Giant Lava Tubes Possible On the Moon

schwit1 writes: New analysis of lunar geology combined with gravity data from GRAIL suggests the Moon could harbor lava tubes several miles wide. "David Blair, 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. 'We 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,' Blair said. '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. In theory, huge lava tubes – big enough to easily house a city – could be structurally sound on the moon.'" You can read their paper here (PDF). If this is so, then the possibility of huge colonies on the Moon increases significantly, as it will be much easier to build these colonies inside such lava tubes.

Comments

First

[Anonymous Coward]

Outpost

Not a new idea

[nefus]

I don't think this is a new idea. If I recall correctly, it's come up in science fiction over the decades based on a variety of theories.

Re:Not a new idea

[Anonymous Coward]

"The Moon Is a Harsh Mistress." Robert Heinlein, 1966.

Re:Not a new idea

[Anonymous Coward]

"The Moon Is a Harsh Mistress," Robert Heinlein, 1966.

Re:Not a new idea

[Jhon]

Same author -- The Menace from Earth (1957).

Not sure if it were "lava tubes" (it's probably been over 30 years since I read that), but the idea of giant caverns being possible due to low gravity + high atm pressure was sure there.

Re:Not a new idea

[Jhon]

Wow. This internets thing is cool.

From Menace:

"Most of the stuff written about Bats' Cave gives a wrong impression. It's the air storage tank for the city, just like all the colonies have - the place where the scavenger pumps, deep down, deliver the air until it's needed. We just happen to be lucky enough to have one big enough to fly in. But it never was built, or anything like that; it's just a big volcanic bubble, two miles across, and if it had broken through, way back when, it would have been a crater."

Re:Not a new idea

[Dr. Zim]

They're not claiming it's a new idea, they're saying that such tubes are structurally sound for the purpose.

Re:Not a new idea

[hey!]

Sure, and sci fi has had anti-gravity for many decades, but I'm pretty sure that information suggesting it was actually possible would still be news.

Re:Not a new idea

[Anonymous Coward]

"The Moon Is a Harsh Mistress." Robert Heinlein, 1966.

And my personal sequel "I Can Lay A Lot of Pipe"!

Re:Not a new idea

[eric_harris_76]

I don't recall tubes, but it's been a while. I do recall at least one dome (which I took to be a bubble in the rock), big enough to house offices and maybe a public space of "town square" size.

And ice pockets big enough to mine. That one, I figured was just invented to make the story work and/or wishful thinking.

Re:Not a new idea

[nefus]

While many certainly could have been wishful thinking, if you consider the number of inventions created by science fiction writers then the odds are good somebody put a lot of thought into reasoning out why tubes might be there and how they could be used.

Re:Not a new idea

[RockDoctor]

it's just a big volcanic bubble, two miles across, and if it had broken through, way back when, it would have been a crater."

So ... Heinlein was writing within the accepted science of his day (no surprise there), which was that the craters of the Moon (there were no others known) were primarily a volcanic phenomenon.

In the 1960s there was a protracted dispute between various people in the geology community on determining the origin of the lunar craters. Eventually it was won by the people proposing that they were primarily impact-formed structures, and they did it largely by fieldwork on Earth examining various large terrestrial crater remnants. You may have heard of one of the proponents - one (Eu-)Gene Shoemaker.

Not detracting from Heinlein's fun storytelling, but his science was wrong. Which is an all-too-common problem when SF authors try to stay near the bleeding edge of science.

With the evidence from Apollo, and more recently from Lunar meteorites, we now know that most of the Moon's surface is composed of impact debris, with volcanic rocks in relatively restricted, dark areas known as maria.

Re:Not a new idea

[Jhon]

"So ... Heinlein was writing within the accepted science of his day (no surprise there), which was that the craters of the Moon (there were no others known) were primarily a volcanic phenomenon. "

I'm missing what you are trying to say -- is it that there were no volcanoes on the moon? Ever? If so, I believe you are wrong. Check out volcanic glass recovered by Apollo 17 and more recent papers on fairly RECENT volcanic flows (as early as 100 million years ago).

Besides, by the 1950's, I believe it was generally accepted that lunar craters were primarily (though not exclusively) the result of impacts. I believe a geologist named Gilbert first proposed the strongest argument for this in the 19th century.

I'm unsure how you can say "his science was wrong" about Heinlein. I wouldn't say he "got it right" as he didn't INVENT the idea of lunar volcanism -- but he wrote about using underground caverns in the 1950's in a way being described in the original article.

Re:Not a new idea

[RockDoctor]

Gilbert may have proposed that lunar craters were impact structures a long time ago (I'm tired of fighting with 20-minute page loads so I'm not going to search for it. I wish the crane operator hadn't smacked the aft satellite dish.), but that doesn't mean that his explanation was accepted at the time. As I said, the strong consensus at the time that Heinlein was writing (that book) was the lunar craters were volcanic phenomena. About 1962-63, an aspirant astronaut and field geologist, Eugene Shoemaker, started publishing and presenting papers arguing parallels between the structure of the small number of known terrestrial impact craters and the structures visible on the moon, and proposing that the large majority of the craters on the Moon were of an impact origin, not an eruptive origin. Through the 1960s Shoemaker argued the position, was ruled out of the astronaut corps for health reasons, and successfully changed the expectation until the Russian landers of the mid-60s shifted the balance of evidence appreciably in the favour of the impact origin hypothesis for craters.

Actually that's how science is meant to work. It wasn't as dramatic a paradigm change as the contemporaneous development and acceptance of plate tectonics and so was probably overshadowed in the popular press, but that is what went on.

Meanwhile, absolutely no-one has ever argued that all craters on the Moon are of impact origin and none of volcanic origin, in the same way that no-one has (TTBOMK, and I am actually a geologist) seriously argued that all terrestrial craters are of volcanic origin and none of impact origin. We know of craters and other structures on both bodies, of both origins.

Lunar rilles were proposed as possible lava tube collapses so long ago that I'd have to seriously look it up to find an alternative proposal (and that bloody crane operator!).

more recent papers on fairly RECENT volcanic flows (as early as 100 million years ago).

