-02, 01:39 AM
Even single use multistagers could be made far cheaper and more reliable than they are now. But not in the hands of NASA, whose hands are tied by Congressional purse strings. Blaming NASA itself is wasted emotion, as they aren't the ones in charge of their own destiny. It's the politicos who ultimately call the shots, and then change them every election, which is why we're in the mess we are today.

cjl
2007-Nov-02, 05:00 AM
Oh not this argument again. Is this another claim that "You cannot make a reusable cost effective space system with current technology so we should not even try."

Nasa has thrown in the towl and decided that they are committed to the single-shot capabilities which have existed since the 1960's.

If we're just going to stick with the standard rockets we always have then I consider it a complete waste.

What will mean "cheap sustainable reliable" space transport? I don't know. Maybe SSTO. Maybe a parasitic spaceplane. maybe a single module spaceplane. Maybe a "Boosted SSTO" maybe a "Flyback first stage" or maybe something else...

Whichever approach is going to achieve is irrelevant because nasa has decided not to bother with even trying anymore.

They've decided that the initial investment in developing something is not worth the new capability it would offer thereafter.

As a citizen of the United States, I'm dissatisfied with this and I'll be very apt to vote for any politician who expresses the same opinion as I have. If this is what nasa wants then the agency should be DISBANDED. The unmanned space research program can be handled by the National Laboratory system of the DOE. The launch systems can be handled by the Airforce and private contractors.


If it's impossible to achieve what nasa has promised for 30 years then fair enough... it's impossible. But if that's the case then I see no reason to burn more money on NASA. "We tried. We failed. It turns out we can't do it. Time to cut our losses"
It is also the truth. If you truly are interested in a massive improvement in current launch capability, rather than ranting on launch vehicles, perhaps you should look more into the propulsive technologies involved. What we absolutely should look into (and in many ways we are looking in to) are new propulsive methods. Unfortunately, none so far have been both more efficient than current methods and capable of generating enough thrust to lift themselves off the ground.

Noclevername
2007-Nov-02, 05:17 AM
We don't need more advances. We need more lift capacity, even if it's done by mass producing a slightly less efficient existing design. The fuel or the stages are not the major sources of money woes. Costs are artificially high because of the present political/economic monopolies.

IsaacKuo
2007-Nov-02, 05:21 AM
Laser thermal will be able to be both efficient and capable of lifting off the ground. Someday. There's the minor little detail of needing a terribly powerful laser a few orders of magnitude more powerful than what we have so far.

The good news, of course, is that we're making amazing progress in high powered laser technology year after year.

Van Rijn
2007-Nov-02, 07:19 AM
Let's see here:

Ramjet/parasite concept:
Far more expensive for the same payload, not much benefit

SSTO:
Extremely expensive per payload, almost no usable payload compared to vehicle mass

Pretty much every idea mentioned, while pretty on paper, ignores the basic physics of current spaceflight. With the current propulsion technology, any attempts to reuse more than perhaps a simple first stage or a capsule will add complexity and cost, rather than making it cheaper. It may be nice to think about other things, but they cannot be a reality (especially any decent SSTO) until the propulsion technology and exhaust velocities are VASTLY improved over their current level.

If there is a high flight rate, a reusable two stage could make sense, versus throwing away a stage every time.

Larry Jacks
2007-Nov-02, 04:05 PM
I'm of the opinion that the first thing that must be done to get to the point where space technology can live up to it's full potential is to build an efficient and relatively sustainable means of getting there and then branch out.

That's what the shuttle would have been - until the DOD got involved and made some ridiculous criteria, then the original plans got axed and the funding was changed a half-dozen times and then they ended up with something that had no relationship to what it was supposed to be: A way to "Shuttle" things into space such that impromptu and frequent missions could be held.

Those "ridiculous criteria" that the DOD imposed had to do with being able to launch the satellites that the DOD needed launching. Some of them are quite big and heavy so the booster needed the ability to carry those loads. Sure, the DOD could've dropped their "ridiculous criteria" but then the Shuttle would've been useless for their needs.

Even single use multistagers could be made far cheaper and more reliable than they are now. But not in the hands of NASA, whose hands are tied by Congressional purse strings. Blaming NASA itself is wasted emotion, as they aren't the ones in charge of their own destiny. It's the politicos who ultimately call the shots, and then change them every election, which is why we're in the mess we are today.

