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View Full Version : Back to the moon, for dummies



somerandomguy
2003-Nov-06, 11:10 PM
Hi again.

A month or so ago, I posted here looking for help with a newspaper package about the South Pole. Everyone was more than helpful, of course, and reading the board (chronic lurker that I am) has given me more ideas for packages.

The next project I'm taking on regards missions to the moon. It's pegged to the surge in China's space program, as well as the possibility of an announcement of a resumption in manned lunar missions in that Dec. 17th speech.

The page will have a heavy focus on America's lunar history -- what the Apollo program was, when its goals were achieved, and what it meant. Then my goal is to compare those Apollo missions to what a modern-day moon mission would look like in terms of hardware used, science capability, mission duration, and factors like that. I know that very little has been decided at the official level; I'm looking for reliable extra-governmental sources that can speculate with some accuracy as to what a moon mission might look like.

Does anyone know if a contractor or NASA engineering group has come up with a publicly-available proposal for a lunar transport vehicle? Or do you know what might be the key "upgrades" added to the old Apollo hardware as a result of technological progress? Can anyone tell me what the scientific or exploratory goals of new missions might be, or better yet, direct me to an official briefing or major publication on the topic?

Any help you folks can offer will be greatly appreciated and will, of course, go toward the goal of keeping the mass media well-stocked with "good astronomy."

Thanks!

Glom
2003-Nov-07, 01:52 PM
No-one, apart from the Chinese potentially, although they don't say much, have been developing any manned Lunar vehicle, let alone a commercially viable one.

The Apollo hardware would only be of limited help to us right now. After Nixon pulled the curtain of the programme, most of the detailed work was junked, as it would otherwise take up a huge amount of space while serving no purpose other than sentimental value.

We'd need to redevelop the ultra-heavy lift boosters like the Saturn series or the Nova series. There is no escaping that the politicians will have to realise the nuclear option will be required sooner or later if they have more than crash program plans.

The question is, how would a mission be done? For Apollo, three possibilities were explored:

Direct ascent
This involved the use of the mecha-ultra-heavy lift booster, the Nova. IT would launch an all in one spacecraft that was capable of boosting directly to moon, landing and returning by itself.
It was rejected because the Nova wouldn't be ready in time for Kennedy's deadline. If Bush is series about the nuclear (or nukyular as he would say) option, then this becomes more viable for any plans he might have.

Earth orbit rendezvous
With the Nova out of the question, the next most powerful booster was considered, the Saturn. The Saturn could launch the all in one spacecraft in two components that would rendezvous in LEO, assemble and then continue to the moon, land and return.
Problem? A logistical nightmare. Plus it would be expensive. If the American space program had succeeded in actually developing space infrastructure, this plan could have been useful.

Lunar orbit rendezvous
This plan split up the spacecraft into an orbital module and a lander. Because the lander was only going to be used for landing, it could be made extremely light and the end result was that the two spacecraft combined would be lighter than the all in one spacecraft. It could be launched on a single Saturn V. The lander would land and rendezvous with the orbital module in Lunar oribt.
Problem? It was insane. LOR was deemed far too dangerous. But, the deadline approached so they went it. This plan would probably be considered most because it has been done before.

daver
2003-Nov-07, 08:38 PM
I don't think it's likely that the US will engage in another lunar mission in the forseeable future, but I suppose it is possible.

I suppose you could play this two ways--either assuming the shuttle continues to fly and dividing the pieces into shuttle-sized segments, or assuming the US builds a new booster from the ground up. If it is to be done by shuttle flights, the mission will probably take the form of an Earth Orbit Rendezvous. If it is to be done by a spanking new booster, it could either be EOR or LOR. Perhaps the shuttle could be used to carry up the core of the craft (fueled would be best, although that's not going to go over well) and expendables to carry up the fuel tanks.

It looks to me as if it's about 10 km/sec delta V from LEO to the surface of the moon and back to earth intercept. At an Isp of 311 (Apollo LM) that's a mass ratio of about 25. If you use higher energy fuels (LO2/methyl hydrazine has been proposed for a different use) you might be able to get that down to about 13. I don't think LH2 would work too well--the fuel would likely be stored on-orbit for perhaps a year. With a high energy fuel, your reentry capsule, landing gear, exploration gear, main engines, and lunar ascent fuel could be packed into one shuttle load.

