This moonbase condo had a much better view in the brochure!
March 24, 2015 3:50 PM   Subscribe

Always dreamed of living in a moon base, with a view of Earth and the stars out your bedroom window? Well, you may end up living in underground lava tube instead. The moon's lower gravity means that lava tubes wider than a kilometer could remain structurally stable there.
posted by Blue Jello Elf (42 comments total) 9 users marked this as a favorite
 
Think the Selenites might have other ideas about you building a condo in their lava tube, dude
posted by misterbee at 3:57 PM on March 24, 2015 [3 favorites]


Future headline: "Millions killed when lunar lava tube collapses."
posted by ColdChef at 4:00 PM on March 24, 2015 [7 favorites]


Gee, this coupled alongside my fear of underground spaces, what could possibly go wrong?
posted by Kitteh at 4:03 PM on March 24, 2015 [1 favorite]


...what could possibly go wrong?

Well, that bloody monolith could move in next door.
posted by mandolin conspiracy at 4:24 PM on March 24, 2015 [5 favorites]


Neat!
posted by brundlefly at 4:25 PM on March 24, 2015


So, when they say stable, do they mean stable enough to pressurize? If not, what's the benefit? Radiation shielding? Micrometeorites? Evil villain lair-appeal?
posted by leotrotsky at 4:33 PM on March 24, 2015


There are so many steps that need to happen before this has any chance of even being tried, it's ridiculous. Plus who wants to live in cave, even a giant one? May need to perfect holographs to really make this work. Showing a blue sky instead of oppressive, omnipresent darkness would do wonders for making this palatable.

At least until that first meteor strike.
posted by Brandon Blatcher at 4:39 PM on March 24, 2015


what's the benefit? Radiation shielding?

As stated in the article, yes. Lacking an atmosphere, long-term colonists would need protection against cosmic radiation. Rock is likely the best option. A lot of rock.

I did a calculation once, long ago, of how much rock would be needed. I vaguely seem to recall that 25m of rock would provide excellent protection. If you already have a nice big lava tube you don't need to go to the time and expense of digging out a shelter that deep.

Plus who wants to live in cave, even a giant one?

Have we mentioned that the cave is on the frikkin moon?
posted by justsomebodythatyouusedtoknow at 4:44 PM on March 24, 2015 [14 favorites]


My big question is: what does Perdue have against Philadelphia that they enjoy imagining it banished to the moon? Surely Indianapolis would be a better bet for that....

May need to perfect holographs to really make this work. Showing a blue sky instead of oppressive, omnipresent darkness would do wonders for making this palatable.

Some say "oppressive, omnipresent darkness," others say "welcome cover from the angry eyes of the stars." Don't be so judgy.
posted by GenjiandProust at 4:44 PM on March 24, 2015 [13 favorites]


So, when they say stable, do they mean stable enough to pressurize? If not, what's the benefit? Radiation shielding? Micrometeorites? Evil villain lair-appeal?

Pressurization would actually help hold them up. But you'd be better off putting something sealed inside of them rather than trying to plug all the holes. Indeed, Standard Model #1 of a lunar base is "put up a long half-tube shaped structure and cover with lunar fill." Finding a lava tube basically saves you the work.

As to why? Rad shielding and micrometeorites are two big reasons, though never doubt the evil villain lair appeal aspect. Thermal management is critical as well. Without an atmosphere, you're in a pure radiative thermal environment on the surface, which means the big factors in your life are the 5800K sun when it's up and the 3K sky when the sun isn't up. Get in a cave and you don't have to worry about the freeze-melt cycle as much.

You might also be away from the other huge problem on the moon, which is the dust. Without wind or water, all the micrometeorite impacts have loaded the regolith with an incredibly fine dust -- it's as fine as powdered graphite, but unlike graphite, it's *very* abrasive. One of the big problem the lunar landing missions had was they started having things jamming from dust contamination in hours.