In the 1950s a variety of people (including the selenographer Patrick Moore, famous as a BBC astronomy broadcaster from the same period) were continuing to report "Transient Lunar Phenomena" from a number of places, and proposing that they might be the product of volcanic fumarole activity, or something similar. i.e. contemporaneous volcanic activity. Certainly not impossible, though it's not clear that Moore had really made his case. But he did present a good argument.

All that said, the overwhelming majority of the Moon's volcanic activity took place in the "maria-forming" period of about 4 gigayears ago (maybe as recently as 3.7 gigayears ago), and the structures formed then have only been lightly modified since. That is when the structures we recognise as "the Man in the Moon" were formed.

Check out volcanic glass recovered by Apollo 17

You seem to be under the misapprehension that volcanic glasses are of necessity "recent" (if not "Recent", or Holocene). This is incorrect. It is true that, under terrestrial conditions, volcanic glasses do devitrify fairly rapidly (I've sketched the thin sections ; I've actually used devitrification of (non-volcanic) glasses to estimate pressure-temperature conditions of a geological event as part of my mapping-derived Honours thesis. But I'll stress again that this is under terrestrial conditions. If you have a glass-forming melt which is very low in water, (and other volatiles, but principally water) then the devitrification rate goes through the floor as the mobility of ions in the glass drops considerably. By the time you're down to the millimolar (IIRC - marginal internet here, as I said above) water concentrations in your magma, it's perfectly possible to have glasses persist for billions of years. Your Apollo volcanic glasses could easily be Archean or Hadean in age (Before 2.5 gigayears ago, or 4.0 Gyr respectively : I've got Gradstein & Ogg's 2013 chart taped to the wall of the office.), and still be vitreous.

Heinlein's writin

Re:Not a new idea

[Jhon]

"Meanwhile, absolutely no-one has ever argued that all craters on the Moon are of impact origin and none of volcanic origin, in the same way that no-one has (TTBOMK, and I am actually a geologist) seriously argued that all terrestrial craters are of volcanic origin and none of impact origin. We know of craters and other structures on both bodies, of both origins."

Then you failed to indicate how his "science is wrong". A volcanic cavern or tube formed a few billion years ago or 20k years ago wouldn't really make a difference on usability if it remained untouched/undamaged, would it?

You seem to be under the misapprehension that volcanic glasses are of necessity "recent" (if not "Recent", or Holocene).

I was under no impression about "recent" activity -- just that it *did* occur. Your original post seemed to dismiss lunar volcanism having any meaningful role. Your most recent post clarified what you intended.

As for recent activity, I recall a few papers (i'm not a geologist but I have wide interests and a useless superpower -- I can read wicked fast) discussing flows as early as 100 million years ago.

http://lroc.sese.asu.edu/posts...

Heinlein's writing in the 1960s was based on the (incorrectly) accepted science of the 1950s.

That general statement is essentially true for all SF writers in any time -- but when the science *IS* right and they have insight they can describe a utility that may not be realized for decades -- or even centuries. I believe with regards to the utility of volcanic caverns, Heinlein's insight is most definitely correct.

"lava tubes"

[rogoshen1]

What he really means are giant lunar worms (ala Herbert). Just you wait, the first lunar colony will be smashed to bits by lunar death worms defending their ancestral homes from pesky, tiny intruders.

Re:"lava tubes"

[zlives]

can't wait for the lunar spice

Re:"lava tubes"

[sconeu]

I think what he really means is that Luna already has the internet. The tubes are there.

Re:"lava tubes"

[Bob_Who]

What he really means are giant lunar worms (ala Herbert)....

Lunar Worms? Don't forget about the Lunar ticks.....

Re:"lava tubes"

[An ominous Cow art]

My first thought was the moon worms from Major Matt Mason stories/toys of the late 60s/early 70s.

Ah, ok:

There was also a Big Little Book, Moon Mission written by George S Elrick and illustrated by Dan Spiegle published in 1968 that had the astronaut and his friends confront both giant rabbits and huge burrowing worms on the moon.

I had the book and a couple of the astronaut toys. I didn't remember the rabbits until reading this...

War on moons

[Anonymous Coward]

“We have the technology. The time is now. Science can wait no longer. Children are our future. American can, should, must and will blow up the moon.”

Re:War on moons

[Anonymous Coward]

Physics says it's easier to launch nukes at the Earth from the Moon rather than the other way around. Economics says it will take a long time for physics to catch up to reality.

Re:War on moons

[Tipa]

Why blow up the moon when there's so much stuff to blow up here on Earth?

Re:War on moons

[fyngyrz]

Blowing up the moon would be a highly efficient way to blow up stuff on earth. Assuming only random distribution of the resulting fragments.

Re:War on moons

[blue9steel]

To fight terrorism of course.

Re:War on moons

[Immerman]

That would have to be one hell of an explosion - not only would it have to shatter the moon, it would have to impart enough energy to the pieces to completely escape its gravitational well - less than that and the pieces would either re-coalesce or form a ring system in the Moon's orbit, depending on just how much less.

Even a truly massive explosion wouldn't be nearly as damaging to Earth as you might imagine - the Earth, as viewed from the moon, subtends only 1.2 milli-steradians, out of the total 4pi, so assuming a random distribution only about 0.00955% of the ejected material would be on a straight-line path to Earth, plus a little more whose path is sufficiently deflected by Earth's gravity to impact - everything else would either enter an elliptical Earth orbit or, if the explosion were large enough, escape the Earth's gravity as well and sail into interplanetary space (though of course many of their orbits around the sun would cross Earth's and eventually a collision would likely occur, so the next few millenia could be a little exciting). Though of course if it didn't escape the Earth we'd probably have to deal with some long-term bombardment as fragments collided and occasionally lost sufficient angular momentum to fall from orbit. Most though would probably eventually stabilize into a ring system.

