Who Needs a Space Station? - Using the Moon as a space station

Gennaro · 2003-10-01 06:25:52

First off, this isn?t related to Mars. Mars missions, in my opinon, should be conducted within the framework of the Mars Direct plan, for which the Moon bears no significance.
I?m thinking about the industrial expansion into space and more precisely the infrastructure needed for profitable asteroid prospecting and mining operations directly associated with the economy of Earth.
It?s an idea I?ve been pondering for the last couple of days, although I can say nothing for its originality since I?ve only recently came to attain a detailed interest in these matters. Would be fun though to see how valid it could be. It might include grave misconceptions but then please don?t hesitate to point them out.

To begin with: Two US lunar missions, one in ?94 and the other in ?98, have reported the prevalence of substantial deposits of water ice in permanently shadowed craters on the lunar poles. A long term ESA mission, blasted off a few days ago with a Swedish designed mission pack (yay! :;): ), will more closely detail and confirm these deposits and, which I hope, as a consequence provide information on the level of its extractability.

If the lunar water could be extracted, for example by using a microwave regolith heating technique similar to the one described in The Case for Mars, pp 190-191, it would be able to supply a growing lunar base with water, provided the base is located at one of the poles (the northpole holds larger water deposits and is therefore preferable).
Through simple electrolysis, the same H2O could also provide oxygen (O) and hydrogen (H2) for both life support and chemical rocket propellant (hydrogen/oxygen). Concievably, both the extraction and electrolysis procedures would be powered by a nuclear reactor.
So the scene is amply set for a ?Luna Direct?, wouldn?t you say, with the noteworthy difference that the corresponding ?Ares? lifter would be powered by oxygen/hydrogen instead of methane/oxygen as in the Mars case.

It gets better.

Hydrogen, of course, is the preferred working fluid for nuclear thermal rockets. A NTR could therefore go from the surface of Earth to the surface of the Moon, where it could refuel before returning to Earth. Because the low Delta V needed to escape from the Moon's orbit however, such ships could also elect to go from the Moon to an asteroid mining site instead and presumably return on the same fuel tank with a whole lot of cargo. Now, if we could develop a simple and robust Single Stage to Orbit NTR design, we would get an economical cargo ship to use in the NEO-Moon-Earth system as part of the bargain!

What I propose is this: The design and development of a rugged hydrogen NTR SSTO workhorse, using improved lightweight materials associated with the X-33 (or whatever it was called) and the thrust, power and payload capacity of at least a solid core nuclear reactor spaceship.
The SSTO NTR shall be capable of blasting off from Terra and landing at the northpole lunar base, where it will refuel and load cargo before heading back to Earth. It is not supposed to be able to carry along enough propellant for both legs. Since the SSTO NTR by definition is a vehicle that uses thrust to manage descent (like in 50?s science fiction) and not aerobreaking procedures, the propellant mass requirement and thus the cargo capacity are about the same in both directions. Thus in the case of the Luna ? Earth transit, the ability to refuel is paramount. Alternatively, the basic design could refuel at the Moon and go to pretty much wherever it likes and return on the same fuel tank.
The main advantage of a SSTO is that it?s fully reusable. The vehicle in consideration must be robust and capable of several round trips with a minimum of preparation plus lend itself nicely to mass manufacture.

The Moon base built through a ?Luna Direct? program in this scenario would in other words be not least designed to function as a low Delta V transport node between asteroid mining sites and the terran gravity well, i.e, basically as a space station. Then, what is the advantage of the Moon in this respect to a huge toroidal construct in LEO, GEO or HEEO (high eccentric Earth orbit)?
Simply this:

1) It will provide its own propellant production, while propellant to a space station must be transported there one way or the other.

2) It provides an unlimited stock pile and the base capacity & functions (like SPS construction for example) can be expanded indefinitely without the need to build ?new ground?.