Anybody thinking about living on the moon really should really all of the Apollo Lunar Surface Journal, which is an annotated communications transcript of all the surface activity of the lunar landing missions, along with flight planning documents, image libraries, debriefings, etc. The transcripts were also reviewed later by the astronauts, capcoms, flight directors, and other participants, leading to other aspects of the program. Fascinating detail -- and yes, there's a page for Apollo 13, with the flight plans and such.

The reason to review this material is you'll see the problem *they* had, so when you're planning your lunar missions, you'll know what you'll need to address. And one of the big things you are going to have to address is the damn dust. It's incredibly tenacious, and it causes all sorts of problems -- mechanical and thermal we know about, and who knows what long term health issues there might be.
posted by eriko at 4:47 PM on March 24, 2015 [26 favorites]


The thermal stability can be both a plus and a minus. I have no idea what the moon's internal temperature is, but craters at its poles were measured at -240C. I suppose an area exposed to sunlight won't get that cold, even a hundred meters or so down, but it will still be cold. So a base dug sufficiently deep will need to be well insulated anyway, and it may have problems caused by extreme temperature differentials between the base's exhaust heat and the walls surrounding it.
posted by Joe in Australia at 4:58 PM on March 24, 2015


Insulation isn't hard -- you're in a hard vacuum, if you're in anything with pressure, you're quite literally in a vacuum flask. Indeed, the problem isn't staying warm, it's staying cool -- there are more than enough things inside generating heat, including the people. A lunar surface base can possibly sink heat into the moon proper, but most base designs assume that we'll need active cooling, like we did for Apollo.

The Apollo spacecraft and the A7L space suits used water (well, ice) sublimation for cooling, which works well, but requires water. STS, ISS and Soyuz use radiators, which work as long as you can keep them in the shade, but a simple sun shade is enough for that. Radiators mass a lot more than sublimator, which is why Apollo used sublimators.
posted by eriko at 5:22 PM on March 24, 2015 [4 favorites]


Plus who wants to live in cave, even a giant one?

[raises hand] I'd love to see humanity move underground, and somewhat more realistically (although still not very) human agriculture move into massive underground vertical farms. Leave the surface for the animals and national park-style spaces. We're the primate equivalent to an ocean-wide toxic algae bloom, and our biosphere deserves a vacation.
posted by Ryvar at 5:22 PM on March 24, 2015 [5 favorites]


[raises hand] I'd love to see humanity move underground..

Ryvar, I think the Morlocks might have other ideas etc etc
posted by misterbee at 5:29 PM on March 24, 2015


This from the Boilermakers? No thanks.
posted by Samuel Farrow at 5:44 PM on March 24, 2015


Plus who wants to live in cave, even a giant one?

People live in Las Vegas. Just put a sun roof on it, and there ya go.

The BIG question though, is whether we can survive long-term in 1/6 gravity. If that's enough to prevent bone loss, great. If we need a full G to survive, then it's probably not going to be worth the effort to try to colonize the moon.
posted by happyroach at 5:45 PM on March 24, 2015 [1 favorite]


People live in Las Vegas. Just put a sun roof on it, and there ya go.

Yeah, not quite.

Humans don't live underground. even on our home planet, we're just not built for that. I'm skeptical of us doing it an alien environment. Plus eriko's right, the dust could be a showstopper on any permanent settlement on the Moon. Never mind that no one has answered the question of why humans would settle there.
posted by Brandon Blatcher at 5:57 PM on March 24, 2015


Insulation isn't hard -- you're in a hard vacuum, if you're in anything with pressure, you're quite literally in a vacuum flask.