Granted, the Moon is 7x10^22kg, so even 0.01% hitting Earth would amount to orbital bombardment by 7e18 kg, more than enough to do serious damage, even if it were so pulverized that it completely burnt up in the atmosphere. Still, you have to consider that the original explosion was enough to accelerate all 7x10^22 kg worth of fragments to at least 2.4 km/s (lunar escape velocity, or 2.88MJ/kg) so that they didn't fall back under mutual attraction, and all of that first 2.88MJ/kg of kinetic energy would be neutralized by the escape. Meanwhile, the specific orbital energy of the Moon relative to Earth's surface is only ~62MJ/k, so even if 100% of the Moon fragments hit the Earth you'd only get a 124x amplification factor, and if you factor in a more realistic .01% collision rate we're talking about only 1% of the initial explosion energy reaching Earth. And if the initial explosion imparted more than 2.88MJ/kg to the fragments, then you'd only get the 0.01% return on that excess energy.

All in all, you'd do far more damage to the Earth using the same amount of explosives here, rather than 400,000km away. And that's my dose of recreational physics for the day.

Re:War on moons

[fyngyrz]

So, like I said. Blow up the moon, and it'll blow up a lot of stuff on earth.

I didn't say it would blow up the earth.

I didn't specify how big an explosion, other than "blow up the moon", quoting the GP, which is going to be in the darned large side just to begin with.

As for your gravity fall back idea, when the moon is fragmented, the chunks near the surface are furthest from the others, which are all further from each other, so total gravitational pull is much less, plus, any leading elements are probably moving with maximum velocity -- nothing was in their way to bang into -- and so doubly likely to escape the gravity of the remaining cloud of fragments -- the larger that cloud is, the less pull on the outer edges of the cloud will be, because the mass that CAUSED that pull/warp is moving away in all directions. It's not the same math as trying to get "a rock" off "the moon" by any means. While in the meantime, the earth's pull, sufficient to keep the whole thing as a whole in orbit at its current orbital velocity, has not diminished, and so any fragments that are coming towards the earth afterwards, hence being pulled harder, are quite likely to be pulled out of the original orbit into impact trajectories.

And just ONE fragment of the moon about the size of Long Island landing here, m. physics person, would pretty much put a period to everything you know in fairly short order. Or, on other words, what I said in the first place. Blow up stuff on earth

And that's my dose of anti-strawman for the day. :)

Re:War on moons

[Immerman]

Of course pieces of moon raining down on Earth would be devastating, my point is that it would be far *more* devastating if you simply unleashed the same amount of energy directly on the Earth instead.

As for the specific energy required to break up the moon - it would actually be even higher than that required to get a single rock off the surface. Everything on the surface has a certain gravitational potential energy which must be overcome to escape the gravity well, as you go deeper that energy requirement increases. The fact that you're moving other pieces away at the same time changes nothing - conservation of energy requires that that energy debt be paid in full to get the pieces to stay apart rather than falling back in on themselves, regardless of whether only a single rock is being launched, or the entire thing vaporized.

As for stuff being "pulled in to the Earth" - if it doesn't hit on the first pass, it's, for the most part, not going to hit. Neglecting the complicating factors of the rapidly dissipating gravitational well of the ex-moon, every frgment will, at the moment of ejection, be on an elliptical orbit around the center of the Earth. Some of those ellipses will intersect the Earth, in which case that fragment will collide on it's first pass, everything else will continue to orbit in that ellipse forever* - there's no resistance in space to slow things down so that the Earth can catch things on the next pass. And since the Earth is the primary, there's no "gravitational keyhole" games that can be played to fine-tune the orbit for future collisions, as can happen with asteroids orbitting the sun.

* of course that dissipating gravitational well *will* confound things - instead of one big well you have many small ones all in different, but intersecting orbits (every orbit will initially pass through the space previously occupied by the moon - conservation of momentum dictates that the center of mass of all the fragments remain unchanged after the explosion - just like a rocket ship: the center of mass of fuel+ship never moves). As those fragments gravitationally interact with each other they will tend to circularize and coalesce into a ring system, but in the process some fragments will lose too much angular momentum and fall to Earth, while others will get thrown out at velocities that will escape from the Earth altogether. But mostly anything that approaches the Earth will be on a near-miss trajectory, and will rapidly be deflected onto a safer trajectory after a few more orbits interacting with it's peers - just as comets and asteroids rarely hit the sun: as objects get closer their tangential velocity increases dramatically, making them far less responsive to the gravitational pull. The only way they can hit the Earth is if their orbit gets stretched into such a long, narrow ellipse that it intersects the Earth itself.

Re:War on moons

[eyenot]

Applying the same explosive force required to blow up the Moon to blowing up a portion of the Earth instead would only be "more devastating" if you are purely measuring devastation potential in terms of forces of impact or explosive forces.

Don't forget that by and large, the opinion of the Moon in its relationship with life on Earth is more or less "vital". We have no idea what would happen to our weather and atmosphere, our oceans and water tables, or our life cycles if the Moon were obliterated.

Re:War on moons

[Immerman]

You are grossly underestimating the energies involved. Oh goody, Google located someone else who's already done the math (https://answers.yahoo.com/question/index?qid=20090102113458AADvZ2j)

Their conclusion was that to destroy the moon (i.e. completely neutralize the gravitational potential energy lost to the accretion of mass) would require 1.2445 x 10^(29) Joules, or the equivalent of 592.6 billion Tsar Bomba fusion bombs (the largest nuclear bomb ever detonated, at ~54 megatons of TNT, with a total destruction radius of 35 kilometers = 3848 square km). Now the surface of the Earth (land and sea combined) is only 510 million square kilometers, so we're talking the energy equivalent of 1,162 Tsar Bombas being detonated on every square kilometer of the planet. Or for an even more personal feel - if you live in a moderate-density urban area with 1/5 acre lots, that's one bomb capable of totally destroying Paris and the entire surrounding urban area (or New York City, three times over), dropped on *every* *single* *house*.

Somehow I think life on Earth would have a much easier time adapting to a little orbital bombardment and not having a moon anymore.