The key to lowering the cost to orbit is to increase the flight rate. If you spend a lot of money developing a booster and then only fly it a few times each year, the cost per flight is going to be high. That's one reason why so many people like me question NASA's choice to spend billions developing the Ares I and V. The Ares I in particular doesn't seem justified because it duplicates (barely) the capacity of existing designs. As a result, both the existing designs and the Ares I will only be flown a few times each year (at most). That drives up the costs for everyone. I'll be very suprised if the Ares V ever flies more than twice a year. It's going to be an extremely expensive rocket.

In the 1970s, NASA tried to put the expendable booster companies out of business by saying that the Shuttle will meet everyone's needs. They used tax money to heavily subsidize some satellite launches and undercut the expendable market. Following the Challenger accident, NASA was ordered to stop launching satellites with the Shuttle excepting those government satellites that were already in the schedule. NASA itself was ordered to use commercial launch vehicles for space launches other than Shuttle missions. I agreed with this decision then and still do. Government agencies shouldn't be competing with industry, especially when the agencies require heavy subsidizies to be competitive.

Noclevername
2007-Nov-02, 05:45 PM
It's very frustrating. I remember when I was a kid, the Shuttle was being hyped as the "workhorse of space". Well, the old grey mare, she ain't what she used to be.

KaiYeves
2007-Nov-02, 07:53 PM
Well, the old grey mare, she ain't what she used to be.
Rosinante?

Noclevername
2007-Nov-02, 08:10 PM
Rosinante?

More like a high-maintainance, prancing political show pony. Who needs constant veterinary attention just to stay alive, and an entire crew of high-paid trainers. Plus only eating a special very expensive feed only available from a single store.

KaiYeves
2007-Nov-02, 08:10 PM
More like a high-maintainance, prancing political show pony. Who needs constant veterinary attention just to stay alive, and an entire crew of high-paid trainers. Plus only eating a special very expensive feed only available from a single store.
But at least her rider doesn't try to kill windmills.

Noclevername
2007-Nov-02, 08:16 PM
But at least her rider doesn't try to kill windmills.

Yes, I guess that's one for the "plus" column.

KaiYeves
2007-Nov-04, 10:31 PM
Yes, I guess that's one for the "plus" column.
Although quite Quixotic! ;-)

Count Zero
2007-Nov-05, 02:03 AM
[b]Although quite Quixotic! ;-)[/i]

I've often wondered how to pronounce that. Is it "kwik-zot-ik" or "kee-hoe-tik"?

Noclevername
2007-Nov-05, 03:31 AM
It's KEE-zo-tike. ;)

Or kew-eye-zho-tik.

MentalAvenger
2007-Nov-05, 03:44 AM
It is also the truth. If you truly are interested in a massive improvement in current launch capability, rather than ranting on launch vehicles, perhaps you should look more into the propulsive technologies involved. What we absolutely should look into (and in many ways we are looking in to) are new propulsive methods. Unfortunately, none so far have been both more efficient than current methods and capable of generating enough thrust to lift themselves off the ground.Ever watch a launch? The rocket (or STS) sits there on a pillar of flame for quite a while, accelerating slowly at first, and finally, after burning off thousands of pounds of propellant, begins to move at a velocity greater than that achieved by a Yugo.

Come on, people, the solution is obvious. A Maglev Rail launch assist could reduce the propellant required by about one-third at least. Send the vehicle up the side of a mountain on a cradle, propelled by electricity from the ground. Get it up to about MaxQ and then let the rockets take over.

Noclevername
2007-Nov-05, 03:54 AM
Come on, people, the solution is obvious. A Maglev Rail launch assist could reduce the propellant required by about one-third at least. Send the vehicle up the side of a mountain on a cradle, propelled by electricity from the ground. Get it up to about MaxQ and then let the rockets take over.
Who will you get to pay for it?

MentalAvenger
2007-Nov-05, 06:13 PM
Everyone that saves a LOT of money on fuel can spend a little money to use the rail launch.

Noclevername
2007-Nov-05, 06:22 PM
Everyone that saves a LOT of money on fuel can spend a little money to use the rail launch.

I mean, to build it in the first place, not to use? What would be the construction costs, as well as maintainance costs, and what companies and/or governments have expressed an interest* in doing so? What would be the energy reqirements?



*To the point of actually comitting money, I mean.

