Lava Tubes on Luna – Why build a lunar space station?


" … a graduate student in Purdue's Department of Earth, Atmospheric and Planetary Sciences, led the study that examined whether empty lava tubes more than 1 kilometer wide could remain structurally stable on the moon.

The Purdue team found that if lunar lava tubes existed with a strong arched shape like those on Earth, they would be stable at sizes up to 5,000 meters, or several miles wide, on the moon.

"This wouldn't be possible on Earth, but gravity is much lower on the moon and lunar rock doesn't have to withstand the same weathering and erosion,” Blair reported. "In theory, huge lava tubes — big enough to easily house a city — could be structurally sound on the moon."



Cosmic radiation is heavy on the surface of the moon.  Without a lot of shielding it will fry your innards.  This Purdue University study tells us that large, long, voids exist below the surface of Luna.  These were evidently created by lava flows long ago.  The study also claims that in the low gravity field of the moon, these tubes would be sufficiently stable to house a large lunar base for mining of rare earths and other activities.

This brings to mind the lunar colony in Heinlein's "The Moon is a Harsh Mistress."  In that novel, the lunar folk were miners whose mineral production was delivered to earth by being fired from rail guns at an impact area in the Pacific ocean from which they were retrieved by ships

For me the possibility of such a colony and base raises the issue of why the US and Russia are intent on building a lunar orbit space station.  Why could not anything that would be done in lunar orbit not be done at a lunar cave base?  pl

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53 Responses to Lava Tubes on Luna – Why build a lunar space station?

  1. JJackson says:

    I have no knowledge of such things but my guess would be the need for additional fuel. It would be required to decelerate anything landing and then again for anything taking off. If you were going to settle then the tubes seem ideal.

  2. Oilman2 says:

    My guess is fuel consumption. An orbital insertion uses much less reaction mass than a gravity landing. Space station parts go up once, then get assembled. Lunar building parts have to be lowered back into a gravity well after boosting to orbit, and no atmosphere for easy chute drop on the moon.
    However, since we have oilfield products that can coat a pretty thick plastic membrane remotely in use today, it is possible that using robotic help, the lava tubes could be explored and sealed effectively with current technology. But the fuel issue still remains.
    A space tether anchored to the lunar surface would be the most economical way to deal with takeoff/landing and cargo – at least it seems to be the most viable with no atmosphere on the moon. The space station would be the centripetal force to maintain line tension, and then solar powered lifting mechanism to get the loads up and frictional braking for the down.
    I do like these space posts…

  3. Oilman2 says:

    And that was a great book by Heinlein.
    Everything has a moving cost in reaction mass where rockets are concerned. In space, TANSTAAFL…right?

  4. mike says:

    Sounds feasible to me. But I suspect they will continue with the lunar station to use as an outpost for further exploration before committing.
    Years ago I hiked the lava tubes in the Washington Cascades south of Mt Saint Helens. The longest (~2.5km) is called the Ape Cave, no idea why, but I guess because you need to be part rock ape to navigate the rockfalls. Definitely not a smooth-walled hollow cylinder that the term ‘tube’ implies.
    Haven’t read Heinlein for fifty years or so. I need to re-acquaint myself with his works. With Kim Jong-un and Trump both ranting about death and destruction perhaps we all need to re-read Farnham’s Freehold.

  5. Laura says:

    Wow…love these images and possibilities. Heinlein expands the mind and the soul. Thanks for sharing.

  6. JJackson says:

    I also thought a lunar space elevator sounded much more do-able but I did a quick search and there is something called the Liftport group that have been looking at this for some years but I think the weak link is the their tether which is 250,000km long. Until material science can get carbon fibre or, something better, production on this kind of scale I don’t see it as being feasible in the short/medium term.

  7. JJackson says:

    This is a youtube link to an explanation of Liftport’s lunar elevator design.

  8. Fred says:

    Sounds like a much better idea than going to Mars.

  9. turcopolier says:

    the concepts are no mutuall exclusive. pl

  10. gemini33 says:

    Better scenery from the space station 🙂

  11. tpinlb says:

    One of the principal attractions of a lunar colony is the prospect of mining Helium-3 to fuel advanced fusion reactions that do not generate high energy neutrons and thus would not make the fusion machine parts radioactive. China has specifically targeted He-3 mining as a goal for a lunar colony. See Mining the Moon.

  12. BabelFish says:

    The ticket for launching cargoes, etc. around the solar system is the mass driver. Here is the Wiki on it. And the lava tube concept will probably be needed for Mars living as well.