Re:War on moons

[eyenot]

Well then. Unless your figures are wrong (who knows?) then I guess I stand corrected.

Moon Internet

[danbert8]

We could make a civilization within the series of tubes!

Re:Moon Internet

[Anonymous Coward]

Therefore the moon is... a network router?

Caves

[Rei]

Don't we already know that these exist?

Re:Caves

[Half-pint HAL]

This article is about the maximum possible stable lava tube dimensions, given the moon's environmental parameters.

Re:Caves

[Anonymous Coward]

No need to state the obvious. Your average /. readers are all so damned smart that all of the information follows naturally. We don't need some pimply-faced grad student recite to us basic civil engineering facts.

Re:Caves

[Half-pint HAL]

Civil engineering is analogue. /. readers don't understand analogue.

Re:Caves

[Anonymous Coward]

Everybody understands analogue.

After all, it was an excessively large anal log which killed Elvis.

Say Cheese

[ISoldat53]

So the moon is made of Swiss cheese.

Re:Say Cheese

[Himmy32]

Now Ken we all know that the moon is not made of green cheese. But what if it were made of barbeque spare ribs, would you eat it then?

The roof is caving in.

[Anonymous Coward]

Move to the moon and live in an underground lava tube. Sounds like a brilliant idea, Until the things collapse.

Re:The roof is caving in.

[zlives]

lunar gravity is your friend, also support structures.

Re:The roof is caving in.

[TWX]

The entire point of using a lava tube is that it is its own support structure. The trouble is that lava tube ceilings, at least on Earth, do have a habit of shedding material. There's a lava tube in the Coconino National Forest in northern Arizona that has had its share of ceiling collapses and other cave-ins (which is actually how it was discovered in the first place) so there's a certain degree of greater risk when going in. For short visits the odds of being injured from a collapse is small, but I'm sure that living there would be quite risky.

I guess it'll come down to finding out if any lava tubes actually do exist on the Moon, and if so, does the surrounding geology mean they're truly stable. Given the moon's history of bombardment I wonder how many would have been destroyed in the intervening millenia.

Re:The roof is caving in.

[Applehu Akbar]

I have hiked in that very tube (about a mile long). If you had to live in a lava tube, it would be both easy to reinforce with something like shotcrete, being close to and parallel with the surface, and easy to create new entrances. It would be ideal protection from radiation.

Re:The roof is caving in.

[TWX]

That one probably is easy to fix as it's small. The ones on the Moon that people are talking about are supposed to be stadium-sized though, which means reinforcing a void that large is significantly more complicated. We could truck rebar up to the mouth of the cave in Arizona and run hoses to pump in concrete there, but on the Moon there is no cement factory and attempting to send that much rebar up would be cost prohibitive, and that's before even looking at the actual construction labor aspect of reinforcing it.

Re:The roof is caving in.

[Applehu Akbar]

You wouldn't use Earthly gunite on the Moon, but something more like epoxied regolith over carbon fiber mesh. The principle is the same. The article cites the possibility of large lava tubes. If those exist, there will be smaller tubes that will be early candidates for reinforcement.

moonquakes

[eyenot]

I didnt see ay mention of moonquakes. Considering these are a real and verified occurrence and considering the considerable amount of energy they release as has been recorded, any prediction of the structural integrity of lava tubes in the moon that doesnt take moonquakes into account is likely to be wrong.

Re:moonquakes

[Anonymous Coward]

Any dickhead that predicts these things aren't structurally sounds after having there for billions of years is likely to be wrong.

Re:moonquakes

[zlives]

reinforcing living structures would be necessary. but my thought is that the tech we have for building in seismic regions should transfer to moon just as well. Granted we would need more long term data.

Re:moonquakes

[bored_engineer]

I didnt see ay mention of moonquakes.

Did you read the paper? They didn't model any seismic activity, nor did they model any confining stresses. As such, their:

failure values are slightly conservative (i.e. low in magnitude) in order to compensate for [their] not modeling other stress sources such as seismic shaking from meteorite bombardment.

The point of the exercise was to theoretically confirm that large lava tubes can exist because:

Recent in-depth analysis of lunar gravity data from the Gravity Recovery And Interior Laboratory (GRAIL) spacecraft has suggested the possibility of lava tubes on the Moon with diameters in excess of 1 km.

Re:moonquakes

[SecurityGuy]

You have it exactly backwards. We don't know that they're there at all. All the study claims is that it's possible for them to exist because gravity alone wouldn't collapse them. GP is right, there are other things that might collapse them. You're also sort of right. IF they exist after all this time, it's pretty darn certain they're structurally sound.

Do they exist, though? We don't know.

Re:moonquakes

[g0bshiTe]

It would go along way to explain the hollow moon theory. At least it's more believable.

Re:moonquakes

[Anonymous Coward]

Given the known existence of lunar rilles, which may well be collapsed lava tubes, it's pretty darn certain that some of them aren't (or rather, weren't) structurally sound.

That said, yeah, if they've lasted this long, odds are they'll last a good while longer.

Re:moonquakes

[TWX]

We do not know the effects of meteoric bombardment. Lava tubes that appear stable hundreds of kilometers from an impact might collapse even if the surface in that region would be otherwise unaffected.

Re:moonquakes

[Rei]

Um, yes we do know that they're there. There are plenty of pictures of skylight caveins and entirely collapsed tubes from satellites orbiting the moon. On Mars, too.

Re:moonquakes

[SecurityGuy]

We have pictures of 5000m wide lava tubes on the moon? Link, please? I never heard of that. Pretty cool if it's true.

Re:moonquakes

[eyenot]

All of the fools in this thread mentioning "meteorite bombardment" have not the foggiest. Moonquakes are a lot more powerful and a lot deeper than the faint tremors that would be caused by surface impacts.

But that's no surprise that people aren't interested in moonquakes or never heard of them before, even if they're lunar scientists. Even NASA didn't want to acknowledge their existence at first.

But look at them, now: http://science.nasa.gov/scienc...