IsaacKuo
2007-Nov-05, 07:07 PM
Maglev launch from Earth hurts more than it helps. The fuel tanks and payload of the rocket need to survive strong gee forces, which will make them heavier and more expensive. Even if you get a good speed boost, you're going to suffer horrible losses from atmospheric drag. There's a good reason why rockets launch upward at a high angle and then turn nearly horizontal to add on orbital speed--it's to get out of the atmosphere while the speed is still low enough to not suffer excessive drag.

So, let's consider a maglev which reduces the fuel costs by maybe 1/3. This maglev boosts the rocket up to 5km/s at a mere 5gees (so as to only modestly increase the fuel tank and payload mass). The length of the maglev is 250km, or around the width of Mississippi. This is 8 times the length of the Shanghai maglev, which cost around a billion dollars. So, this 250km maglev might optimistically cost 8 billion dollars. This is the cost of maybe 50 Delta IV launches. Assuming the opertional costs of the maglev are ZERO, it'll pay for itself after the equivalent of around 150 Delta IV launches. More realisticly, it might only shave 5% off of the launch costs, so it'll pay for itself after the equivalent of around 500 Delta IV launches.

Even more realisticly, this maglev will cost much more per kilometer than the Shanghai maglev--after all, it needs to reach ten times as much velocity. Let's assume optimistically that the costs per kilometer are only ten times as much. This means it'll take 5000 Delta IV launches for the system to pay for itself.

But wait--there's air resistance. The maglev will be fighting 5km/s worth of drag in the thickest part of the atmosphere. It will likely cost MORE per launch than a pure rocket. Alternatively, the maglev could use a large vacuum tube. This means it costs even more per kilometer...let's be nice and only boost the cost per kilometer by a mere 10x factor. That means it'll take 50,000 Delta IV launches before the system pays for itself.

Now, consider that launch demand is so low that Delta IV was pulled from the commercial market.

transreality
2007-Nov-05, 10:30 PM
our country just spent 6 billion on two dozen crappy fighter jets, they are hardly backed by a commercial case. That money could have kickstarted a nice space programme.

Romanus
2007-Nov-05, 10:36 PM
<<More like a high-maintainance, prancing political show pony. Who needs constant veterinary attention just to stay alive, and an entire crew of high-paid trainers. Plus only eating a special very expensive feed only available from a single store.>>

LOL.

Singular
2007-Nov-05, 10:46 PM
The arguments for Lunar visits that the average BAUTer would support, are no doubt not the same ones you'd need to convince governments or wealthy backers that it's worth the investment.

True, and I often read about the stupidity of politicians (not so much wealthy backers) here for this reason. Apparently smart politicians would provide unlimited funding without asking any questions.

Singular
2007-Nov-05, 10:54 PM
And, for purely economic reasons, private spacers will have to build stepping stones rather than blow money on massive, showy, one-shot surface-to-surface jumps.

That's odd. I keep reading about how private spacers will do whatever the membership here wants them to do. You mean they'll pursue their own economic interests? How awful.

MentalAvenger
2007-Nov-05, 11:22 PM
I mean, to build it in the first place, not to use? What would be the construction costs, as well as maintainance costs, and what companies and/or governments have expressed an interest* in doing so? What would be the energy reqirements?The construction costs would be high, but they wouldn’t be anywhere near the costs of most other aerospace projects. A Mag-Lev Rail Launch Assist, or even a Rail Launch Assist, is a very straightforward design, using materials and technologies we have available today.

Again, if something is not presented to those companies and/or governments, they can hardly be expected to express interest in it. IMO, a serious feasibility study should be done on it.

Remember, this isn’t just about saving fuel. The less fuel the vehicle has to carry, the smaller and lighter it can be, even further reducing the fuel needed. The object is to impart significant initial velocity, where the rocket burns a LOT of fuel for a small gain in velocity. Run the rail as steeply as possible up a mountain, to about 20,000 ft. (there are 3157 climbable peaks over 19,685 ft). At that point, the atmospheric pressure is less than half that at sea level (about 46.61 kPa A). For the STS, that would also be more than half way to MaxQ (about 35,000 ft).

MentalAvenger
2007-Nov-05, 11:28 PM
Maglev launch from Earth hurts more than it helps. In your opinion.


yadda, yadda, yadda………so it'll pay for itself after the equivalent of around 500 Delta IV launches.Nice Strawman you have there.


yadda, yadda, yadda………This means it'll take 5000 Delta IV launches for the system to pay for itself.Ooooooooo…….the Strawman is getting bigger and even less relevant.


yadda, yadda, yadda………That means it'll take 50,000 Delta IV launches before the system pays for itself.Good grief, the Strawman just got so big it created a total eclipse of the Sun! I believe that is a new record.

