The Moon Society Forum

Lunan engineers will have some unique challenges. They will also have some unique advantages.

1) Artist's renditions of stuff on the Moon are deceptions. Their stuff is all tubular, curved, domed and streamlined. That's too complicated to make. From mining shovel buckets to vehicle cabins to RR cars and habitat modules all we need are rolled and cut flat plates welded up into "boxy" shapes. Let me qualify this statement a bit. The reason all those paintings show us cylindrical modules is because that stuff has to be launched on a rocket. The engineers at the Moon Society St. Louis chapter have proposed welding up simple iron "boxes" with reinforcing webs on the Moon. They have even done computer analyses of the stresses and determined that these "mobile home" like modules would hold up to 5 psi with high safety margins. As for concrete modules, those might be cylindrical with domed ends and very thick walls, possibly reinforced with rebar or glass fibers, for improved strength since pressure wants to balloon up into a spherical shape. Perhaps we might even be able to make concrete spheres. Concrete could be a very useful material. We'd probably need to let it dry in large upported inflatabels to recover the water vapor. Buried underground concrete will not endure thermal cycling that could lead to cracking. Those boxy iron modules might be good for working with machine tools that might set up vibrations in concrete modules that could lead to cracking. Whatever we do, combined approaches are probably the best strategy.

2) NASA stuff is all very complex, microminiaturized, lightened, exotic and expensive so they can rocket it up there. Stuff we will make on the Moon could be much simpler, thus cheaper.

3) The lunar mining engineer's job is simplified because 99% of the mining will be strip mining. We might blast and tunnel a little bit into central crater peaks if there's anything of value from the lunar deep strata in there. Drilling for volcanic gas-who knows? And there's no ground water to deal with. Less gravity=less cave in danger.

4) The lunar architect and civil engineer's jobs are simplified because there is no wind and no ground water to contend with and less gravity. These are the guys who will use cast basalt (bricks, pipes, tiles), glass, glax, concrete, cement board, drywall and loose regolith for much of their work, as well as iron plates.

5) The lunar electrical engineer must learn to do everything with aluminum and calcium wire; and upported superconducting wire. Solar panels produce DC so we will use a lot of DC electrical stuff. Superconductors can transmit DC as easily as AC, so we won't need transformers and substations. Yes, we could transmit 110V current for thousands of miles over the Moon with SC wires.

6) Furniture, housewares; all stone, metal and glass. No wood=no carpenters, but we might saw and nail together aereated autoclaved concrete stuff.

7) Chemical engineers won't do much organic chemistry outside of small laboratory workshops for small batches of plastic and silicones.

8) The metallurgy guys will have to figure out how to make smelting furnaces and other stuff out of local materials for producing materials from Moon dust.

9) welding w/o the hassles of oxygen or in the case of titanium burning in nitrogen as well as O2 will make it possible to do welding, std. electric arc and tungsten electrode without shield gases. in the out-vac.

10) rolling flat plates of metal and welding up all sorts of "boxy" things will be rather straightforward, but i've heard it argued that if you could upport a rolling mill for flattening out hot soft ingots of metal into flat plates why not one for rolling curved plates? Well, I'll let the discussion simmer over this one

11) assembling parts made by 3D sintering. some assemly could be done by humans and some by multi-purpose programmable robot arms

12) conventional casting and machining operations-some done by humans and some by automation. Work might best be done in pressurized inert gas filled chambers so that molten metals don't evaporate away and the atmopshere in the chamber helps cool equipment

13) making solar panels, batteries and/or fuel cell systems, electric motors of various sizes for everything from ventiliation fans to O2 compressors to water/sewage pumps to vehicle propulsion to heavy equipment power,
mechanical arrangements using pulleys, augers, etc. to replace hydraulic and pneumatic devices, and automating all the above with robotics

One question that your post brings up for me (and, if you prefer, I'll split this off as its own topic): Breathing gas mixtures. If my cursory check is accurate, Apollo used straight oxygen at 5 psia. Since research showed that pure oxygen was not desirable from a physiological standpoint on an extended mission, Skylab used 80% oxygen/20% nitrogen at 5 psia. However, the shuttle uses sea-level 80% nitrogen/20% oxygen at 14.7 psia. This is why shuttle astronauts must spend several hours in the airlock breathing straight oxygen, purging the nitrogen from their system to prevent an attack of the bends when they make an EVA (spacesuits use straight oxygen at ~3.5 psia).