I'd envision the lunar vehicle as consisting of a reentry capsule (a glorified Apollo capsule); a vehicle core consisting of perhaps 15 tons of fuel, support hardware and engine as well as RCS and whatnot; a lunar landing base consisting of landing legs and lunar exploration supplies; and a bunch of jettisonable fuel tanks. The fuel tanks would be launched on expendables; after they'd been maneuvered into position the combined reentry capsule, vehicle core and landing base toegther with the crew would be launched on a shuttle. The fuel tanks would be designed to be plugged together with a minimum of fuss (presumably earlier shuttle flights, with fuel tanks filled with water or some other benign substance, would test the assembly procedure). Shuttle moves out of the way, vessel blasts off for the moon (shedding tanks as it exhausts them), direct descent to the lunar surface. Poke around a bit, then take off, leaving the landing base behind (a la the Apollo LM). Direct ascent into earth intercept orbit. Ditch the vehicle core, land in the reentry capsule.

This configuration could be modified to be a cargo lander--the reentry capsule and ascent fuel could be replaced by cargo, although it might perhaps be better to launch those directly from earth (if you can put 10 tons into GTO, you ought to be able to land 5 on the moon).

This requires an Apollo-style reentry capsule, and a reliable, restartable, throttleable engine. It requires earth-orbit assembly of perhaps dozens of fuel tanks. It requires unmanned orbital rendezvous techniques. It requires development of modular fuel systems. It could be done using a mix of expendable and shuttle launches, although it could be done a lot quicker if we had a man-rated super-heavy launcher. I figure roughly ten years, given a minimum of micromanagement.

somerandomguy
2003-Nov-07, 09:31 PM
You guys are a huge help. Thanks so much!! :D

It seems the wisest thing to do would be to focus on the history, and then whatever future/present elements I use will be pretty speculative. Glom's information, especially, will be helpful.

Now it's off to the library to fill in the gaps! If anyone has further thoughts, or suggestions as to links or specific books to read, please do post them. I appreciate all the help!

crazy4space
2003-Nov-07, 09:48 PM
[
quote="somerandomguy"]You guys are a huge help. Thanks so much!! :D

It seems the wisest thing to do would be to focus on the history, and then whatever future/present elements I use will be pretty speculative. Glom's information, especially, will be helpful.

Now it's off to the library to fill in the gaps! If anyone has further thoughts, or suggestions as to links or specific books to read, please do post them. I appreciate all the help![/quote]

You might want to talk to JayUtah before you write this. His websiite is Clauvis Moon Base or he can be found here on the BA site.

daver
2003-Nov-07, 10:21 PM
Now it's off to the library to fill in the gaps! If anyone has further thoughts, or suggestions as to links or specific books to read, please do post them. I appreciate all the help!
This site has some book recommendations: http://my.execpc.com/~keithp/alib/alibap.htm

I don't know anything about this site, i just googled for web sites with Chariots for Apollo in them.

Peter B
2003-Nov-08, 07:01 AM
The page will have a heavy focus on America's lunar history -- what the Apollo program was, when its goals were achieved, and what it meant. Then my goal is to compare those Apollo missions to what a modern-day moon mission would look like in terms of hardware used, science capability, mission duration, and factors like that. I know that very little has been decided at the official level; I'm looking for reliable extra-governmental sources that can speculate with some accuracy as to what a moon mission might look like.

Does anyone know if a contractor or NASA engineering group has come up with a publicly-available proposal for a lunar transport vehicle? Or do you know what might be the key "upgrades" added to the old Apollo hardware as a result of technological progress? Can anyone tell me what the scientific or exploratory goals of new missions might be, or better yet, direct me to an official briefing or major publication on the topic?

I think that the process used to get to the Moon will depend largely on what the purpose of the mission(s) will be.

If we're looking at an Apollo 2nd generation, then perhaps we look at simply resurrecting all of the Apollo and Saturn hardware, and redesigning it to take advantage of new technology, software and materials. That allows two approaches. With a slight increase in available payload, we either include more safeguards to make the missions safer and less prone to aborts. Or we proceed with the same sort of safety margins that Apollo had back in the 60s and 70s, and try to squeeze more out of the missions.

