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."  Space.com

-------------

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 

https://www.space.com/28894-moon-lava-tubes-underground-cities.html

https://en.wikipedia.org/wiki/The_Moon_Is_a_Harsh_Mistress

Comments

[JJackson]

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.

[Oilman2]

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...

[Oilman2]

And that was a great book by Heinlein.

Everything has a moving cost in reaction mass where rockets are concerned. In space, TANSTAAFL...right?

[mike]

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.

[Laura]

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

[JJackson]

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.

[JJackson]

This is a youtube link to an explanation of Liftport's lunar elevator design. https://www.youtube.com/watch?v=R3gOS2e7m6Q

[Fred]

Sounds like a much better idea than going to Mars.

[turcopolier]

fred

the concepts are no mutuall exclusive. pl

[gemini33]

Better scenery from the space station :)

[tpinlb]

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. https://www.technologyreview.com/s/408558/mining-the-moon/

[BabelFish]

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.

https://en.m.wikipedia.org/wiki/Mass_driver

[b]

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.

[charly]

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.

[turcopolier]

b

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

[turcopolier]

Babelfish

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

[A Pols]

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.

[mongo]

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.

Regards,
mongo

[Joe100]

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.

[voislav]

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

http://www.asahi.com/ajw/articles/AJ201710180045.html

[Peter in Toronto]

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..

[LeaNder]

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.

[BabelFish]

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.

[David]

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).

[charly]

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 http://www.bbc.com/news/science-environment-31953052 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