The truth is that nobody is sure what causes the most powerful moonquakes.

Re:moonquakes

[RockDoctor]

The link is one of the references in TFA. IIRC, it was reference 3 or 4, but having downloaded, saved, opened and read the paper (abstract really), I see absolutely no reason to deny you that pleasure. Enjoy!

Re:moonquakes

[RockDoctor]

Considering these are a real and verified occurrence and considering the considerable amount of energy they release as has been recorded,

Have you actually looked at the magnitudes of moonquakes? Apart from the sporadic ones caused by impacts, they're not powerful quakes, and they're deep below the surface, which add up to low levels of ground shaking. Which is what you are really concerned with.

The typical shaking caused by a 5.5 magnitude earthquake (on the moment-magnitude scale, since the Richter scale has been deprecated since the equipment went out of service in the 1940s and 50s) would be in the region of V - VI on the Modified Mercalli Scale :

V. Moderate Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.
VI. Strong Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.

You're worrying about a pretty small hazard.

Stupid.

[Anonymous Coward]

There is no point in building large cities on the moon. Seriously, why? If you want to live underground, do it on Earth.

Anything like this on the Moon would be exceptionally dangerous to live in. The only people that should be on the moon would be the bare minimum necessary to man mining operations - that's IF we find anything on the moon worth mining that doesn't cost 100x what it's value is to get back to Earth.
You could make an argument that it would make sense to have some type of base on the moon to serve as a launching point for missions farther out, and that would be fine. If we can find anything farther out that is worth leaving behind our comfortable Earth for more ... um ... fatal climates.

Re:Stupid.

[Rei]

There's unlikely to be much in terms of heavy metal deposits, apart from asteroid finds, which doesn't sound like a market big enough to justify the expensive of the trip. Helium 3 is a total red herring. And of course your labor and hardware costs will be through the roof due to the incredible expense of shipping consumables. Isotopic Enrichment of light elements in-situ seems quite unlikely as a consequence.

Still, I can envision a market. Just any old moon rock will always have an interest from collectors who have an interest in space, and mineral collectors in general. You could probably turn a good profit on an ongoing basis for regular shipments of small volumes of samples to be sold at very high prices.

Any gemstone finds on the moon would have an additional, and much broader market, they could probably command incredible market prices. Most precious gems are made of light elements like one finds on the moon, and in processes that could readily have occurred on the moon. There probably are new gem species that never naturally occur on earth in sizeable quantities as well. A funny one would be if moonstone was found on the moon. (Na,K)AlSi3O8 and formed in plutonic felsic rock, all of the ingredients appear to be there. :)

Re:Stupid.

[surd1618]

There is no point in building large cities on the moon. Seriously, why? If you want to live underground, do it on Earth.

I want to be the founder of Moriah.

Re:Stupid.

[Anonymous Coward]

Good info if you're focusing on moon exports, but if we're talking about manned colonies, the stuff used locally is far more valuable. A US gallon of water is about 9 pounds, so considering transport costs, we're talking probably $100,000 per gallon to bring water to the Moon. Not having to launch and land that stuff is money in the bank, my friend. Even if it's not manned (e.g. a remote scientific research station), water is immensely useful as radiation shielding, processed into rocket fuel, etc. That's what most of the mining would be based around, working toward self-sufficiency.

Of course, it's way, way cheaper to not send people at all, but c'mon, won't somebody think of the science?

Re:Stupid.

[riverat1]

There is no point in building large cities on the moon. Seriously, why? If you want to live underground, do it on Earth.

I see the Moon as the gateway to the rest of the Solar System. It's a ready source of raw materials outside of Earth's gravity well but has enough gravity to keep things from floating around much which makes living there easier than in zero-G. Lack of atmosphere and low gravity make launching anything to orbit or beyond pretty easy. Setting up an interconnected series of solar power collectors around the equator would take care of power needs. The Moon may even have enough gravity to ameliorate the worst effects of zero-G on human health.

I think a top priority should be setting up a starter base that can start bootstrapping the rest of the needed infrastructure.

Re:Stupid.

[Immerman]

Granted, Helium-3 would be a challenge to mine, and we don't actually have any use for the stuff yet - that would be a more long-term resource. But Lunar soil is roughly 40% oxygen, which would be an extremely valuable resource on its own (for breath-gas and LOX-using rockets). And assuming a ready source of hydrogen and/or carbon can be found there's great potential to synthesize water and rocket fuel there as well. If nothing else it would potentially be a hell of a lot cheaper shipping just hydrogen from Earth and combining it with lunar oxygen to create water and peroxide-based fuels.

Re:Stupid.

[Immerman]

For starters, on Earth you have to deal with Earth governments, worry about Earth wars, and guard against Earth diseases. On the moon there would be potential for a fresh start - much the same motivation as moved most early Europeans to colonize the Americas. Granted it would take a far more rugged and visionary colonist to settle a dead rock than a lush continent, but so what? Perhaps the self-selection of visionaries and dreamers crazy enough to colonize the Moon would lend itself to forming a new kind of society. Worth a shot at least. It's not like the resources would be doing any more good on Earth - we've had the technology to turn the Earth into an Eden for everyone for a century at least, yet we insist on obsessing over the same damned selfish and short-sighted motives that have driven us since the dawn of civilization.

Diamonds?

[Bugler412]

Wonder if the lunar tubes would be diamond laden like on earth? Finance the building of lunar bases? Or just crash the "diamond economy"?

Re:Diamonds?

[MightyYar]

Yeah, a crash. Diamonds aren't really all that rare and can be manufactured. There might be some fashion value in "gemstones from space", if it can be proven that they are lunar in origin by some kind of analysis.

Re:Diamonds?

[Rei]

Very few volcanic pipes are diamond laden on Earth - primarily just kimberlites, which require a special type of volcano feed by very deep magma that's high in volatiles. They're almost all very old. The moon tends to be poor in volatiles and the depth requirements would be far greater to achieve the necessary pressures, at least 1/2 to 2/3rds of the way to the core.

Still, who bloody knows?