If we're looking at a longer term set of missions - like the ISS on the Moon, then perhaps we go for a series of unmanned launches using expendable rockets to place material on the Moon - habitats, supplies, rovers and return vehicles - and send the astronauts via separate missions with the minimum resources necessary to allow them to assemble the material already on the Moon.

The big question is what sort of safety margins are expected. As (I think) JayUtah has pointed out, virtually every Apollo mission had some sort of serious problem which could've led to an abort had it not been worked around. By comparison, the Space Shuttle has experienced two catastrophic failures and one abort to orbit in about 110 missions. What sort of survival rate would you expect, and what sort of success rate would you expect? The answers to these questions would have a major effect on the cost of the missions.

However, another question which would affect the cost would be the timescale of the project. The longer and larger the project, the cheaper the hardware becomes per unit (generally).

eburacum45
2003-Nov-08, 08:51 AM
The most remarkable advances must be in electronic systems; the Apollo computers were like pocket calculators; if an upgraded Apollo were built, the control and navigation would be far superior.

As no great advances in propulsion systems have occurred an upgraded Apollo program could end up producing similar, if not identical designs, apart from the on-board electronics, IMO.

Peter B
2003-Nov-08, 08:59 AM
The most remarkable advances must be in electronic systems; the Apollo computers were like pocket calculators; if an upgraded Apollo were built, the control and navigation would be far superior.

True. But the computing power could also be used to control a lot of other things (environmental systems for example) with much greater precision.


As no great advances in propulsion systems have occurred an upgraded Apollo program could end up producing similar, if not identical designs, apart from the on-board electronics, IMO.

I agree with the comment about propulsion systems. Except that improved computer power could allow more efficient control of engines and fuel consumption.

But another area of weight saving would be in new composite materials which could be stronger and lighter. The key here is that significant weight savings in the first couple of stages could allow much larger payloads to be launched compared with the old Saturn Vs.

JayUtah
2003-Nov-24, 04:26 AM
Increased onboard computing power doesn't necessarily give you a whole lot in terms of greater capacity. If you're going to put people on the spacecraft, teach them to fly the spacecraft and reap the benefits of a human pilot. The advantage to better computer technology is that the computer will be smaller and lighter. We don't need it to play MP3s.

Okay, I'm not a good policy expert. People tell me what they want, and I build it for them. The only company I know of with designs for going back to the moon is TransOrbital, and they're just now preparing their first unmanned spacecraft.

But the cost of manned lunar exploration is still high enough that we can probably only expect a government to undertake it.

If we want to send people back to the moon, there are certain things we'll probably keep. Lunar orbit rendezvous, for one. We know that works. If we want to try it some other way we'll have to develop the procedure. That means a separate "transit" spacecraft and "lander" spacecraft. You want both to be manned so that there are two pilots available for the rendezvous. That means two habitable volumes (as opposed to the lunar orbiter being just a propulsion and consumables unit).

You need some way of getting that mess on its way to the moon. The best way is staging with an expendable propulsion unit.

You need some way of braking the mess on its way back from the moon. We know how to do aerobraking for that, so we can do it again. The alternative is an engine burn, requiring quite a lot of fuel.

Now we need some way to get it all up into orbit. You can stack it all on one big booster, or stack pieces of it on little boosters and try to put it all together in orbit. We don't have a really big man-rated booster except for the space shuttle (which has temporarily lost its man rating). But assembling in earth-orbit rendezvous fashion requires the complexity of rendezvous and docking, plus two or more launches. Complexity means money.

In case you haven't figured it out, we're basically re-inventing Apollo. For being a "crash" project, it was designed correctly.

How would we improve on it? Extended-stay capabilities. Unfortunately that means a different strategy for radiation protection. The longer you stay, the greater the risk for solar activity. But the initial hardware will probably bear a striking resemblance to the original Apollo hardware. We know it works in principle. Updated electronics, of course. Updated materials. But form follows function, and as long as the function remains the same, the form will stay largely the same.