Designing a practical lunar base is hard

A couple of months ago, I had an idea for a story following a guy around as he did some “weekend” chores, like checking the smoke detectors.  Why would anyone care for such a story?  Because he’s a crewmember of the first lunar base.  Since going to the moon is so difficult, the crew works for six days, and then they have a half-day where they finish up their experiments, do some minor maintenance and cleaning, and usually watch a movie.  This week, it’s my character’s turn to do the safety checks: each room has a detector unit for smoke, radiation, pressure drop, carbon monoxide, and probably a few others.  He also does a visual check to see if there are any cracks in the walls.  Every few months they do a more rigorous check with a laser system, but that’s not this week. 

In the story there is no alien invasion, or some secret plot to destroy the base.  Nothing like that.  It’s just a group of people learning to live on the moon.  For example, every week each crewmember gives a blood, urine, and stool sample.  Some tests are run there on the moon, but most of the samples are frozen to be shipped back to Earth where dozens of tests can be run.  Because we have barely any data on what living at the reduced lunar gravity will do to humans.  It’s necessary science, but not the premise for a blockbuster. 

Anyway, I decided that I needed to come up with the layout of the base to keep everything straight as he walks around and sees all the various ongoing experiments.  My initial design had seven modules the size of what could fit in a rocket.  The idea was they would launch and dock with a small space station that would probably only be temporarily crewed.  There it would be attached to a lander that would fly it to the moon and land it.  This lander, once unloaded, could then lift off from the moon, dock with the station, be refueled, and go on to land the next module. 

The first thing to land, however, would be a bulldozer and a 3D printer.  The printer would take lunar regolith, mix it with some binding agent, and basically make lunar cement.  The idea of the cement was to build an airtight, protective shell around the modules, which would then be covered over in more regolith to give radiation and micrometeor protection. 

So a foundation would be printed out, then the seven modules would land and be placed.  The seven modules would be arraigned like a straight-sided “8.” The module furthest in would be the sleeping quarters with a galley, the one in the middle would be the greenhouse, and the one with access to the lunar surface would have the airlocks.  And the other four would have labs, storage, command center, common area, etc.  In addition, the two interior holes would be used.  They’d have a cement floor and ceiling, but the walls would be the outer layers of the modules.  They’d have air in them, but they’d just be used to store spacesuits, extra oxygen tanks, and other bulky stuff.

Originally, the plan was for the base to be built by robots before people showed up, but I figured that since this was going to be difficult enough as it was, having boots on the regolith to make sure it actually fitted together correctly would speed things up.  Because the more I thought about it, the more complex and expensive this first base was becoming.  So we have the bulldozer and 3D printer needing a rocket launch, along with the lander.  Then each module needs a rocket, along with a few refueling tankers for the lander.  Then there’s solar panels, a rover, communications antenna, and we quickly get to maybe twenty rocket launches just to get everything to the moon, not counting the people.  We’re talking at least a year, or maybe two, to build the base.  But could such a big, expensive project actually survive long enough to be built?

In an attempt to make things cheaper and faster, my second plan was to land a small outpost – either just a couple modules or maybe an expandable module – that would just be on the surface with no 3D printed lunar cement thing around it.  This outpost may only be temporarily crewed, but one of the things they would do would be to work on building the second base.  This would be mostly 3D printed lunar cement, with the only things built on Earth being a bunker module as well as all the airlocks and airtight interior doors.  This lasted for a while, but then I realized that it would be stupid to just abandon this first outpost, so the current plan (Version 2.1, I guess) is for the first outpost module(s) to become the bunker module with the rest of the base 3D printed around it.  This would be the permanently crewed base my story is set in.  Their main goal is to learn how to live on the moon in order to build even bigger bases. 

“That’s cool,” you – hopefully – say, “but why is designing a practical lunar base hard?” Even with 90% of the base being built with lunar cement, there are still many literal tons of stuff you have to send to the moon.  You’ll need a bulldozer to clear the area, sensors to make sure the area is compact enough to build on, the 3D printer, something to gather the regolith, something to shift it to get the proper sized grains, maybe a grinder to break up rocks to the proper size, something to mix it with the binding agent, and all the binding agent.  And do all of these things have solar panels, or is there a central power station all these things return to to recharge their batteries?  Then there are the big things like hatches that are built on Earth and set into the 3D printed walls, but what about lights and all the wiring that goes with them, and ventilation, and toilets, and all the computers and microscopes, and all the plumbing for the hydroponic system?

Just take a minute to think about electrical wiring.  Long before anything is actually built on the moon, the base would be designed in a computer on Earth.  So in the computer you could see that this one wire would need to be 17.3 meters long.  So do you make a wire that long on Earth, tag it as “Wire 17R-14J” or whatever, and ship it up to the moon with a few hundred other lengths of wire that are just pulled out when needed?  But what if something unforeseen comes up and it ends up a centimeter short?  Do you include a wiggle factor of, like, an extra five centimeters for every expected meter in length, just so nothing ends up short?  Or do we just send a couple 100 meter rolls of wire to the moon and let the astronauts cut the appropriate lengths?  A benefit of doing all this on Earth is you could have basically plugs on each end to plug everything together, without the astronauts having to strip the wire and actually make the electrical connection.  Both ways have their pros and cons, but which would be the best choice?