There's all sorts of gem possibilities on the moon, way too many to list here. They're probably the most valuable export-to-earth lunar resource we could mine at this point in time, as you can imagine what sort of premium the market would put on them even if they're pretty much the same as earth gems (let alone if they're mineral species not found on earth)

Re:Diamonds?

[Anonymous Coward]

Kimberlites pipes are not hollow; they are filled with rocks and they are usually vertical and very deep (and partially exposed by plate tectonics which does not exist on the moon). This discovery is of horizontal hollow pipes full of nothing, not even air.

Re:Diamonds?

[RockDoctor]

Actually, there's at least one kimberlite which erupted in the Eocene - up in central Canada, IIRC. Whether it is diamondiferous, and it's relations to the known-diamondiferous ones a little further north, I don't know.

When I was a student of mantle petrology (as opposed to earning a living grubbing around in the crustal ephemera), we couldn't say "there is no chance of a kimberlite being emplaced somewhere on Earth tomorrow. And I still don't see any particular reason to make such an assertion. And to be honest, I'd like to see it happen. Even with the boulders falling from the skies, raining death and destruction across the landscape, I'd like to see it. It'd be some sight to see.

David Weber

[irrational_design]

This reminds me of one of David Weber's book where the moon is really a giant spaceship with a thin layer of rock over the top to camouflage it. As I recall the original moon was dropped into the sun. Nobody noticed the switch since this happened long before humans were around.

Re:David Weber

[mhotchin]

'Dahak' trilogy. An OK read, but a bit frustrating since the story-line was abandoned - huge unresolved plot points.

Past is Present

[Anonymous Coward]

H.G. Wells was right

Low gravity (Re:Stupid.)

[mi]

There is no point in building large cities on the moon. Seriously, why? If you want to live underground, do it on Earth.

One use would be for retirement communities — the thought occurred to me some 10 or 15 years ago, but then read about it somewhere in Heinlein's writings.

The low gravity of Moon would allow the elderly (and other infirm) to remain mobile for many years after they would've become wheelchair-bound on Earth... Considering the wealth of (relatively) many of the elderly in the Western world, they may be able to pay for such retirement even before some other industries take hold up there.

Re:Low gravity (Re:Stupid.)

[Rei]

And would mean that earth-quality emergency medical care would be almost impossible to get.

Seriously, the last people you want to put onto a rocket and launch at several Gs up, into a high radiation environment, and then land on a desolate rock far from the rest of human society, is people who can die from hitting something too hard.

Re:Low gravity (Re:Stupid.)

[Anonymous Coward]

You think some grey hair hitting the gas pedal instead of the brake pedal and slamming into a storefront here on Earth is just a funny YouTube moment? Wait until they do it on the moon and smash through the tube wall and into a hard vacuum.

Re:Low gravity (Re:Stupid.)

[mi]

And would mean that earth-quality emergency medical care would be almost impossible to get.

Blah! Of course, well-qualified medical personnel would have to live on the moon with their (would-be) patients.

Seriously, the last people you want to put onto a rocket and launch at several Gs up, into a high radiation environment

The acceleration should be possible to overcome with well-designed equipment. Sure, some of the people may not be fit enough to reliable survive the travel, but enough of them will be able to do so once — and then enjoy many years of life after that.

people who can die from hitting something too hard.

Avoiding hitting something "too hard" will be much easier if the gravity is 1/5th of what you've struggled with your whole life...

Re:Low gravity (Re:Stupid.)

[Anonymous Coward]

So name a people who won't die from being hit too hard!

Re:Low gravity (Re:Stupid.)

[itzly]

The low gravity of Moon would allow the elderly (and other infirm) to remain mobile for many years after they would've become wheelchair-bound on Earth... Considering the wealth of (relatively) many of the elderly in the Western world, they may be able to pay for such retirement even before some other industries take hold up there.

Or we can stick them in a bed with VR goggles on.

Re:Low gravity (Re:Stupid.)

[Anonymous Coward]

As for the high radiation environment, that can be *less* of a problem for the elderly. The cells you don't want damaged are the actively dividing ones, i.e. in the young. Once you hit old age who cares if a gamete gets screwed up, and as for cancers associated w radiation most take many years to develop after exposure. That's one reason cited by a bunch of retired nuclear workers who volunteered to go back to work on Fukushima. If it takes a couple (or more) post-exposure decades to develop a dangerous cancer the best people to send would be able bodied 70 year olds. Odds are good it's not going to be a radiation induced cancer that kills them.

Re:Low gravity (Re:Stupid.)

[MondoGordo]

" is people who can die from hitting something too hard." Seriously? ... doesn't that include, well, everyone?

Re:Low gravity (Re:Stupid.)

[Anonymous Coward]

Dead people.

Re: Low gravity (Re:Stupid.)

[cinky]

And I mean come on, if I'm at the point where I need a wheelchair on earth... If I can choose I want to go out during a rocket launch (with a bang! KSP does that to you) rather than in a hospital bed.

Re:Low gravity (Re:Stupid.)

[MiniMike]

Wouldn't the elderly be better off on a space station? You could actually control the level of (artificial) gravity by designing it with rings and spinning the station (ref. almost every scifi story in space). They could start off at the outer layers (maybe 0.5 G equiv.?) and work their way up through the rings as their capabilities decreased. When they perish (dead ringers?) they could be released to fall back to Earth (shooting star), or on an orbit to intersect the Sun (if they need more flare) or wherever they chose.

Re:Low gravity (Re:Stupid.)

[ceoyoyo]

Actually, if you're going to stick someone into a high radiation environment, the older they are the better. It wouldn't be difficult to send good medical equipment and personnel along as well.

The people you sent would have to go while they were healthy enough to make the trip, but once they were there, they might enjoy a longer life than otherwise: low gravity lessens the risk of falls, but also eases the strain on the heart and circulatory system.

And the stream of centenarians dying would provide fertilizer for making lunar soil.

Re:Low gravity (Re:Stupid.)