3) Bulk material for simple construction and radiation protection is readily available everywhere by processing of lunar regolith.

Consider the other scenario of building an orbital space station. Huge amounts of material (much of it manufactured on the Moon anyway to keep costs down) must be transported and then assembled in orbit in an engineering effort of gigantic proportions. Much of the lunar made components could be shot into space by a mass driver allright, but that only goes up to a certain size. Big and bulky stuff needs some other way of transportation. The one clear advantage I can see with a space station is the ability to produce a constant 1 g of artificial gravity.
So why not skip the space station stage entirely and use the Moon instead, at least to begin with?
One might argue that Delta V requirements still makes the space station the preferable point of departure for any kind interplanetary propulsion system, but is that really so?
Judging from the following graph, at least with my limited understanding of the subject matter, I can only conclude that the lunar surface is hugely superior to LEO, which still is deep down the gravity well and that by similar comparison, no discernible benefit can be reaped from GEO.

http://www.permanent.com/images/t-gravity-wells.gif

As stated, the Moon base would primarily function as a huge interplanetary transport switch. In a mature state of lunar base development, because of the low gravity, rather economical craft, for example a fleet of comparatively low Isp ?steam ships? (NTR?s using water as a working fluid) that are specialized to access asteroids, could haul bulk freights from Near Earth Objects to the Moon. As water is a common component of asteroids, especially of the carbonateous chondrite class, these ships could refuel at both their point of departure and destination, given the appropriate hardware.
For diving from the Moon into the terran gravity well, a special cargo hauler could be designed, optimized for maximum payload capacity.

Thanks for staying with me through all of the above scribbling. It would be great to read your comments on this concept. Especially from people who have more professional insights into these matters than me. As said originally, I have no clue about the level of originality of this thinking. I?m simply not that experienced with different ideas for space expansion.

dicktice · 2003-10-01 09:54:54

Gennaro: Second off, anything relating to expansion out to space eventually contributes to gaining access to Mars! As far as the ISS is concerned, the reason for supporting and utilizing it to the greatest extent (the list of uses being endless) is . . . because it is there! If it represents "the cart before the horse" in your scenario, so what? It's there, and to allow it to self-destruct would be (nothing personal, understand) the height of stupidity. Besides, it's the unexpected means of Russia/U.S. cooperation in space. I love the rest of your diatribe, especially the asteroid-water accessing part. I would add, merely, that the existence of the ISS provides a ready-made anchor for orbital energy exchange tether operations using crewed and/or robotic exploratory capsules initially to find and examine said hypothetical asteroids. Spaceships encased in ice, for shielding, reaction mass for Solar powered steam jets, air to breath and water to drink, etc. could follow without any recourse to Earthside, except via the ISS as the fallback base, for rehabilitation (centrifuge, companionship, return trips back home) and medical emergencies. See? Great post, since I agree with 99.9% of what you wrote!

Gennaro · 2003-10-02 07:32:15

Dicktice, I wasn't thinking about the ISS at all and my post was no attempt to snipe at it. I was referring to *space stations*. You know, those wheeled giants foretold by von Braun and "2001" in the days of old. Places with pleasant centrifugal g-forces that handle interplanetary flights etc and where you can go lounging in the Corona Bar, waiting for your trip to Mars (the bartender girl wears a silver suit).
In the minds of the general computer gaming public (and you can count me in with that category), the ISS by contrast isn't a space station. It's an orbital laboratory where scientists perform micro gravity experiments and things like that. I didn't build the thing, but I hope that those who did have a lot of fun with it. Besides, I probably agree we should do the most of it now it's there and that hopefully the good it does outweighs the running costs. In principle, U.S-Russian collaboration is always welcome for us caught in the middle and if the ISS can facilitate space flight and be used as a sort of base for expeditions including asteroid prospecting, so much the better!
I'm very delighted you liked my post. I have the utmost respect for your opinions, expertise and judgement.
Speaking about steam ships & solar sails, I feel there?s a peculiar and attractive romanticism to the tone of that.