You could just set a story in a base that is fully furnished, but you do have to wonder how it all got there?  What elements were delivered first?  Did they land a package with all the hydroponic stuff, 3D print the greenhouse around it, and once they were sure it was all airtight did they go in and unpack it?  Or did they 3D print the rooms, leave them empty, and just fill them as they landed the cargo?  To see the final design, I needed to figure out how they would actually build this base.  Part of the reason is that in such a complex process, there are bound to be quirks, like even with virtual walkthroughs, once there is a crew at the base they will wonder why the engineers didn’t put the door two meters that way.  And by working through the building process, I can pick up on some quirks to make for a richer world building.  So, this is the construction plans I came up with.

Step 1: Land the original outpost and basic equipment.  This outpost would be crewed for one to two week missions every few months.  They would do extensive surveys of the area to make sure there were no hidden caves or anything like that.  They would also test print some small structures to see how they survive the extreme day-night cycle on the moon. 

Step 2: Print the bunker foundation.  The foundation of the base would probably be twenty or thirty centimeters thick, at least.  But it probably wouldn’t be solid, because that would need a lot of binding agent.  I’d guess there would be two air pockets in the foundation, with ten centimeter wide pillars spaced every meter or so.  Why two air pockets?  Well, in the bottom one you could pump in some non-dangerous but easily detected gas with sensors in the upper pocket to check for leaks.  And you could pump the upper pocket full of air to be used as an emergency air supply.  This might also be done with the interior walls.  Let’s face it, the first lunar base will be overdesigned for safety.  Like I imagine every section will have several emergency spacesuits that you wouldn’t want to go out on the surface in, but in a worst case scenario they would keep you alive for an hour or so for you to get to somewhere safe or to find a proper spacesuit.

Step 3: Finish the bunker.  Once the foundation is set, the original base would be lifted up and set on the foundation.  The original base would have a hatch that a detachable airlock could be hooked up to.  The airlock would be taken off, and an extra thick wall and ceiling would be 3D printed around the, now, bunker.  Another hatch would be set into the wall, and the airlock would be attached to it.  So now you’d go through the airlock and end up in a small, lobby before going through the inner hatch to end up inside the old base.  All the science equipment and such will eventually be moved out, and the space refit as crew quarters.  Spacesuits and other bulky equipment could be stored in the lobby.  This bunker section I’m calling Section 1.

Step 4: Make Sections 2-5.  The final base will be a two-level dome.  The bunker is in the very center with four sections around it and an upper floor section.  For Section 2, you’d print out a foundation several times larger than for the bunker.  There would be several interior rooms that may, or may not, be airtight.  But the section as a whole would be airtight.  There would be two more hatches leading to Sections 3 and 4.  The airlock would again be removed and switched to one of these hatches.  Section 2 will ultimately be the greenhouse, but until everything else is built, it is also the command center, galley, storage area, etc.  Section 2 will also have the primary bathroom because the hydroponic garden will be connected in with the water purification system.  Section 3 will be the command center along with the galley, pantry, and other storage.  Section 4 will be the labs, and Section 5 – besides being the primary spacesuit storage/maintenance area – will have the airlocks.  There will be person sized ones, but also a larger cargo airlock.  I imagine there will be a minivan-type rover that will be able to take several crew members some distance, but there will probably also be a pickup-type rover for cargo.  A cargo ship will land, and instead of making forty trips through the person sized airlock, they’d just load up the pickup and drive it in.  You’d need something more than just a wagon, because some of the cargo will need to be refrigerated or frozen, and any biological cargo – plants or lab mice – will need some life support. 

Step 5: Make Section 6.  The main part of the upper floor will be the common area.  This would have couches and a big screen TV so the crews could watch movies.  This would also be the area where they would talk to kids back on Earth from.  There would also be private rooms that would be soundproofed.  That way crewmembers could have videochats with loved ones without someone walking through the background.  And there would be storerooms.  Sections 3 and 4 will have ramps leading up to Section 6, with hatches on each end.  And there will also be a cargo elevator that will be airtight, somehow.

Step 6: Finish the dome.  So the outer walls of Sections 2-5 and the wall/ceiling of Section 6 would form the inner dome.  Around this would be several walkways wide enough for someone in a spacesuit to walk around for inspections.  An outer dome would be printed around this.  And then, on the outer dome would be attached these 3D printed baskets.  These would probably be roughly cubes a meter on a side.  The sides would be ten centimeters or so thick, and the inner and outer walls would be curved to fit the dome.  These would be filled with loose regolith – to save on binder agent shipped up from Earth – and then stacked on the dome.  They might even do two layers of this because, well, overdesigned for safety.  And if one of these baskets was damaged, it could just be removed, print a new one, and replace it.

Step 7: Other stuff.  There will probably be a garage, but it will probably just be a roof to protect the rovers from micrometeors.  If any repairs need done, they’d drive them into the cargo airlock.  There will probably also be a garage/recharging area for robotic rovers, which I imagine will do the majority of outside work.  There will also be science areas, like the surface of the moon is a higher vacuum than we can make on Earth so who knows what possibilities there are for manufacturing.  Part of the reason for this first lunar base is to work out what can be done before building full-scale lunar factories. 

So is that what the first lunar base will look like?  Unlikely.  Which is too bad.  In my armchair moon architect eyes, I think that would work really well.