[blue9steel]

And the stream of centenarians dying would provide fertilizer for making lunar soil.

That's both amusing and practical, I like it.

Re:Low gravity (Re:Stupid.)

[mi]

Wouldn't the elderly be better off on a space station?

I would think, constructing such a station would be orders of (decimal) magnitude more expensive and complicated, than building a habitat on the Moon.

Yes, your deliveries from Earth would be cheaper for such a station, but you are going to need a lot more delivered starting from scratch in empty space. And maintaining a constant spin is a non-trivial engineering task, whereas we already know just about everything required for building on the Moon.

Re:Low gravity (Re:Stupid.)

[dotancohen]

The low gravity of Moon would allow the elderly (and other infirm) to remain mobile for many years after they would've become wheelchair-bound on Earth.

In order to enjoy 0.3 g on the Moon, you need to suffer 3+g for a good ten minutes leaving Earth. I'm not sure that the elderly or infirm will stand for that.

The Saturn V's actually were one of the slowest-accelerating human-rated craft to ever launch, and they hit a peak of 40 m/s^2, about 4 g, at MECO 1:
http://history.nasa.gov/ap11fj...

Re:Low gravity (Re:Stupid.)

[miller701]

Fascinating link. I wonder how the Mercury and Gemini G curves look.

Re:Low gravity (Re:Stupid.)

[dotancohen]

Good question. According to this guy, both Mercury (no mention if Redstone or Atlas) and Gemini broke 7 g:
http://space.stackexchange.com...

I would imagine that the Gemini curves looked something like g = t + sin(t) as they had real pogo problems with the Titan rockets. If you find an actual graph, please post it!

Re:Low gravity (Re:Stupid.)

[Rei]

I would think, constructing such a station would be orders of (decimal) magnitude more expensive and complicated, than building a habitat on the Moon.

You would be wrong.

Re:Low gravity (Re:Stupid.)

[Anonymous Coward]

I'm more concerned of the constant flashing orange light seen from Earth, as one of the old bastards forgot to turn the left turn indicator off, again.

The Van Allen belts are an even harsher mistress

[Anonymous Coward]

Sure wish we knew how to get past 'em

dwarf fortress

[Anonymous Coward]

Just make sure they've labeled all the floodgates appropriately.

DF

[Anonymous Coward]

I'm pretty sure I did that in Dwarf Fortress already

Theoretically possible

[tomhath]

TFA concludes that really large domes might be possible.

Not that are any.

Not that they could be sealed and made habitable.

Just that in the Moon's gravity they *theoretically* might not collapse.

Re:Theoretically possible

[blue9steel]

Not that they could be sealed and made habitable.

Sealing them is pretty straightforward actually, you just use a sprayable plastic to coat to the interior. Combine that with a series of air pressure sensors throughout and a small maintenance crew and you're all set. Settling the moon isn't really a problem from an engineering perspective, the issue is economics. It's expensive to get there, it's expensive to live there and so far there isn't much we want there. The only real things that would make any sense at the moment are A) A military installation with a mass driver so that we could bombard terrestrial targets with kinetic impactors instead of nukes or B) He3 mining, which won't be useful until we develop Fusion (and only certain kinds). Given significant other space activity it might also be a useful source of raw materials available from a lower gravity well than Earth. Oh, the dark side would make an excellent astronomical observatory but that's a pretty expensive project for what you'd get out of it.

Re:Theoretically possible

[Immerman]

Tubes, not domes - somewhat different mechanism, and radically different shape and size. On Earth the theoretical limit of lava tube length is apparently 30-900km, depending on assumptions - that's one hell of a lot more enclosed area than the width would suggest. And on the moon we have discovered cave-ins 900m across, so that suggests that tubes at least roughly on that scale do exist.

And if tubes that large can theoretically exist, it seems reasonable to assume that much smaller stable tubes, say only a block or three across, probably do. (I tried to find information on the largest theoretical tubes on Earth to compare to the largest discovered, to no avail) And if they do, then further stabilization and sealing should be a relatively minor issue - the structural elements are already in place, you've just got to plug the holes. Break out the vacuum-grout (worst, case chink it by hand with rocks, or tough spray-foam in plastic bags) and then cover the lot in a tough air-impermeable surface (concrete? metal? plastic? nanocellulose?). After that habitability is pretty much assured, assuming there's enough rock over your head to protect you from cosmic rays and the like.

Hell, if you didn't want to do any new material-science work you could just inflate a large balloon within the tube, install a bunch of anchors through it into the surrounding stone, and throw on a few inches of sprayed concrete. Or don't bother sealing it at all, just build your little inflatable domes (or whatever) within them. The point is that you have stable radiation shielding already in place, and need only worry about retaining atmosphere and heat to enable long-term radiation-free outposts.

Re:Theoretically possible

[Coren22]

I cannot conceive of the amount of energy a mass driver would take. The moon is orbiting at 3,683 km/h, so you would have to slow a projectile by that much to hit the earth, and it would have to be very precisely aimed to hit a spot on the surface of the earth as it would take days to hit the Earth. The moon is a terrible place to put a kinetic weapon, but LEO isn't any better as you need to slow the projectile by 28,080 km/h to be able to hit the Earth, and be able to aim yet again.

This isn't just a matter of aiming something at the Earth and shooting it like a bullet, you have to reduce its orbital velocity or it will just float back up to the moon's orbit, or crash back to the moon if you don't shed orbital velocity.

Re:Theoretically possible

[blue9steel]

Pretty simple to slow down as long as you don't mind burning up part of your projectile during atmospheric braking, meteors do it all the time and the big ones make a nice crater. Earth based weapons are cheaper, the advantage of the Moon based one would be the difficulty in counter-battery fire. Obviously it wouldn't be very useful for moving targets due to the flight time but for anything that is stuck in place (cities, military bases, etc) it would work just fine. Refining your aim prior to real use would be easy as you could use projectiles small enough to burn up on re-entry to work up all your firing data. *shrug* It would likely be a bit of a boondoggle but the spin-off technologies and infrastructure buildup would be useful.