P.S: You were saying something about the International Space Station and tethers and little capsules. Feel free to fill in further or give a reference.

RobS · 2003-10-02 22:12:57

I think much of Gennarro's posting is close to what will happen in the future if the lunar ice supply is confirmed and proves economically worthwhile to mine (which Robert Dyck has noted on another Forum may not be the case; the ice may be too diluted in regolith).

I would add a few caveats, though:

1. ISS is already NOT in the right orbit to be a jumping off place for trips to the moon or Mars. A station in a more equatorial orbit is needed for that. This was one problem the Soviet moon project had; they could not launch directly into a good orbit to fly to the moon.

2. I am convinced by various arguments that a nuclear thermal rocket will never fly in the Earth's atmosphere because people are too emotional and not rational enough. For the next two or three decades--or more--LEO will be reached by expensive chemical boosters. Possibly a space elevator, tethers, or hypersonic air breathing engines will come along to change that in 20-30 years.

3. Nuclear thermal engines could be used from the moon's surface to low earth orbit if someone can figure out how to aerobrake the nuclear engines safely. Right now, because they tend to be very long (to keep the radiation away from passengers) they are hard to aerobrake.

4. From a total mass point of view, hydrogen-oxygen engines actually are more efficient that nuclear-thermal, because the lunar oxygen, if not used in the engine, has to be thrown away and becomes a pollutant above the lunar surface (where it will spoil the vacuum for lunar astronomy). Water is only 11% hydrogen by weight. Thus twenty tonnes of liquid hydrogen requires the production and electrolysis of 180 tonnes of water, and releases 160 tonnes of oxygen into the lunar environment as a pollutant. I doubt a moon base could use quantities of oxygen that large. You're probably better off hauling the oxygen along and burning it with the hydrogen to push the people and supplies between the Earth and moon (or between earth orbit and Mars). Or you can make a LANTR engine, where you shoot your hydrogen through a nuclear reactor, then add oxygen to it as it exists the ship. The resulting specific impulse is about 700 to 800 (LOX/LH2 is 500; nuclear thermal is 1,000) and you use up the oxygen.

-- RobS

dicktice · 2003-10-03 09:33:08

I keep hoping someone will agree with my premise, of stratovolcano maglev launch ramps, eg. up Kilimanjaro, in Tanzania, which lies on the equator, not to far from the Indian Ocean to the east. Take away the politics, and wouldn't that be the next step to LEO? The tethers for escaping Earth space, and the solar steam-jet inner asteroid prospecting (built in space from dead comet ice) vehicles can begin soon after the first ice asteroid is discovered, all to begin as soon as the ISS becomes operational, eh?

RobS · 2003-10-03 14:45:46

I don't know enough about the technology you are describing, but I am sure "take away the politics" is part of the problem; you can't. Tanzania is a poor country and for a while was a socialist country that nationalized everything. Ecuador may be a better choice; same time zone as the US, mountains as big, and the official currency there is the US dollar.

-- RobS

dicktice · 2003-10-04 10:55:30

Nope, RobS, Tanzania wouldn't be poor for long. It's underdevelopment should be of benefit due to lack of infrastructure to disturb by new railway right-of-way requirements. It could be run by them like the Suez and Panama Canals, for international use at a cost which included operation and maintenance of the launch facility. I looked into Ecuador, and Peru: both with magnificent massifs on the Pacific slopes of the Andes, but way too far from the Atlantic, downrange, and difficult of access from the Pacific coast due to the mountainous intervening "foothills". A Kiliminjaro launch facility would be close both to the Equator and to the Indian ocean (for convenient delivery, retrieval and safety purposes). Africa, and Tanzania in particular, are prime candidates. I'm pleased you seem to accept the stratovolcano launcher principle. Want to pursue this further?