  13. b says:

    Sorry to bust the party 🙁
    Pat says: “This Purdue University study tells us that large, long, voids exist below the surface of Luna.”
    No. The piece says “Purdue team found that if lunar lava tubes…”
    “If” … and later “In theory …”
    Volcanic activity on the moon is very different from the earth. There are no tectonic plates and we do not know how eruptions on the moon happened (if at all). It is also very old, mostly 3-4 billion years, and is thought to have ended at least 1 billion years ago. For that and various other reasons the chance to find intact “huge lava tubes” is extremely small. A number of seismic tests have been made on the moons surface. They found now signs of subterranean lacunae.
    The chances are too small to justify spending money on finding such highly hypothetical “lava tubes”. Simply building subterranean structures from scratch, if only a few feet deep, is likely way cheaper.
    One should also think of reusing the massive structures that will be needed to haul lots of stuff to the moon. Those structures could be best used for housing. Lots of people on earth live in shipping containers. Same idea.

  14. charly says:

    Lunar orbit is outside the protection of earths magnetosphere. You can test if people can survive in that environment while still being close enough to get back quickly. You want to know this if you are going to mars. Other use is remote control robots on the moon. From the Earth it takes to long (a few seconds) to control robots on the moon directly. You could also do that by landing on the moon but that cost much more.

  15. turcopolier says:

    I had an American colleague at WP who taught German. He had a “live in” mother-in-law who was from Berlin. He was a nitpicker like you. She referred to him as a “doppelsheisser.” I probably got the spelling wrong. She also called him “ein Albanischer garten zwerg.” She was right on both counts. pl

  16. turcopolier says:

    “Mass Drivers,” or “Rail Guns.” These are the same things to me. pl

  17. A Pols says:

    Energy required to get to the Moon and attain orbit is one thing and breaking lunar orbit to return to Earth is nominal. The Apollo capsule could have done a lunar orbit with a much smaller rocket than the Saturn, but the command module, descent module (half of which was left on the surface) and all their fuel made the needed payload from Earth to Moon much larger and the command module could have been smaller and lighter if it hadn’t needed all the extra juice to haul the descent/ascent stuff along.
    But adding the requirements of dropping from orbit to the lunar surface and then doing the whole thing in reverse raises the energy budget by a large amount and when you start considering the amount of material needed to build a surface or subsurface base, then all that gets multiplied. Not only that but a lot of that material ends up as scrap metal on the surface. So a Lunar orbiting station would be far easier to do, could even be done by modifying existing heavy lift boosters, while hoisting the requirements for building a surface base would be much harder to do. I’m curious as to whether anyone on this board can run the numbers for one versus the other.

  18. mongo says:

    Hello Sir,
    It’s possible that such natural features exist. The challenge would be in figuring out how to survey the Moon to determine where they are, and once identified, how to build sealed structures inside of them. Nothing insurmountable but it would take time and require that space station until they were habitable.

  19. Joe100 says:

    I was quite surpassed to read several months back in Sky and Telescope that there are mountains at the moon’s south pole that are always in sunlight. Their temperature is similar to some cold (but settled) parts of the arctic and it is known that nearby crater floors are always dark and contain significant water ice. So there is nearly habitable temperature, 24/365 sun for PV and nearby water to use to produce hydrogen fuel.
    Not sure what else matters, but these conditions seem like a good target for an initial lunar settlement.

  20. voislav says:

    Not a theory anymore, the discovery has been confirmed. 30 miles long, about 100 meters wide. Interesting challenge from an urban planning perspective.

  21. Peter in Toronto says:

    If the conspiracy theorists are to be believed, we were warned not to return to the Moon, and thus the premature cancellation of the Apollo program..

  22. LeaNder says:

    Dippelschisser/Dipfelescheißer(southern) = literal translation would be: someone who shits little dots.
    There may be other variants. These two come to mind.
    Anyway, the compulsive habit to add something that everybody else considers as superfluous as adding the “dot” over an “i”.
    Like this, urban dictionary:
    Nitpickery: The high crime of excessive, minute, and unusually unwarranted criticism.

  23. BabelFish says:

    Pat, yes. Rail gun is the newer term but they are technically identical as far as I know. I like the mass driver term as it reflects the science fiction I read when I was younger and sounds more elegant, IMO.

  24. David says:

    Science fiction writer Charlie Stross predicts that if there are no big
    delays in getting both the Dragon 2 and Falcon Heavy ready, then expect a
    circumlunar flight on July 19, 2019 (anniversary of Apollo 11). I wonder
    if maybe there would be enough time to have such a flight by December 25, 2018 is possible (anniversary of Apollo 8).