Sure. But you're in a cave. You have rock walls leaning over you at a temperature of (say) -200C. You're exhausting waste heat somehow - radiators? pipes embedded/along the walls? Those walls start to heat up and expand. Are they necessarily going to remain stable? So my point is, you have similar insulation issues as you would on the surface, plus you're exposed to the risk of a cave collapse.
posted by Joe in Australia at 6:01 PM on March 24, 2015 [1 favorite]


My hypothetical New Yorker cartoon is a realtor showing a young couple an apartment on the moon and the caption is the wife saying "We were hoping for something with a little more atmosphere."
posted by snofoam at 6:20 PM on March 24, 2015 [21 favorites]


Vacuum industries and mining would be the two obvious big potential industries I can see benefiting from, or being the direct driver of, a permanent moon base. Science would obviously derive a lot of benefit as hangers on to an industrial base. And there would be significant tourism as well if the costs were obtainable (even if by only the 1%ers).
posted by Mitheral at 6:26 PM on March 24, 2015


I was immediately reminded of the Heinlein story "The Menace From Earth", which features a very large (as in kilometers), roughly spherical cave which the colonists have sealed and filled with air. Basically they turned it into a park, and because of the low gravity, they strap on wingsuits for recreational flying.
posted by George_Spiggott at 6:31 PM on March 24, 2015 [2 favorites]


Amazon Mole Women On The Moon!
posted by robocop is bleeding at 6:33 PM on March 24, 2015 [1 favorite]


My big question is: what does Perdue have against Philadelphia that they enjoy imagining it banished to the moon?

Moon cheesesteaks. Makes total sense.
posted by Drinky Die at 6:49 PM on March 24, 2015 [2 favorites]


Wouldn't the presence of non eroded, lunar dust just slice everything to ribbons and foul all the gear whether you were above or below the surface? Plus, it smells
posted by Conrad-Casserole at 6:53 PM on March 24, 2015


Never mind that no one has answered the question of why humans would settle there.

Ding ding ding ding ding ding.

That's the big question. Right now, there are basically no compelling reasons to go to the moon other than science, and probes are a lot cheaper. Blah blah helium 3, but again, robot mining would be the path to go, and let me tell you, mining machinery + abrasive dust = fun!

Because it's there was solved by Armstrong & Aldrin. You can make an argument for sending a few more geologists, because how the Moon was made is intimately tied into how the Earth was made, and a smart geologist with a hammer can do a lot of work that a probe wouldn't know needed to be done -- just ask Jack Schmitt. But you can counter argue that a few dozen probes would solve that.

Mars, at least, you can at least pretend that sometime you'll be able to live on the surface without a pressure suit. That will never happen on the moon, or anything moon sized. While .16g is good for many things, but not for holding a nitrogen-oxygen atmosphere down.

The hows are fun to argue in an engineering sort of way, but really, it's all fantasy without a why, and when it comes to the big bright nightlight in the sky? It was a nice place to visit, but you really don't want to live there.
posted by eriko at 7:00 PM on March 24, 2015 [3 favorites]


Joe in Australia:
"Sure. But you're in a cave. You have rock walls leaning over you at a temperature of (say) -200C. You're exhausting waste heat somehow - radiators? pipes embedded/along the walls? Those walls start to heat up and expand. Are they necessarily going to remain stable?"
Compared to the thermal energy dumped into those same cave walls from the outside by the sun on a (lunar-)daily basis a moon base's heat output is going to be negligible. Even if it weren't insignificant... since the cave walls aren't free floating but continuously connected to the rest of the lunar mass the entire moon acts like a heat sink limited only by how quickly thermal energy can diffuse through the material. Just like using 20' geothermal heat pumps for air conditioning won't cook the roots of all the plants around the building.

If these structures are found to exist and haven't yet collapsed they won't be affected by some extra heat after withstanding endless cycles of crazy temperature variations between lunar day and night.
posted by Hairy Lobster at 7:08 PM on March 24, 2015


Luney Tombs.
posted by Chitownfats at 7:18 PM on March 24, 2015 [5 favorites]


Vacuum industries and mining would be the two obvious big potential industries I can see benefiting from, or being the direct driver of, a permanent moon base.

The Pentagon would love the chance to buy container loads of $5 million thermoses from the moon factory.
posted by Dip Flash at 7:24 PM on March 24, 2015 [1 favorite]


> There are so many steps that need to happen before this has any chance of even being tried, it's ridiculous. Plus who wants to live in cave, even a giant one? May need to perfect holographs to really make this work.

