Moon colonization – many lava tube caves, water and high amounts of titanium

The moon has many hundreds of large lava tube caves. The Lunar Reconnaissance Orbiter has now imaged over 200 pits that show the signature of being skylights into subsurface voids or caverns, ranging in diameter from about 16 feet (5 meters) to more than 2,950 feet (900 meters), although some of these are likely to be post-flow features rather than volcanic skylights.

There is a Sinuous of collapse pits transitioning into a continuous uncollapsed segment of a lunar lava tube. The chain is about 50 km long.

Inflatable module with a hard outer shell could be placed into tubes and they would be designed to seal the openings.

Any intact lava tube on the Moon could serve as a shelter from the severe environment of the Lunar surface, with its frequent meteorite impacts, high-energy ultra-violet radiation and energetic particles, and extreme diurnal temperature variations. Lava tubes provide ideal positions for shelter because of their access to nearby resources. They also have proven themselves as a reliable structure as they have remained stable for billions of years.

An underground colony would escape the extreme of temperature on the Moon’s surface. The surface can have big temperature swings from the day of 123 °C (253 °F) to night time −153 °C (−243 °F). Underground, both periods would be around −23 °C (−9 °F), and humans could install ordinary heaters.

Concentrations of titanium on the Moon range from about 1 percent to a little more than 10 percent. On Earth, the highest concentrations rarely get above 3 percent.

48 thoughts on “Moon colonization – many lava tube caves, water and high amounts of titanium”

  1. People are generally aware of how complicated it is to ferry basic and necessary equipment from Earth to the Moon in order to support human life — witness the Apollo program.
    But most do not think about how extensive and complex the manufacturing structure is on Earth needed to manufacture all that equipment to be moved to the Moon. In order to manufacture that needed equipment on the Moon, rather than bring it from Earth, would require that first an enormous manufacturing infrastructure be fashioned on the Moon itself.

  2. One thing that a lot of people don’t get is that nitrogen is missing and it’s a key element in amino acids and all proteins.

  3. No time to waste then. Lets fire up the Saturn V and go up to the moon. Why does NASA want to reinvent the wheel? Why do they stuff stuff like the conditions on the moon is lethal, and they need new spacesuits and shielding and so on?

    None of that stuff bothered the Apollo astronauts.

  4. Lava tube caves are a very good alternative at “Terraforming” because you benefit from large pressurized volumes very quickly and you gain an Earthlike environment difficult to create in a modular base (thing of trees for example). But in the short term the cost is much higher than a modular base sitting on the ground. All you need to do to have a safe level of protection against micrometeorites and radiation is built it close to a hill, a mesa or a dune and push dirt above it. Even big inflatables can do the job by being protected by a framework built around them to bear the load of lunar dirt (easy given the low gravity).
    But for tourism, those lava tubes would be great allowing lots of activities in a low gravity well.
    Within a century there’ll be a flourishing leasure industry “on” the Moon, because it is quick to come to and come from but the transportation means like BFR must come first.
    Without them this is a pipe dream.

    • I don’t even see a login link/button…
      I actually have al wordpress account and I am logged in to it but it doesn’t work on NBF….

      • Took a quick look at the page source; It looks like Brian has autocomplete shut off, otherwise your browser would at least fill in the name and email for you.

  5. This should be the goal.
    1. Fuel refinery on moon / Refueling station in orbit
    2. Asteroid mining
    3. Orbital space ship construction yard
    *4. Lunar Corporate Moon cave vacation home.


  6. I would suggest that real and practical design for a first-constructed outpost would be something more in line with today’s aircraft carriers or cruse ships. That technology is well proven and with nuclear power and solar collection, makes the possibility of an actual outpost within reach..

  7. The only things that would make any of this possible would be proven industrial returns and retirement for the rich in the much lesser gravity. With insertable and inflatable habitats… that’s a real game changer. Still, air conversion from the lunar materials would be the keys to self-sufficiency. A lunar colony or outpost just can’t be a tax-payer boondoggle.