  25. charly says:

    We know that vulcanism existed on the moon. Some parts of the moon are much younger (still 3.5 billion years) than others and lava tubes are formed when the top of a lave river cools to stone and subsequently the lave in the river flows away. On the moon this is a very likely process. Those tubes are also very close to the surface so not finding them in a seismic test isn’t unexpected. Besides they are huge for a lava tube but on a planetary scale they are tiny. The tubes are also not highly hypothetical. second picture in this article is likely a skylight and the information to find those lava tubes are already gathered when they measure the gravitational field of the moon. Also on the moon to get the same protection against cosmic radiation you need about 10 feet of regolith. A tube has that already so if you find a tube with a skylight you don’t have to add cosmic radiation protection to your “shipping containers” Just place them 100 meters inside the tube

  26. Oilman2 says:

    @ jjackson…
    I think that the length of the tether and its strength would be much lower than people envision, IF they did not always do things in a hurry. The stresses are related to acceleration and mass, both of which can be managed. There is no reason that we couldn’t use multiple steel cables, other than mass and associated lifting cost.
    I think the anchor might be more problematic in regolith, as well as setting it in 0g.

  27. turcopolier says:

    I really liked the old gal. Phonetically it sounded like dippelshisser to me. it fit this guy perfectly. He could teach seven languages and had little to say in any of them. OTOH he had a beautiful singing voice. pl

  28. Oilman2 says:

    @ b…
    b, you need to stop blowing everything up with “facts” – it’s just a thought exercise.
    NOBODY knows what subsurface luna is – there could be aliens in lava tubes watching us via periscope – at this point, nobody can disprove that. They communicate with directed laser bursts so we don’t get any radio signals. They have matter converters like on Star Trek for food. They lay eggs on Earth that hatch every 10000 years, and that’s why they have the lunar watch station…
    The fun thing is, disproving those things is as difficult as proving them.
    And before you laugh, less than 1000 years ago, EVERYONE knew the Earth was flat!

  29. Donald says:

    I was hoping the ape cave name was a Bigfoot reference, but according to this link it is named after some group of mere humans who called themselves that and explored the cave. Darn.
    Lots of Bigfoot stories from that part of the country, as I remember reading as a kid, but this cave isn’t part of the lore.

  30. Martin Oline says:

    Here is a rail gun or “kinetic projectile” video. Unfortunately, they tend to destroy themselves with a few shots. I suppose an environment with little gravity might change the situation.

  31. Donald says:

    Darn it, I liked your post until the last sentence and now I am going to act like one of those German nitpickers. The ancient Greeks knew the earth was round and Eratosthenes probably made a pretty good estimate of its size— 250,000 stadia, but we don’t know exactly how big a stadia was. Hipparchus and Aristarchus made decent estimates of the moon’ s distance. The ancient Greeks were no dummies and people in the Middle Ages hadn’t forgotten what the Greeks had figured out.

  32. Babak Makkinejad says:

    That would be a sheep then.

  33. Linda says:

    What fun

  34. ked says:

    I support a space exploration model that establishes the systems capability to explore & settle space independently of planets (including Earth), moons & astroids… to transit even light years without having to land anywhere – our crafts will be our worlds. In this model, colonization of natural objects along the way is likely, while mankind’s chance of survival far & wide is enhanced. A robust extention of humanity that provides connectivity via self-sustaining ship-worlds. For Heinlein enthusiasts, think Orphans of the Sky.

  35. mike says:

    Donald –
    Thanks for that link. But perhaps you were right in the first place. The group that the link pointed out that first explored the cave that called themselves the Mount Saint Helens Apes – I’m thinking maybe they named themselves that because of bigfoot lore.

  36. Peter AU says:

    Mining Helium 3 will most likely come in time. But who will do it? A few nations are interested, US, China, Russia. US has managed a lot of showy stuff – sending man to the moon, space shuttle ect. But it is 1960’s designed Soyez that ferries astranauts to the ISS. It is soviet designed rocket engines that put US military satellites into orbit.
    A pity the US is doing its McCarthy thing at the moment. The combined resources and knowhow of the three countries combined could take space exploration a lot further.

  37. LeaNder says:

    Yes, correct, Pat, the German “sch” is mostly pronounced like the English “sh”:
    In this case, “sch” is a trigraph (a triplet of letters representing a single sound) and pronounced exactly like English “sh.”
    Easy to image a couple of scenarios. …

  38. earlthepearl says:

    In the Moon is a Harsh Mistress they mined ice to grow wheat. The wheat was sent to earth. It makes no sense because if they could grow wheat in caves on luna they could have just grown it in caves on earth.