That problem was sorted fifty years ago. Ever read Philip K. Dick?
posted by ardgedee at 7:27 PM on March 24, 2015 [2 favorites]


[raises hand] I'd love to see humanity move underground, and somewhat more realistically (although still not very) human agriculture move into massive underground vertical farms.

I mean this nicely, but WTF? Agriculture depends on sunlight for energy. How does moving it underground work?

(Also, where do you put the spoils from digging all those vertical farms? Right now farming uses about 40 percent of the earth's surface, so you will need an awful lot of farm-caves, which means producing a lot of extra dirt when you dig them.)
posted by Dip Flash at 7:48 PM on March 24, 2015 [3 favorites]


I mean this nicely, but WTF? Agriculture depends on sunlight for energy. How does moving it underground work?

Most proposals along these lines require a light source on the underside of each plate in the stack. The general idea is to min/max plant growth and crop yield with carefully tuned light wavelength (Ctrl+f "underground").

Right now farming uses about 40 percent of the earth's surface, so you will need an awful lot of farm-caves, which means producing a lot of extra dirt when you dig them.

The majority of that is supporting livestock, not crops.

The actual volume of earth displaced is fairly low since you'll still need soil but you'll be biasing crop selection toward plants with lower height for volume efficiency reasons. The amount of earth moved is still massive, however, because even if 60% of the vertical farm's volume is still soil, that remaining 60% is humus-enriched topsoil. Which means 100% of the volume needs to be excavated and then 60% needs to be imported.

Assuming 0.75m per layer (you need some clearance for the planting and harvesting equipment to move freely) and a maximum depth of no more than 300m to keep the engineering challenges down, you're looking at a 400:1 area compression ratio. If yields can, as PlantLab claims, be increased 3x with carefully tuned lighting and atmosphere and an additional 2x between genetic modification and more intelligent crop selection we're looking at a 2400:1 compression ratio. Worldwide arable land 14 million sq km/ 2400 surface:vertical farm ratio = 5833 sq km (roughly twice the Tokyo metro region) that you need to excavate down to a depth of 300 meters, for a total earth moved of 1750km^3. To put this in perspective: the entire Panama Canal project moved 0.2km^3 of earth.

Needless to say, if the lighting aspect wasn't happening without fusion power, the earth movement sure as shit wasn't happening without fusion power.

We now return you to your regularly scheduled moonbase thread...
posted by Ryvar at 8:55 PM on March 24, 2015 [3 favorites]


Oh, and to head off the obvious objection at the pass with the obvious answer:
The back-of-the-bar-napkin math above does not factor in a fairly significant number and thickness of dividing walls because you're absolutely going to need to adopt a honeycomb-style cell approach to limit the potential spread of diseases.
posted by Ryvar at 9:02 PM on March 24, 2015


I would like to remind all the detractors that, as previously stated, in a large pressurized moon cave you could strap on wings and fly unaided. I'm willing to give up blue skies and weather for that.
posted by Mr.Encyclopedia at 12:36 AM on March 25, 2015 [4 favorites]


Why does it have to be a permanent home? The moon is the perfect place for a vacation. I'd totally go for 2 weeks, try out the kilometer high roller coaster, drive the moon buggy and visit the historical whaling sites, strap on some wings and fly (ala Mr.Encyclopedia), etc.

We just have to get the round trip transportation costs a tad lower.
posted by Poldo at 5:10 AM on March 25, 2015 [3 favorites]


I would like to remind all the detractors that, as previously stated, in a large pressurized moon cave you could strap on wings and fly unaided.

While I'm increasingly doubtful humans will ever reside on other planets, I wouldn't bat an eye about spending 200-400 billion to try and build a permanent Moon base. Because hey, SPACE COLONY and what not.