IsaacKuo
2007-Nov-05, 11:55 PM
The construction costs would be high, but they wouldn’t be anywhere near the costs of most other aerospace projects.

How much do you think it would cost, vaguely? I give an optimistic number of 800 billion dollars.


Remember, this isn’t just about saving fuel. The less fuel the vehicle has to carry, the smaller and lighter it can be, even further reducing the fuel needed. The object is to impart significant initial velocity, where the rocket burns a LOT of fuel for a small gain in velocity.

The small amount of "wasted" fuel is more than made up for by reducing the weight of the fuel tanks and payload. Higher gee forces means heavier structures. This is also the reason why civilian aircraft don't use catapult launch like carrier jets do. They'd rather burn some extra fuel slowly accelerating when the jets are least efficient (at low speed), than lug around all the extra mass of the strengthening required to accept a catapult launch.


Run the rail as steeply as possible up a mountain, to about 20,000 ft. (there are 3157 climbable peaks over 19,685 ft). At that point, the atmospheric pressure is less than half that at sea level (about 46.61 kPa A). For the STS, that would also be more than half way to MaxQ (about 35,000 ft).

Altitude gain represents less than a twentieth of the energy costs to get to orbit. Most of the kinetic energy required goes into boosting up to orbital speed. The minimal gain for starting at a higher altitude is the reason why we don't launch rockets from the top of mountains. You'd think it would be a big benefit, but it isn't.

Noclevername
2007-Nov-06, 01:16 AM
The construction costs would be high, but they wouldn’t be anywhere near the costs of most other aerospace projects.

High isn't a number.

MentalAvenger
2007-Nov-06, 03:19 AM
How much do you think it would cost, vaguely? I give an optimistic number of 800 billion dollars.Interesting. Your 80 billion dollar estimate magically multiplied by ten again. In any case, as noted, I wasn’t talking about a 250km Mag_Lev rail like your Strawman was. Starting at sea level, a 20,000 ft mountainside would support a track about 8.6 km (5.35 miles) long.

How much would it cost? I don’t know.


The small amount of "wasted" fuel is more than made up for by reducing the weight of the fuel tanks and payload. Higher gee forces means heavier structures. What higher G’s are you referring to? To reach the same altitude in the same amount of times as a rocket, a rail launch assist could match the rocket G for G. But it could do better than a rocket, because it could provide the maximum design G force for the entire length of the rail. In addition, rockets are designed for higher G forces than they experience at take-off, because they have to wait until they pass MaxQ before throttling up to full power. So, your entire argument about G force is irrelevant.


Altitude gain represents less than a twentieth of the energy costs to get to orbit. Most of the kinetic energy required goes into boosting up to orbital speed. That is true. However, a great deal of the energy expended at liftoff, and subsequently within the first minute (for the STS for instance), is lifting the 730,000 kg of fuel in the ET, and the 26,330 kg of the ET tank itself. That is more than 7 times the mass of the shuttle itself (nominal landing mass). Both of these would be reduced by the amount of fuel required to reach 20,000 ft.


The minimal gain for starting at a higher altitude is the reason why we don't launch rockets from the top of mountains. Another Strawman. The object isn’t to start at a higher altitude, but rather to get to that altitude with the same velocity the rocket would under its own power, but without using (or having to carry) the extra fuel.


You'd think it would be a big benefit, but it isn't. In your opinion.

MentalAvenger
2007-Nov-06, 03:22 AM
High isn't a number.It wasn’t intended to be a number. It was intended to express relative cost. Since most aerospace projects (historically) include both large amounts of R&D, and large amounts of government fund gouging, a Mag-Lev Rail Assist should be able to be built relatively much less expensive than traditional aerospace projects.

IsaacKuo
2007-Nov-06, 03:13 PM
Interesting. Your 80 billion dollar estimate magically multiplied by ten again.

No, I boosted the ridiculously cheap 8 million dollar estimate by two orders of magnitude in order to account for the 10x operating speed and the need for vacuum evacuating (without which, it suffers more than 100x the drag and ends up costing more per launch).


In any case, as noted, I wasn’t talking about a 250km Mag_Lev rail like your Strawman was. Starting at sea level, a 20,000 ft mountainside would support a track about 8.6 km (5.35 miles) long.