    • Yes, you are right in the 20th century crony capitalist economy. However, the democratization of engineering and production that will happen this century with super-human artificial intelligence and robotics, and means even a family might be able to set up their own outpost…all they’ll really need is access to some raw materials and they can 3D print their own ship locally and station remotely. I think a lot of the incentives and motivations running the crony and exploitative capitalism of the 20th century have given the illusion of progress, but in the last 50 years, probably have stagnated progress from what it could be. This will change if technology becomes democratized. The possibilities will more rest with political and social issues, rather than technological.

    • Provided we don’t let crony capitalist like Bill Gates sequester all the IP under his intellectual feudalism, we’ll be in for good shape for the colonization of space on the cheap.

    • You’re missing the key change in the economy that’s impending: The transition away from production by human labor which is merely amplified by machines, to production by machines that run independent of human labor.

      Under the current model, production is unavoidably linked the the size of the human population, albeit with a multiplier that varies with technology. So for a group of people to enjoy some facility that is very infrastructure intensive inherently requires the labor of a large number of people, and everybody can’t enjoy things that take a lot of people to produce.

      But once production is freed of its dependence on human labor, the mass of infrastructure available to humanity will take off exponentially, at least until it reaches new limits imposed by readily available resources and available solar energy. Only a decade or two after the first self reproducing factory is launched into space, habitats like the above, and O’Neil colonies, will be so available that, while there will still be resource limits, (Not everybody can have their own personal relativistic star ship, even with the entire solar system for a resource base.) they will have very little impact on everyday life.

      • As someone who works on this subject, self-replication is hard. Systems that can grow from a starter set are not so hard. The difference is that self-replication requires making 100% of your own parts, and being 100% automated. Systems that can grow allow importing some hard-to-make parts or rare elements, and allow *some* human labor for difficult tasks.

        The latter is a done deal, we already have robots, machine tools, and foundries which can make many parts for more equipment. But a chip fab is highly specialized, so you likely would continue to import electronics because they are fairly low mass.

        Between the Moon and Near Earth Asteroids, you can probably find 98-99% of the needed raw materials for many common products. But some elements will be rare enough that importing from Earth will end up being cheaper. Those elements are likely out there, somewhere, but the Earth is vastly more thoroughly explored, so we know where the concentrated ores are.

  8. No sign of nitrogen on the moon which is why I did the calculation to see if it would be feasible to bring it as cryoliquid from Earth by BFR. It seems possible but will take hundreds of flights.

  9. Need nitrogen for atmosphere. Could we find some frozen ammonia in the shadowed craters – perhaps deposited by comets?

    • Nitrogen and Argon could both come from Mars at lower delta-vee than from Earth. CC Asteroids have some nitrogen compounds mixed in with the Kerogens.

      • You’re not getting Nitrogen from Mars; The Martians won’t have enough of their own to be exporting it. That will have to come from the outer planets’ moons.

        • Nitrogen from Titan?

          Sounds like something only feasible when self replicating factories are really advanced and printing out drones and facilities on the outer planets, making the cost of shipping all those volatiles affordable.

          Which is to say, probably not this century.

          But exponential technologies (like self replication) have some ways to surprise us. I suspect we are about to witness and accelerando of space technologies and utilization in the 2020s driven by new space companies and additive manufacturing…

        • I’m not sure why you say the Mars settlements will have problems. Mars’ atmosphere is 1.9% Nitrogen, and about the same for Argon. Just freeze out the CO2 after oxidizing the tiny CO percentage, and then liquify the rest to use as atmosphere and send any surplus to the moon as an export product. Cheaper than lifting it from Earth.

  10. But I think filling the entire cave with may be counterproductive. Huger hangar places like on the picture will need much less air to fill them and easier to maintain. I think 50meters hight is good enough. Large amount of iron and aluminum on the moon will come in handy for construction of all the support structures.

  11. You need indivisual houses to maintain temperature that you want in your house. The cave volume can be considered an outside environment as far as the house dwellers are concerned.

  12. The usual thing that artists do when depicting giant space habitats.
    They put small buildings, with roofs and windows and things, inside what is actually a big room.
    Why? We don’t add features like roofs and windows to small subsections of a big room. Something like cubicles or subdividers are used, or you build your smaller room into the same structure as the large room is made of. Nobody builds small houses inside big aircraft hangers or something that I am aware of.

