Redesign the LM as a class project

[ka9q]

Does anyone here actually teach classes based on Apollo as a case study? Jay seemed pretty knowledgeable about it, so I figured maybe he's done it.

Here's an idea that occurred to me that might make a fun project for a space systems engineering class: do a preliminary study on the modifications you'd make to a stock Apollo LM to increase its lunar stay time as much as possible. You're encouraged to update the subsystems to modern technology, but the overall structure, function and mass have to remain essentially the same. I.e., it should still be able to fly in a Saturn V (if we had one flight-ready).

I know how I'd personally approach a project like that, but I bet some engineering students would come up with some brilliant ideas that wouldn't even occur to me.

[capricorn1]

I Would have a large 'half tent' like structure that is really easy to erect, lightweight highly reflective material that puts the whole LM in the shade. Just open it out if the LM gets too cold.
I would have solar panels to collect energy to power the electrics and recharge the LM batteries. Easily deployed, you wouldn't need that many.
I would set the LR also to be powered by solar power as a hybrid alongside rechargeable batteries.

[echnaton]

After saving battery weight through a combination of capricorn1's solar panels and using lithium ion batteries, I'd extend the surface time by saving water through the use of a radiative cooling system to augment or replace the sublimator. Perhaps further aided by capricorn1's parasol.


Using lithium ion batteries on the LR could turn it into the Tesla Roadster of the moon.

[ka9q]

Since electrical power was so tight I too would put a deployable solar panel near the top of my list. I often wonder why one wasn't included on the later J-class missions.

I suspect that a revamping of the LMs avionics would save so much power that this alone would greatly extend the water and power supply.

Of course, a major part of any such study would have to start with numbers: the actual amounts of consumables and their consumption rates, and how they could be changed with new technology. For example, what did the LM consume in its powered-down lunar stay state? During the EVAs it consumed no O2 at all, though it had to later refill the PLSSes and repressurize the cabin. And so on.

If you want some *real* fun, figure out what would be required to keep the LM and its crew alive during a 2-week lunar night. Here I don't see any alternative to nuclear power; the plutonium fuel for the SNAP-27 RTG dissipated about 1.5 kW, on the order of the waste heat produced by the powered-up LM, so if you're really careful you could use one to stay warm. You'd still need electricity and other consumables to get you through what is likely to be a non-productive period, though.

[Apollo Gnomon]

For the "overnight" stay, the parasol could be reconfigured to trap radiating heat back into the LM - sort of a thermal tent for both hot and cold modes. Mylar and fiberglass poles.

The weight savings of modern electronics would go a long way.

[ka9q]

That's a really good idea, I'm glad I thought of it! :-)

You could erect a tent or tarp of aluminized Mylar or Kapton over the LM so that it couldn't see black sky. It would still see the surface, but the top layer of regolith has a pretty low heat capacity and conductivity so it probably wouldn't soak much heat away into the ground. This would all have to be calculated, of course.

But now that I think about it, would all this really be necessary? The LM already has excellent insulation in both stages. The insulating blankets are obvious on the descent stage, but I think the ascent stage has a similar thermal design; the blankets are merely hidden by the thin metal panels that form the outer micrometeoroid shield for the crew cabin.

As I recall, some of the projections (particularly the RCS engines) do get quite cold and were supplied with electrical heaters. During translunar coast they were powered by the CM through an umbilical to conserve the LM batteries.

I think surviving the lunar night will be entirely about electrical power. Batteries aren't big enough even with solar panels to charge them during the day. Even fuel cells might be pushing things unless they can be reversed and operated as electrolyzers from solar panels during the day to store H2 and O2. That means you need either very large gaseous storage tanks or some way to liquify the O2 and H2.

It sure would be a lot easier if you could just carry a small nuclear reactor...

In-situ O2 generation should be a very high priority in any return to the moon. Half the moon's crust is oxygen! Practically every chemical component of the soil is an oxide, silicate or titanate, including ilmenite, iron/magnesium titanate, that is especially easy to process into free oxygen.

The advantages of using what's already on the moon instead of hauling it up with you from the earth seem so overwhelming that I can't understand why it wasn't a major part of Constellation.