Re:Theoretically possible

[RockDoctor]

Sealing them is pretty straightforward actually, you just use a sprayable plastic to coat to the interior.

Hmmm, you sound like someone who has actually spent a lot of time installing materials over your head, supported on ropes of uncertain anchorage, or installing the scaffolding truss work to avoid having to trust the rock which you're trying to stabilize. Or rather, you sound like someone who hasn't done exactly that.

I'm not saying that it's not do-able. But that doesn't mean to say it's "straightforward".

Actually, I'd expect the process to work more by building initial bases in smaller tunnels and tunnel sections, then using the structural strength of those buildings to anchor extensions of the walls to surround increasing volumes. Kind of like the building of a cantilever bridge, if you get my drift. A pretty long term programme.

Re:Theoretically possible

[blue9steel]

I'm not saying that it's not do-able. But that doesn't mean to say it's "straightforward".

I was suggesting that it didn't require any new scientific discoveries and that our current technology could be adapted to the task. It's an engineering and construction problem certainly but not out of reach.

Re:Theoretically possible

[RockDoctor]

Neither does drilling a hole in the ground involve any new technology principles. Tell that to the widows of the Macondo 11. Or the Piper Alpha 167. Or the North Cormorant 13. Or the Shetland 45. Or the more recent Shetland 4. Or, for that matter, yesterday's Russian 54.

Moonbase-1 will be built on blood (boiled to a powder) and bones.

Re:Theoretically possible

[blue9steel]

Moonbase-1 will be built on blood (boiled to a powder) and bones.

And that makes it different how? Construction has always been dangerous business.

Re:Theoretically possible

[RockDoctor]

Construction has always been dangerous. That doesn't mean that the number of deaths is acceptable.

We actually had to give up an hour of our off-shift time last Sunday, after the safety meeting, to go through some corporate "culture building exercise" (something I normally associate with home brewing) about how in the past the death rate was reckoned at about one corpse per million dollars spent, but by the investment of 0.13 million dollars (a leg or so), the guy who constructed the Golden Gate Bridge saved 26 lives on his 35 million dollar project, and got something like a 800% ROI from his spending on safety.

Working in construction (of oil wells, but it's construction nonetheless), it is just possible that I take a slightly different view of "that makes it different how?" Those people you dismiss with a "how?" are friends and colleagues of mine. We're on a half-billion dollar work site trying to construct things that your (and my) civilisation is going to be needing and using in the coming decade. I'm probably a damned sight closer than you are to the man who'll be earning his dollar "spraying plastic onto the roof" of your Moonbase. It won't be constructed by geeks steering robots by telepresence. At the very least, speed-of-light means that it'll be constructed by telepresence from within Moonbase-0.5. Bollock-frying radiation, leaky vacuum toilet and monotonous dehydrated diet and all.

And on that subject - our internet connection dies for the 4th time in a half hour. What was I saying about telepresence?

Re:Theoretically possible

[blue9steel]

I've done construction, it's dangerous, backbreaking, often uncomfortable, thankless work, which is why even the entry level jobs pay more than serving fries at McDonalds. If we can find ways to make it safer I'm all for it. In the meantime we seem to have gotten seriously off topic.

Why live on the moon?

[Anonymous Coward]

It is a harsh mistress after all. There is nothing there that would be worth building settlements.

Oblig

[fyngyrz]

I. for one, welcome our... no, wait... imagine a beowolf cluster of... um... in Soviet lava tubes, er, the tubes... the intertubes... no, no... these tubes are like a car, see, in that they... they... ok, then, Netcraft confirms that these tubes... well, but BSD is definitely... Aw, futz. I'm memeless, you insensitive clods!

Re:Oblig

[Maow]

How about, "Hey, check out the lava tubes on the moon."

"Hey, that's no moon!"

"Heh heh, and that ain't a 'lava tube' either!"

NEW LANDFILL!!!

[Anonymous Coward]

Maybe we can dump our garbage in the lava tubes or stockpile nuclear waste! Gerry and Sylvia Anderson would approve.

The Moon is like a series of Tubes

[Virtucon]

The Moon is like a series of Tubes - If Ted Stevens had been an astronaut.

Re:The Van Allen belts are an even harsher mistres

[Immerman]

Quite. It's a damned shame the way Buzz Aldrin and his crew died screaming on live TV, and on what was to be such a historic Moon-landing mission too.

Gravity mapping

[Anonymous Coward]

I wonder if the gravity mapping techniques that earth-facing satalites are already using is sensitive enough to locate such lava tubes on the moon, if they do indeed exist?

Re:Gravity mapping

[ceoyoyo]

That's what GRAIL is, and yes, it's found signs of large lava tubes. So says the summary.

Could, if, in theory

[gatkinso]

These appear too many times in the article to take the idea seriously.

Sounds like a good DF embark...

[Anonymous Coward]

Personally, I'd like to embark on one of these magma tubes in Dwarf Fortress. It can't be that much harder to ensure fun on than a haunted glacier, though I will have to remember to bring extra Oxygen at embark....

So are giant mouse people living in the cheese

[Karmashock]

Tell me what we've found not what we might find.

Hadley Rille?

[MichaelSmith]

I thought it was a collapsed lava tube. The lunar surface is pretty heavily pounded so hollow tubes are fairly unlikely, at least accessible ones.

The Cave is Collapsing!

[BadPirate]

"This is no cave."

Would they form ?

[Anonymous Coward]

Volcanic Lava tubes form on Earth because the outer parts of a flow are cooled and the inner part flow away after the volcano stops producing lava. The cooling occurs relatively quickly because the air can carry the heat away, or water carries it away when the flow enters the sea.

On the moon there is no air or water and so the heat can only radiate away and that may be far too slow for tubes to form.

Coincidence

[andrewa]

This in the same week that The Clangers make a reappearance on English TV....

Mr. President!

[Latent Heat]

We must not allow a lunar lava-tube gap!

There you have it folks!

[Anonymous Coward]

"The Moon, Actually Exists!"