RobS · 2003-10-04 16:56:16

You're right, Tanzania has geographical advantages over Ecuador. But my concern wasn't really poverty; it was political instability. What about Papua New Guinea?

I really am not very interested in pursuing the topic, as I don't know much about it.

-- RobS

dicktice · 2003-10-07 17:10:31

Nor am I, the politics properly motivated will take care of itself--but the hardware--that's where my interest lies: What maglev re-useability, what launched fuel-tank in space adaptability, what general international space agencies' useability, what multiple space assembly growth potential, what rapid launch capability, what orbital planes of choice possibility! What's not to be interested in? (Thinks: Hope somebody else picks up on this topic; it needs a good brainstorming, is what it needs!)

GCNRevenger · 2003-10-14 19:37:03

Okay I see a feeew problems that are somthing of an issue with a NTR SSTO vehicle (which are also on the NuclearSpace message board)...:

A nuclear reactor when its fueled for the first time with fresh Uranium 235 isn't very radioactive, but when you switch the thing on in order to take off from Earth or a handy nearby Lunar launchpad, its going to put off a -silly- large amount of radiation without shielding of unreasonable mass. Plus, you would need a very large and heavy reactor to produce enough raw thrust to get off the ground; the original NERVA engines topped out at 250Klb of thrust and as far as launching go would be used as a Saturn-V UPPER stage, after you have momentum.

It simply isn't practical to use the engine near a Moon base or in Earth's lower atmosphere. Further, when a reactor is turned off it will keep on radiating for a while (read: at least a year) due to leftover extremely radioactive fission fragments, so you really can't bring it back to Earth's surface at all or near a Lunar base easily. It will be enough trouble to dock acent/decent vehicles or space stations to a nuclear transfer stage to avoid frying an unwary crew in orbit. Space reactors belong only on orbital transfer vehicles or uninhabitated surfaces unless they are heavily (eg burried, concrete/HDPE/lead, large water shield, thick steel etc) shielded.

On to the Lunar base concept... since it is so much trouble to launch masses into LEO as it is, the hefty payload penalty to get to the Moon would make a sizeable base difficult even with a 100-150 ton LEO chemical launchers which we are stuck with in the near term, so at the moment a LEO station makes more sense. In the near-distant future, after Project Prometheous has given us a nuclear-electric ion engine or a reuseable NTR engine, then sending up an initial base on heavy chemical launchers to get to the Moon becomes practical. When/if the Moon's polar ice starts yeilding signifigant amounts of water, then the REAL Moon city can begin... Lunar LH2/LO2 powering reuseable acent/decent lifters to refuel a waiting nuclear-powerd transfer stage... and anywhere we want to go without having to bother with 1G gravity or an atmosphere.

Of course, getting to Mars if we have a NTR engine and Moon Base technology would be easier than making a big enough Lunar base to mine enough water to fuel sizeable rockets...

Oh, one last note, you can't pollute the Moon with any pitiful tiny amount of oxygen we could waste, most of it would probobly just waft away into space due to the low gravity (hence the Moon being airless), but if you WERE really concerned about it, you could just mix it with Lunar metals and trap it on the ground as a solid oxide by heating.

Gennaro · 2003-10-18 20:02:18

A nuclear reactor when its fueled for the first time with fresh Uranium 235 isn't very radioactive, but when you switch the thing on in order to take off from Earth or a handy nearby Lunar launchpad, its going to put off a -silly- large amount of radiation without shielding of unreasonable mass.

You sure about this? Naturally, I reckoned that design thinking for NERVA type NTR's already included appropriate reactor shielding. If ground launches aren't feasible even with solid core NTR's, however, I really see no compelling reason to design such vehicles. The main purpose of nuclear propulsion according to me is exactly that it seemed to provide means for repeated Earth - interplanetary round trip transits. I don't care about Isp for speed, but for lifting capacity.
Oh well...