However, the reality is that there's no strident or urgent need for one. It would be very cool, lots of interesting science would be done and it would incredibly moving to see humanity exploring another body. But to live off world is nothing like the romantic notions that fiction has conjured up for us. The sooner we drop some of those illusions and realize it's going to be hard, dangerous and expensive work, but it's worth doing anyway, the better.

Elon Musk is doing some great stuff with Space X, but I do wish he was focused on the Moon and not Mars. The red planet is whole 'nother kettle of fish, while the Moon is clearly within our grasp. I don't want to go to the Moon for the thrill of flying in large cave (though it would be nice side benefit if possible). I want humanity to develop a plan to stay on the Moon and use it as a launchpad to explore the rest of our solar system.
posted by Brandon Blatcher at 5:48 AM on March 25, 2015


Elon Musk is doing some great stuff with Space X, but I do wish he was focused on the Moon and not Mars

Can't agree with that. If you have to have a silly impossible fantasy, at least have one with an endgame. Musk's endgame is colonization. You will *never* be able to truly colonize the moon. You will always need the Earth. There's just not enough mass, not enough hydrogen, not enough oxygen, and not enough carbon.

On Mars? There may be enough. Mars is rather small. This image from Wikipedia really shows the issue. Half the mass of earth, less than a sixth of the volume, just under a fourth of the gravity.

But: Mars has Oxygen and Hydrogen. Mars has water, at least in ice form. In terms of human survival, that's huge. That one fact alone make Mars the single best target, by far, for human colonization. The #2 fact is the day length. We are *really* attuned to a day-night cycle, and we get really screwed up if it's wrong. So, the fact that the Martian Sol is 24 hours 37 minutes and change long is also a huge win -- we can adjust to a day that averages 18-19 minutes longer, heck, most of us see far more daylight variation over the year due to the Earth's axial tilt.*.

It's cold, the atmospheric pressure is too damn low, carbon seems to be lacking, there's little UV protection, and while there was a global magnetic field, there isn't now. The lack of compasses is an annoyance, the lack of a magnetosphere protecting against cosmic rays and solar storms is a big deal.

Mars also has enough of an atmosphere to have wind. Wind helps with the dust problem by moving it around and beating it against each other. This makes it smoother, and fines end up wedged in crevasses. It's clear the dust problem will be much less on Mars, look at how well the various rovers have roved. The one big problem the dust has caused has been covering solar panels, which is one reason Curiosity has an RTG for power instead.

I get the fascination with the moon. It's right there. It's so big and bright, Mars is so faint and distant. But Mars? Mars might be habitable. Mars might even have life?

The moon? The moon is dead. So far, it's not even useful as a mine. It's pretty, but that's it. It wouldn't even make a good intermediate base to anywhere else, because of the ΔV you need to land, and then take off again. If you want that, you build that in Moon-Earth L1, where just a tiny kick puts you at Earth Escape, not the 3km/sec you need to get down from LLO and back up again.

We had to go -- we had to find out. But, we've been. We've send a lot of probes, there are a few orbiting right now, and the new spacefaring nations are sending more -- it's a great 3rd/4th step, after LEO and GSO -- China has three orbiters now, India sent one, Japan sent one, China has soft landed and sent a rover, which worked, briefly.

But really, the only reason to land on the Moon is to say you've landed on the Moon. For the US, that square is filled. China is obviously aiming to do so, but this is strictly as a matter of pride. **

Mars is hard. Mars may well be impossible -- but it's not *certain* to be impossible to live on the surface. It is impossible to live on the surface of the Moon, and it will always be so.

Indeed, if we could fix the rotational period, the one planet best suited, surprisingly, is Venus! Gravity is .9g! Get it close to one day, soak out the CO2 and get water there, and Venus rapidly becomes Earth 2. Of course, I've just asked for not one, not two, but *three* miracles. But in terms of making an Earth, size counts, and the closer to 1g you are, the easier a breathable atmosphere and liquid water becomes. If Mars was .7g, rather than .4, it would probably have liquid water. Then again, it might well have Martians, and we'd be looking at a very different question then.