How much would it cost? I don’t know.

Then you have no idea if it would even save money. As it is, your maglev will cost a lot and it will actually increase the cost per launch.

Consider that it's even cheaper to SLOWLY haul up the components to the top of a mountain using a cheaper roads or rail or cable system. If gaining altitude were actually a big benefit, then we'd already be launching from mountain tops. Do you understand why we aren't?


What higher G’s are you referring to? To reach the same altitude in the same amount of times as a rocket, a rail launch assist could match the rocket G for G. But it could do better than a rocket, because it could provide the maximum design G force for the entire length of the rail.

Well, you COULD try to match the acceleration, but that would mean a funny sort of balancing act. The rocket is stressed to handle acceleration along its centerline. No matter what angle the rocket is at and what the winds are like, the thrust forces will be along the centerline. In order to try and match that with the maglev, you'd have to balance the rocket on its tail, and hope it doesn't tip at all. Despite there being sideways wind which is also stressing the rocket.

But what's the benefit? You "eliminate" the use of fuel during the rocket's most efficient phase? Great. But you're actually increasing the launch costs. For the first 2-3km/s, chemical rocket boosters are EXTREMELY efficient. They convert the chemical fuel energy into payload kinetic energy more efficiently than an internal combustion engine. This is significant, because the maglev is powered by electrical energy. Electrical energy is more expensive than the same amount of energy in chemical fuels, because of conversion losses. Even worse, maglevs aren't very efficient. Compared to wheeled electric trains, maglev wastes energy hovering the vehicle.

So, the maglev actually costs more than the chemical rocket booster per launch, if you only use it for the first 2-3km/s. That's why I specified something which boosts up to 5km/s. Once you get over 3-4km/s is when chemical rockets start getting inefficient, and alternative methods may be less expensive.


In addition, rockets are designed for higher G forces than they experience at take-off, because they have to wait until they pass MaxQ before throttling up to full power. So, your entire argument about G force is irrelevant.

It's relevant because the only way to LOWER launch costs with a maglev is to provide much higher acceleration.


That is true. However, a great deal of the energy expended at liftoff, and subsequently within the first minute (for the STS for instance), is lifting the 730,000 kg of fuel in the ET, and the 26,330 kg of the ET tank itself. That is more than 7 times the mass of the shuttle itself (nominal landing mass). Both of these would be reduced by the amount of fuel required to reach 20,000 ft.

And yet it still costs something to reach 6km altitude via some other means. Reaching it with a chemical rocket is actually one of the more efficient ways to do it. You can reach this altitude at lower costs by going very slowly (to eliminate air resistance losses), but the benefits are just too small to be worth the extra operational costs.


Another Strawman. The object isn’t to start at a higher altitude, but rather to get to that altitude with the same velocity the rocket would under its own power, but without using (or having to carry) the extra fuel.

Do that, and you increase the costs per launch. First stage rocket fuel is cheap and efficient. Electrical energy for a maglev is more expensive and not very efficient.

danscope
2007-Nov-06, 03:33 PM
Actually, it wouldn't have to be maglev, although maglev can be made to give a
pure acceleration dialed in on demand.
But employing a rail with a launch car that has it's own SRB's , up a 4 mile rail
does help the rocket achieve some good acceleration before kicking in it's own
onboard fuel. More payload or higher orbit. A simple rail , although prone to earthquake, could have usefull applications. Certainly less expensive than maglev.
Dan

IsaacKuo
2007-Nov-06, 03:44 PM
But employing a rail with a launch car that has it's own SRB's, up a 4 mile rail does help the rocket achieve some good acceleration before kicking in it's own onboard fuel. More payload or higher orbit. A simple rail , although prone to earthquake, could have usefull applications. Certainly less expensive than maglev.

Or you could do the same thing without the rail, using the launch "car" with SRBs as the first stage of a multi-stage rocket.

crosscountry
2007-Nov-06, 04:19 PM
the moon is a good starting point. I suspect those countries will also want to take part in an international Mars mission, and with existing space programs they will have more leverage to negotiate with NASA and the ESA

Warren Platts
2007-Nov-08, 04:49 PM
There's a new article in the Journal of the British Interplanetary Society entitled "The Feasibility of Linear Motors [a.k.a. maglev] and High-Energy Thrusters for Massive Aerospace Vehicles" by Mark A. Stull that might be relevant and interesting. I don't have access, however.