Gennaro · 2003-10-31 02:41:12

Okay, so a fission NTR isn?t feasible for ground launch and landing because of radiation from spent reactor fuel. Since I earlier took the appropriate shielding for granted in this regard (the hazard was never mentioned anywhere while it normally would be the first thing to think about when designing a SSTO), I might as well ask about another unclarified issue. What about emissions from the propellant exhaust? After all, the working fluid has run through the reactor.
I?ve tried to get some information on this ever since Nuclear Space frequented these boards, but nowhere have I seen an answer clearly spelled out. Obviously, I previously feared it also was a question too dumb to ask.

Gennaro · 2003-10-31 06:35:20

Think it's a good idea.

Only two considerations:

1) First you'll need a space elevator. Zubrin (Entering Space (1999), p.99) says it's not possible building one because the cumulative g-load put on the tether the further down you go from GEO (supporting not only the jump off point but the cable itself). The site in the link claims it is, with new materials, so there seem either to be a conflict of opinion or important developments have occured. I'm just general public so I wouldn't know.

2) Moving mass up is not the only challenge, even more so is coming down again, because as you see in my post, I'm primarily concerned with bulk hauls of asteroidal ore. If we can't devise an economical and practical transport system to make the goods available for customers on Earth for a competitive price, we might as well forget about the whole space resource utilization business. No matter how precious, those natural resources are totally worthless if we can't get them down here.
What it boils down to is not least economics of scale and the ability to send down a few astronauts just isn't good enough.

The elevator in the link has a capacity of 5 tons daily. Will it pay off considered the investment and service requirements? Expanding the capacity is inelastic. To do so you would have to build a whole new elevator. Huge investment.
But then what about the facilities required on top of the beanstalk? You'll need a place to dock space ships, transfer cargo to the elevator, cargo and fuel storage etc. The weight of that will be a lot more than 5 tons.

Finally, you must get the fuel in place. (A major benefit in my original post was refuelling propellant on the Moon, provided the polar water is available in concentrated form, an issue that actually seems far from settled).

Gennaro · 2003-11-01 07:45:50

I've had time to browse through the webpage a little further now and I'm very impressed with it.

The initial cost for building the 5000 kg/day version is estimated to about 10 billion $ with an operating cost of 156 million $/year. Naturally, as you point out, successive elevators will be a lot cheaper, but that goes for for additional units in a fleet of advanced SSTO's as well. So that's only trivial.
The proposed larger version can handle 22 tons to GEO daily. Me like.

For comparison a new Titan use-and-forget booster which also can lift somewhat above 5000 kg (11 500 pounds) to GEO, costs $300 million (but could be had for 30 million according to Zubrin if NASA (or ESA) didn't adhere to private contractors within the current system). A Boeing 747 costs $100 million.
Have no idea what an individual nuclear SSTO would cost but with a rational financial setup, for example wholly government developed and built by contracting individuals rather than private, max profit space company dinosaurs, I wouldn't be surprised if an individual unit down the series would be three times as expensive as Zubrin's chemical Titan, or about 100 million $.
That's about the running costs for the elevator for an entire year!

What's really impressive are launch costs per kilogram to GEO compared with present day systems. $600 for the first elevator with prospects down to as low as $10! One way to GEO today costs as staggering $80 000/kg!

Other than individual unit cost for a serially produced advanced SSTO, system development, infrastructure, ground control etc is not included, not to mention the financing of Moon structures, which would be massive. (The basis of the Moon base in my original idea would consist in a "Luna Direct" plan and hence not immedeately related to the operation of gravity transcending vehicles, yet expanded as need be for industrial and transport purposes.)

What I personally find really appealing is that the elevators, perhaps a small cluster of them, make construction of a real "small town" sized toroid space station using Earth materials an actual possibility, as well as supplying it with space ship fuel and provisions.
The dream comes true.

Well, I guess one can say you have just about convinced me.