  39. Oilman2 says:

    @ Donald…
    LOLOL – 276-195BC? Now didn’t I say the last thousand years?? So you are picking at your own nits Big D, not mine, and by an additional thousand years! You know dang well I was just trying to illustrate a point in very broad terms anyway.
    But I do enjoy when the Colonel tosses out these little thinking and extrapolating exercises…

  40. Babak Makkinejad says:

    I think you are not going far enough in confining yourself to the Solar System.
    What is urgently needed is the invention of a mechanism to enable mass migration from Earth.
    Currently, the situation on Earth is akin to a prison in which various gangs of prisoners are led by ruthless and viscous leaders who offer them protection at a certain cost.
    Every one loathes everyone else and constant fighting and murder – even over otherwise trivial items – are rampant.
    And everyone wishes to be out of that prison to resume his life and pursue his own happiness in liberty – never mind the fact that many would not be able to handle that liberty and freedom.
    I envision devoting 5% of world’s economic output to perform such research. In the ripeness of time, when such a mechanism is discovered and invented and put into practice, extant nations, minorities of all kinds, etc. would be free to emigrate to a suitable Earth-like planet or planets.
    The mechanism itself could be based on warp drive, worm-hole, faster-than-light travel of some as yet undiscovered feature or property of the universe.
    For example, Jews can move to a planet without a single gentile – thus putting to rest the fear of homicidal anti-Semitic gentile.
    Euro-American Protestant can move to one such planet called “America II” – where there are no Catholics, Jews, Muslims, Blacks, Armenians, etc.
    There would be a few desert-like planets in which a large number of Muslims – Shia or Sunni – could elect to live in tents and thus live their lives in a “Pure Muslim Manner”.
    The new inhabited worlds Karnatak, Tamil, and Lanka can exist in splendid isolation from one another – never having to come across a member belonging to that loathed “Other” subgroup.
    And needless to say, there would be a large number of planets solely for Kurds – since each valley will have to have its own planet. Like wise for much of sub-Saharan Africa.
    In this manner, we could hope that planet Earth could be left inhabited by those who are brave, enlightened, generous in mind and in spirit while all those who crave the security of a parochial existence could rejoice in their newly established but dead-ended colonial existences.

  41. charly says:

    The energy problem is likely solved before He3 will be mined on the moon so i don’t really see the economics behind He3 mining.

  42. charly says:

    Finding carbon is also a big problem on the moon. But ice you will find on the moon is probably a mixture of water and carbohydrates.

  43. charly says:

    I don’t know about the other groups but Euro-American Protestantism has a habit to split up with a big fight. You wouldn’t need 1 America II but a million. That is probably true f every other group too.

  44. JJackson says:

    Babak it sounds like a great recipe for inter-planetary war. Planet capitalist vs planet communist etc. Until we can get a recipe for living together on this planet it may be best not to inflict humanity on anymore of the universe. If ET is out there and watching us they probably view us much like Trump watching NK at some point they will decide we are too irrational and dangerous to be allowed out of our own solar system and will send in the Vogons.

  45. different clue says:

    Peter in Toronto,
    The particular variant of that theory I read is that ETs who witnessed our moon landing from a nearby lunar base were the ones to tell us not to return. Is this the particular variant of the theory to which you refer?

  46. different clue says:

    As to why a space station around the moon instead of directly on or in the moon, it may be that the Space Powers are treating this as a step-by-step learning-through-doing excercise.
    Since we know that we know how to do Space Station, we put a knowable Space Station orbiting around the moon so that we can practice and learn getting from earth to Lunar Space Station and back over and over.
    Once we know that, then we can work on learning to colonize the moon’s surface and/or interior with the Lunar Space Station right there to support the learning or to flee back to very fast if things go wrong for the learners and developers on or in the moon.

  47. Babak Makkinejad says:

    Nah, you just need to make the coordinates obfuscated and unrecoverable.

  48. Babak Makkinejad says:

    There are plenty of Earth-like planets out there. Sufficient for everyone.

  49. JJackson says:

    I don’t see a problem in anchoring into rock but the tensile strength of the tether is not the only problem. Having seen the damage accrued, on solar panels on our existing satellites, it would also need the bulk to sustain damage. The low lunar gravity means the lunar GEO is at 55,000km and the counter mass must be beyond this and a function of mass*distance which makes the tether very long unless you add a propulsion system (presumably solar powered) at the end of the tether to add tension. If the tether could be made of polymer that could be ‘painted on’ in place then the cargo carrier could include a repair mechanism to resurface/repair micro meteorite damage as it goes.

  50. JJackson says:

    An after thought.
    What we need is a giant space spider. This would be taken out to the Lagrange Point. It would need two spinnerets one facing the moon and the other earth. The spinnerets would extrude the the two tethers and the two bodies gravities would extend the threads in opposite direction. The rate of extrusion could be balanced to maintain station. Now all we need is one of the sites chemists to come up with a ways to spin a carbon fibre hawser from binary liquids which can be shuttled up from earth as required.

  51. Martin Oline says:

    Well, it looked good on the drawing board. The Navy is scrapping it’s $500mn rail gun. Link from RT which contains a link to Popular Mechanics:

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