* The question is how do we work the clocks? Easiest is to lengthen the second a smidge, which would lengthen the minute and hour, but we have the second as a fundamental unit. Kim Stanley Robinson's Mars Trilogy had them using the standard Earth 24 hour clock with a 37:22 "skip" between days, which has some attraction. It could also just be the 25th "hourlet". Another thing to do is have 25 59 minute hours, which would leave 30 second to deal with at the end of the day.

** Which, well, how do you argue against that? I just have a couple of thoughts. The Apollo 11 landing site? That's sacred. That's for all of humanity. That has to remain untouched. Please, China, don't go there.

But Apollo 12? I think it would be useful to *everybody* to land there and bring back both a piece of Surveyor 3 -- just like Apollo 12 did -- and of the Yankee Clipper's decent stage and the ALSEP as a study of how material last long term on the moon. That's a unique bit of science, and I chose this sight because we'd get another datapoint with Surveyor 3.
posted by eriko at 6:27 AM on March 25, 2015 [10 favorites]


Oh. Ok.
posted by Brandon Blatcher at 6:41 AM on March 25, 2015 [1 favorite]


Kim Stanley Robinson's Mars Trilogy had them using the standard Earth 24 hour clock with a 37:22 "skip" between days

I no longer recall if he dealt with the problem of time zones. Assuming everyone on the planet experiences the time slip (a Philip K. Dick reference he thoughtfully included) simultaneously, then if they continued the Earth practice of having the clock synchronized to the local solar position (i.e. at 12 noon the sun is more or less overhead), then it would happen at a different hour in each time zone. This might be a little odd when traveling around the planet: having to remember that in Marsopolis it occurs at 8:00am and in Marinaris Meadows it happens at 17:00.
posted by George_Spiggott at 9:18 AM on March 25, 2015


(And BTW it is pretty important that everyone experience the time slip at once, otherwise clocks would be out of phase by 37-odd minutes in adjacent time zones, said phase-shift knocking around the globe like some novelty tabletop automata; not staggeringly complicated but still infuriating and impractical for purposes of coordination at any given moment.)
posted by George_Spiggott at 9:27 AM on March 25, 2015


The moon lacks methods of soil erosion and thus the soil is full of scratchy, clingly nanoparticles that can damage lungs over time. Not that Mars is better. It's probably worse because Martian soil apparently contains significant levels of calcium perchlorate, making it toxic to humans.
posted by xigxag at 12:46 PM on March 25, 2015


Assuming everyone on the planet experiences the time slip

Slip. Dammit, I knew I should have just gone and looked it up. Thanks.

Yes, it would have to be at the same time, but that's not incompatible with timezones. The timeslip has to happen between 2359UTC and 0000UTC (or, if you go for the 25 hour day, 2458 and 0000) because 0000 is the start of the new day. Part of your timezone information is when the timeslip happens in your timezone, so if you were at -6 UTC, because you were 77° west of the Prime Meridan of Mars, then the timeslip would happen between 1759 and 1800 for you.

However, if you can divorce your society from the idea that 0800=morning, you can ditch the idea of timezones, run the entire planet on a truly "Coordinated Universal Time", and the time slip happens between 2359 and 0000 everywhere.

But hey, I'll let the Martians figure that out.
posted by eriko at 5:23 PM on March 25, 2015


I no longer recall if he dealt with the problem of time zones.

The Mars trilogy kind of elided this. It was crucial to a couple of plot points that the timeslip occurred at midnight, but with time zones this would cause the different zones' hours to be misaligned. Of course in the very beginning there wouldn't have been a need for time zones because there was only one settlement, and then for a very long time everyone might have just used local solar time with a global Earth-based reference for synchronizing schedules.

The idea that the clocks stopped in the timeslip instead of continuing to tick and actually count the minutes was another kind of nod to PKD and some of the spiritual aspects of the story but nobody would actually implement it that way.
posted by localroger at 7:15 PM on March 25, 2015


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