Indeed, it's far from settled. On the other hand, how much is much? I thought that when they announced water on the Moon, they meant something like a few grams in a square km... or something similar. Why do i have that impression stuck in my head?

This is what Zubrin says about it in Entering Space, p.94:

Lunar Prospector was launched in January 1998. By March, the mission's principal investigator, Dr Alan Binder, was ready to announce the results. According to Binder and his team, Lunar Prospector's neutron spectrometer had detected water, in concentrations of about 0.5 percent in both the Moon's polar regions. The actual neutron spectrometer measurement indicated hydrogen in concentrations of about 0.05 percent (500 ppm). Binder and his team inferred that the detected hydrogen was in the form of water (which weighs nine times as much as the hydrogen it contains), an assumption that is supported by most, though not all, of the planetary space community.
Soil containing 0.5 percent water is a lot wetter than any previously known to exist on the Moon, but it's still drier than the Sahara, Martian desert dirt, or dry concrete for that matter. However, Binder believes that the water he detected might not be in the form of 0.5 percent dilute permafrost spread over the entire pole, but instead might exist as small crater ponds of pure or nearly pure ice scattered across the polar region. Such a result would be more consistent with the Clementine radar findings (which hardly would have noticed dilute permafrost). The 0.5 percent ice signal would then result from the fact that these frozen water concentrations cover about 0.5 percent of the polar area under study. If that were the case, it would make the water detected by Lunar Prospector a much more readily exploitable source.

Incidentally, since I hadn't started reading the book when I wrote the first post, Zubrin also has the following to say about the potential uses for the Moon (pp.95-96):

But if Lunar water is availabe, then both oxygen and hydrogen can be provided, and the chemical process required to produce them becomes much simpler (only electrolysis is required) as well.
So the idea of the Moon as a refueling station is interesting. It has it's possibilities, but also it's limitations. Using lunar propellants as a means of refueling Moon base spacecraft for their return to Earth or for hopping around the Moon makes perfect sense. Surprisingly, however, using a Moon base to refuel spacecraft on their way from Earth to Mars offers no benefits at all. ---

Of course, that comes as no surprise to people around here...

--- However, if the destination chosen is well beyond Mars, the balance of benefits shifts. For example, the delta V to go from LEO to Ceres, a planetoid in the heart of the asteroid belt, is 9.6 km/s, which is greater that that required to go to either lunar orbit or the lunar surface. So, if lunar propellant could be made available in these locations cheaply enough (compared to simply lifting the required 9.6 km/s worth of propellant from Earth to LEO), Moon-based refueling could be advantageous. As the destination chosen is moved farther out, the required mission delta V's grow, and so do the potentail benefits of lunar refueling. Of course, it would never pay to set up a lunar refueling station for the benefit of one or two outer solar system missions; the basic infrastructure would cost too much. But if there were regular interplanetary traffic, say to support mining operations in the main asteroid belt (see Chapter 7), a lunar refueling station might find itself with a vital supporting role.

So far Zubrin.

Concievably, the Moon to Main Belt ships could of course be made for maximum Isp while still carrying break even amounts of cargo, while the Luna-Earth SSTO's that I proposed would be optimized for maximum thrust and heavy cargo payloads.

Anyway, if there is indeed water on the Moon, will we be so stupid to decompose it to H2 and O2 and use it as propellant, instead of keeping it for future colonies ?!

- No not stupid, practical. There was nothing in my scheme implying that the use of the Moon as a water extracting refueling station would have to be a permanent feature in the long run. Yet, to construct a space station you would probably have to build a Moon base anyway to supply relatively cheap construction material, not least for radiation shielding.
Naturally, one should plan not to exhaust polar water supplies in waiting for demand to rise on He3 exports, in which the Moon would find itself with largely a different role.

However, with the space elevator I admit that the entire outlook on these challenges changes radically and profoundly.