    • It is done all the time in warehouses and factories. Gives office space with views over the word floor. Usually the roof is a deck and I’ve seen it used as break room with table and food, or just extra storage.

      • I’ve seldom seen it done any other way for offices on the plant floor. The roof/ceiling is important for noise control

    • “Nobody builds small houses inside big aircraft hangers or something that I am aware of.”

      That is true for the relatively small constructed spaces we build. However, in a space 100 meters wide by 50km long, there is a different perspective. If analysis of the data from GRAIL probes tells us sooth, then maximum diameters are likely to be as much as 5,000 meters, in some places. There, the idea of cubicles becomes figuratively “small-minded”. Among other things are the uses the space is put to. In these caves humans will not be just working 9-5, but *living*, ….permanently. I find it highly probable that the walls will not be obscured by structures, but instead will be covered by TiO2 crystals whiter than anything else available, and used as laser projection screens of scenes the residents want to see, ….from the stars overhead to pretty beaches, to snow-covered mountains. In other places, half the wall space could be given over to residences, while parks and other activity could dominate the floor area in a fully developed cave.

      • You have to keep in mind that, if they’re going to try to maintain any kind of vegetation in these colonies, they’re going to need “rain”. You don’t want the sprinkers getting your couch wet.

        Nor do you want the neighbor kid’s drone peeking in your bedroom…

    • Given there isn’t an ‘outdoors’ where you can go unprotected, and humans love such spaces, everything will have to be made ‘indoors’.

      The depicted dome seems too big for early settlement efforts, though, which would tend to use space and resources much more sparingly (and densely).

      The best great spaces they could expect to have at first are greenhouses with some botanic gardens or fish ponds (for food, not just decorative). Later, some more spacious domes or structures under the regolith, probably on one of these caves Brian refers.

      Kilometer wide domes would only happen when there is much more economy, infrastructure and people on the Moon, and when they have solved the problem of hauling all the required volatile elements like nitrogen and carbon.

      • Hey tchernik,

        How are you able to log on to use a WP account for your commenting? It won’t let me do it with my existing WP account…but other WP blogs do.

        • I think you also need a Gravatar account and use the e-mail you registered on Gravatar to post.

          You can use your WordPress account to sign up to Gravatar so that should be easy.

  13. I did a rough calculation how many BFR lights it would take to fill a 1 cubic km cave with air. Cryoliquid air to gas expension ratio is 750 to 1. Say BFR can bring 100 tons of cryoliquid air to the moon on one trip. One tonne of liquid air is equal to 1 cubic meter in volume that will expend to 75000 cubic meters of air or 0.000075 km3 or if we round it 0.0001 km3. Looks like it will take 10000 BFR trips.. Too many so would need to be content with a smaller volume in the beginning but a 1 times smaller volume is still substential especially if find some cave with low ceiling so could take a 1000 BFR trips. If you have a fleet of 100 BFR that is just 10 trips for each.

    • Humans don’t need sea-level atmosphere to survive.

      The Armstrong limit for survivable atmospheric pressure (with pressurized oxygen supply) is 6 kPa, but it’s not breathable. The minimum breathable atmospheric pressure is 12 kPa, though that requires a supply of pure oxygen.

      Maintaining a pure oxygen atmosphere at 15 kPa would be adequate for survival, but additional pressure would increase comfort.

      How to get that? We need a readily available neutral gas. Nitrogen is the most common. Another option might be CO2, but we can only sustain a partial pressure of 6kPa, so it can’t contribute much. It helps:
      12 kPa O2 + 6 kPa CO2 + 6kPa N2 ==> 24 kPa. This is the same atmospheric pressure as at 10,500m. There may be other gases available on the moon that could be used, though the possible selection is limited: neon, hydrogen, helium, oxygen.

      So basically only 600 BFR trips with 10 tons liquid N2 per cubic kilometer, though that could increase if 50% oxygen atmosphere is dangerous, or reduce if alternates for N2 are discovered on the moon or we focus less on comfort and only on survivability.

      • Probably don’t want to increase fire danger too much with high oxygen but if other noble gasses are available like they are on Mrs then we wouldn’t need to bring all that nitrogen.

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