There is really no reason why we need to tie ourselves to Earth's sea level atmosphere. For my own fictional moon colony, I'm proposing a three-tiered gas mixture. For "high pressure" zones the mix would be 75% nitrogen and 25% oxygen at 12.3 psia. In "low pressure" zones the mix would be 50% oxygen and 50% nitrogen at 6.2 psia. For outside work in spacesuits, again it would be pure oxygen at 3.5 psia. The objective being that workers could pass from a "high pressure" area to a "low pressure" area without risking an attack of the bends, and likewise when going from a "low pressure" area to Outside. If someone wanted to transition from a high pressure area to a spacesuit, he would first spend a few hours in a low pressure area to flush some of the excess nitrogen from his system.

Comments on this?

I was thinking 5 psi with 3 psi O2 and 2 psi N2

Your idea seems very plausible to me

Makes me think, somewhere I read a piece by A.C. Clarke where he describes concentric wheel space stations with different levels for different G intensities so that space travelers returning from long missions could stay at the say 0.2 G level for a while then move up to higher and higher G levels to reaclimatize themselves to Earth gravity before returning.

To build anything on the Moon we will need materials, so I've given a lot of thought to that. Rather than go into the details of metal and non-metal production, I want to ask what if anything does anybody know about mass spectrometers. Years ago I brought up the idea of a giant mass spec to separate elements from regolith and someone shot the idea down by pointing out that the mass spec used by the Manhattan Project was 3 stories tall, used all the power of the TVA at night, and refined out just about 20 pounds of Plutonium. It seems as if such a dievice would be impractical. I read later that silver from the US mint was used for the machine's coils.

What if we used superconducting wire for the coils? Could this shrink the size and mass of the magnet and reduce power demands to an acceptible level?

Such a device is one of the "Holy Grails" of space industry. It would not require upported chemicals or elements rare on the Moon and it might get elements that can't be gotten any other way. I've also thought that if such a machine is very expenisve to build and operate, perhaps it could turn a profit by extracting PGMs which are of great value.

The Oak Ridge plant was not a "mass spectrometer"; it was an isotope separation facility which used calutrons (a close relative of the cyclotron).to separate U-235 from U-238—a much more difficult challenge than we ought to face on the Moon.

I really don't think that "mass spectrometry" really fits what we want to do, either, as that is primarily a technique for identifying the chemical composition of a sample whereas what we want to do is separate it into its components and recover the hydrogen, carbon, etc. for our use. However, I'm not enough of a chemist to suggest a workable process for doing this on an industrial scale.

I don't have much faith in calutron like devices, but some people do. We will see what future research yeilds.

On a different subject, how to we build RR trains on the Moon? Rails would be of steel made by the blister steel or cementation process. See: http://www.moonminer.com/blister-steel.html and http://www.moonminer.com/Blister_Steel_2.html

We might get some manganese to make the rails harder.

What about gravel beds and ties? I think it might be possible to bull doze away rocks and compact the surface with a heavy steam roller then use microwaves to melt the surface and let it harden into slabs of basalt. Then we bolt in the rails. Might as well make a wide or std. gauge RR than a narrow gauge. Yes, std. gauge RRs are based on the width of a Roman chariot and two horses, and there is a joke about that. We will select a lunar std. gauge based on something more relevant.

Then there's all those problems with road bed cracking, rail expansion and contraction during the Sunth or lunar day/nite cycle. Say we solve all the problems, at what point in lunar development do we build RRs? This could start a debate. Others have told me we should start right away. I think we will have to wait until the lunar industrial seed has grown to a point at which we can produce enough steel, build the dozers, graders and compactors on the Moon, and support a work gang in buses and trucks to haul and lay down the tracks unless we do it all with robots teleoperated from a manned base.

We also must consider monorails. At least then we won't be building a solid bed for the rails but just digging holes and sinking in posts that support the single rail.

We must think about power supplies too. Is regolith conductive enough for us to get a good ground for AC current? Or must we use a two wire system to complete the circuit?