Gennaro · 2003-11-01 08:31:59

I've had time to browse through the webpage a little further now and I'm very impressed with it.

The initial cost for building the 5000 kg/day version is estimated to about 10 billion $ with an operating cost of 156 million $/year. Naturally, as you point out, successive elevators will be a lot cheaper, but that goes for for additional units in a fleet of advanced SSTO's as well. So that's only trivial.
The proposed larger version can handle 22 tons to GEO daily. Me like.

For comparison a new Titan use-and-forget booster, with a similar lift capacity somewhat above 5 000 kg to GEO (11 500 pounds) costs $300 million (but could be had for 30 million according to Zubrin if NASA (or ESA) didn't adhere to private contractors within the current system). A Boeing 747 costs 100 million $.
Have no idea what an individual nuclear SSTO would cost but with a rational financial setup, for example wholly government developed and built by contracting individuals rather than private, max profit space company dinosaurs, I wouldn't be surprised if an individual unit down the series would be three times as expensive as Zubrin's chemical Titan, or about 100 million $.
That's about the running costs for the elevator for an entire year!

What's really impressive are launch costs per kilogram to GEO compared with present day systems. $600 for the first elevator with prospects down to as low as $10! One way to GEO today costs as staggering $80 000/kg!

Other than individual unit cost for a serially produced advanced SSTO, system development, infrastructure, ground control etc is not included, not to mention the financing of Moon structures, which would be massive. (The basis of the Moon base in my original idea would consist in a "Luna Direct" plan and hence not immedeately related to the operation of gravity transcending vehicles, yet expanded as need be for industrial and transport purposes.)

What I personally find really appealing is that the elevators, perhaps a small cluster of them, make construction of a real "small town" sized toroid space station using Earth materials an actual possibility, as well as supplying it with space ship fuel and provisions.
The dream comes true.

Well, I guess one can say you have just about convinced me.

Indeed, it's far from settled. On the other hand, how much is much? I thought that when they announced water on the Moon, they meant something like a few grams in a square km... or something similar. Why do i have that impression stuck in my head?

This is what Zubrin says about it in Entering Space, p.94:

Lunar Prospector was launched in January 1998. By March, the mission's principal investigator, Dr Alan Binder, was ready to announce the results. According to Binder and his team, Lunar Prospector's neutron spectrometer had detected water, in concentrations of about 0.5 percent in both the Moon's polar regions. The actual neutron spectrometer measurement indicated hydrogen in concentrations of about 0.05 percent (500 ppm). Binder and his team inferred that the detected hydrogen was in the form of water (which weighs nine times as much as the hydrogen it contains), an assumption that is supported by most, though not all, of the planetary space community.
Soil containing 0.5 percent water is a lot wetter than any previously known to exist on the Moon, but it's still drier than the Sahara, Martian desert dirt, or dry concrete for that matter. However, Binder believes that the water he detected might not be in the form of 0.5 percent dilute permafrost spread over the entire pole, but instead might exist as small crater ponds of pure or nearly pure ice scattered across the polar region. Such a result would be more consistent with the Clementine radar findings (which hardly would have noticed dilute permafrost). The 0.5 percent ice signal would then result from the fact that these frozen water concentrations cover about 0.5 percent of the polar area under study. If that were the case, it would make the water detected by Lunar Prospector a much more readily exploitable source.

Incidentally, since I hadn't started reading the book when I wrote the first post, Zubrin also has the following to say about the potential uses for the Moon (pp.95-96):

But if Lunar water is availabe, then both oxygen and hydrogen can be provided, and the chemical process required to produce them becomes much simpler (only electrolysis is required) as well.
So the idea of the Moon as a refueling station is interesting. It has it's possibilities, but also it's limitations. Using lunar propellants as a means of refueling Moon base spacecraft for their return to Earth or for hopping around the Moon makes perfect sense. Surprisingly, however, using a Moon base to refuel spacecraft on their way from Earth to Mars offers no benefits at all. ---

Of course, that comes as no surprise to people around here...

--- However, if the destination chosen is well beyond Mars, the balance of benefits shifts. For example, the delta V to go from LEO to Ceres, a planetoid in the heart of the asteroid belt, is 9.6 km/s, which is greater that that required to go to either lunar orbit or the lunar surface. So, if lunar propellant could be made available in these locations cheaply enough (compared to simply lifting the required 9.6 km/s worth of propellant from Earth to LEO), Moon-based refueling could be advantageous. As the destination chosen is moved farther out, the required mission delta V's grow, and so do the potentail benefits of lunar refueling. Of course, it would never pay to set up a lunar refueling station for the benefit of one or two outer solar system missions; the basic infrastructure would cost too much. But if there were regular interplanetary traffic, say to support mining operations in the main asteroid belt (see Chapter 7), a lunar refueling station might find itself with a vital supporting role.

So far Zubrin.

Concievably, the Moon to Main Belt ships could of course be made for maximum Isp while still carrying break even amounts of cargo, while the Luna-Earth SSTO's that I proposed would be optimized for maximum thrust and heavy cargo payloads.

Anyway, if there is indeed water on the Moon, will we be so stupid to decompose it to H2 and O2 and use it as propellant, instead of keeping it for future colonies ?!

- No not stupid, practical. There was nothing in my scheme implying that the use of the Moon as a refueling station would have to be a permanent feature in the long run. Yet, to construct a space station you would probably have to build a Moon base anyway to supply relatively cheap construction material, not least for radiation shielding.
Naturally, one should plan not to exhaust polar water supplies in waiting for demand to rise on He3 exports.

However, with the space elevator I admit that the entire outlook on these challenges changes radically and profoundly.

RobS · 2003-11-01 12:08:35

Added to force a new page.

GCNRevenger · 2003-11-02 09:26:29

The elevator idea would be nice for hauling bulk cargo up like rocket fuel and satellites, but I have some reservations about how reliable it will be with all the space junk floating around or any small imperfections in the CNT composit cable that might lead to somthing... catastrophic.

It will be entirely useless for human travel without a much larger version, since anybody sent up the elevator would get too big a dose of radiation without carrying a massive shield. Apollo was okay because it only spent an hour or two in the radiation belt around Earth, spending 24-48 even 72 times as long in the region gives you 24-48 even 72 times the dose.

I also have my doubts that it would be useful in the near term over an Energia/SDV HLLV paired with semi-reuseable EELVs with flyback boosters, simply because it would not be easy to haul up large objects. The ISS debacle compared with Skylab should have taught us all the lesson quite clearly that building large things in orbit in little pieces is insane.

Finally, about asteroid mining... asteroid mining is a completly crazy idea. I don't think it will ever be able to compete with Earth-based mining operations, simply because its too hard to get the stuff back to Earth in bulk. Only five tons a day from an elevator and a few dozen billion dollars for the mining operation, and the millions/billions a year used to push the stuff back to Earth? Not unless Greenpeace gets the UN to ban mineral mining or somthing.

The only hope for mining minerals from asteroids is to bring the asteroid to a large "heavy" space elevator station in GEO, and send down alot more than five tons a day... even then, it will be very hard to justify the massive cost of pushing an asteroid into Earth orbit! ...No. If we want humanity to exploit the wealth of the solar system, we have to bring humanity to it, not it to Earth. After all, people don't weigh that much...

Adrian · 2003-11-05 12:47:07

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#1 2003-10-01 06:25:52

Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

#4 2003-10-02 22:12:57

Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

#12 2003-10-31 02:41:12

Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

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Re: Who Needs a Space Station? - Using the Moon as a space station

#17 2003-11-02 09:26:29

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#18 2003-11-05 12:47:07

Re: Who Needs a Space Station? - Using the Moon as a space station

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