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[mainiac]

The immense amount of silicon in there is bound to oxygen atoms in a very happy formation that it doesn't want to break out of.  Thus, you need a ton of energy to do anything with it.  Honestly, you're better off mining landfills than you are the moon.

Landfills aren't worth thousands of dollars a pound by virtue of their location.  Energy is a surmountable hurdle.  Energy can give you silicon can give you more energy.

[Eagleon]

Guys, keep in mind, the amount of surveying we've done on the moon amounts to chucking a spectroscope over Africa, dropping a couple of prospectors in one spot for a couple of days, and throwing some bricks at a half-acre in the Congo to see what kind of dirt it kicks up. That's it. We simply don't have a clue, in particular, about how extensive and concentrated deposits made from meteorites and comets are (dependent largely on impact speed, but almost certainly there for the taking in some craters), and what kind of deposits have been made due to the moon's formative geological changes. There definitely was a time when the moon underwent all kinds of activity, and that was after it impacted Earth and potentially plenty of time before.

It's very difficult to say for sure that a place uniformly covered in high-albedo dust is really as barren as it looks. For all we know, there could be huge bands of nickel-iron whipped up from the core very close to the surface, and a half-foot of dust and regolith would hide it as perfectly as if it wasn't there. It's probably not too likely, but given the time when the moon's structure was 'finalized', so to speak, I wouldn't be terribly surprised.

[Montague]

Guys, keep in mind, the amount of surveying we've done on the moon amounts to chucking a spectroscope over Africa, dropping a couple of prospectors in one spot for a couple of days, and throwing some bricks at a half-acre in the Congo to see what kind of dirt it kicks up. That's it. We simply don't have a clue, in particular, about how extensive and concentrated deposits made from meteorites and comets are (dependent largely on impact speed, but almost certainly there for the taking in some craters), and what kind of deposits have been made due to the moon's formative geological changes. There definitely was a time when the moon underwent all kinds of activity, and that was after it impacted Earth and potentially plenty of time before.

It's very difficult to say for sure that a place uniformly covered in high-albedo dust is really as barren as it looks. For all we know, there could be huge bands of nickel-iron whipped up from the core very close to the surface, and a half-foot of dust and regolith would hide it as perfectly as if it wasn't there. It's probably not too likely, but given the time when the moon's structure was 'finalized', so to speak, I wouldn't be terribly surprised.

Sorry, the moon simply is not going to be as interesting or diverse as Africa. There won't be the same types of geological processes on the moon as on the earth, specifically no sedimentary or metamorphic formations at all. The moon is literally a ball of molten iron-nickle and volcanic rock that solidified and stayed that way ever since. Iron in the inside, homogenous slag on the outside. We know what the moon is made out of and how it was formed. There has been very little change to it's geology except for whatever impacted the moon. So its a poor comparison to suggest the moon is something like Africa. It's more like as interesting as a geologically homogenous desert or mountain range.

That said, there are possibilities that astroid impacts and whatnot might have introduced something interesting to the surface, but that's probably an exception to the rule and such deposits are probably more iron-nickel or silicon dioxide rock like everything else.

Also, I'm really struggling to figure out why everyone is so excited about iron-nickle on the moon. Iron is already abundant here on earth, it's extremely cheap and iron mines and steelworks struggle to turn a profit. Or ice, for that matter. Ice is a dollar for a 10 lb bag, guys, it's not that big of a deal.

[Eagleon]

You're saying we know all the processes that occur when a massive body impacts another and then freezes without further significant tectonic activity? We know exactly what kind of transient geochemistry occurred during and after the impact event on Earth and the moon, and what the moon's volatiles did to its chemistry while they were still around? Wow, when did we discover all of these things? There's simply nothing like it to compare with on Earth, because the entire crust has been churned under and regurgitated by metamorphic processes. The processes we can examine on Earth, by comparison, are nowhere near as energetic, and influenced heavily by the resulting chemistry from billions of years of subduction, a process which didn't occur on the moon.

Nearly everything that we could have seen before, during, or immediately after the impact is gone now, except for on the moon.

[Montague]

You're saying we know all the processes that occur when a massive body impacts another and then freezes without further significant tectonic activity? We know exactly what kind of transient geochemistry occurred during and after the impact event on Earth and the moon, and what the moon's volatiles did to its chemistry while they were still around? Wow, when did we discover all of these things? There's simply nothing like it to compare with on Earth, because the entire crust has been churned under and regurgitated by metamorphic processes. The processes we can examine on Earth, by comparison, are nowhere near as energetic, and influenced heavily by the resulting chemistry from billions of years of subduction, a process which didn't occur on the moon.

Nearly everything that we could have seen before, during, or immediately after the impact is gone now, except for on the moon.

We can have a fairly good idea what the moon is like from understanding volcanic formations here on earth. Since the moon is geologically dead nothing has significantly changed in it's geological history, it's similar to newly-formed geological formations on earth, we have some idea of what we'd expect it's geology to consist of.

If they know what it's made of, in which porportions, how it was formed and what has happened since it formed (nada) then it's not really a big mystery what the geology or mineralogy is. I imagine we don't know everything precisely, but for our purposes, mineral/resource exploitation, we know it's not really all that exciting.

Basically, because the lack of water there means the type of hydrothermal ore deposits, of the type that create earth's mineral wealth, don't exist on the moon. We have extremely poor quality ores unexploited everywhere here on earth. Cheap energy might one day make them economically viable, but I can't imagine it ever being worth going to an entirely different world to scrape the bottom of the barrel.

[Andrew425]

Guys guys guys you don't seem to understand economies.

Any sort of metal is worthless if it's not on the earth and easy to get.

It will always be cheaper to build something on earth and send it into orbit then to build something on the moon.

Always.

So I don't think I could envision more then 400 people living on the moon. Unless they terraformed it but that is another ball game

[Starver]

Also, I'm really struggling to figure out why everyone is so excited about iron-nickle on the moon. Iron is already abundant here on earth, it's extremely cheap and iron mines and steelworks struggle to turn a profit. Or ice, for that matter. Ice is a dollar for a 10 lb bag, guys, it's not that big of a deal.

Personally I'm not as excited about the iron compounds as the (eventually processed) lighter metals that might be available, although there'll be uses for it.  But let's skip that and go to the water.

If water is available on the Moon, then we don't need to ship water (to be the entire supply, or replenish the losses in recycling) on either Moon bases themselves or, more importantly, in space.  Moon ice taken to Earth orbit would be a big saving on effort (especially if packaged up in a mass-driver compatible payload, so leaving the Moon won't even need Moon-made fuel for the rockets).

As has been pointed out, ice from asteroids/comets/Saturn's rings/wherever could be 'better' than the Moon (less energy, though longer in transit), but would take a while to set up.


The same extends to building satellites (or spacecraft intended to be built in orbit) on Earth and launching them.  If we can get the resources on the Moon (and, even better, do the refining and fabrication done there, so that we don't have to loft more mass than necessary), the various asteroid/Jupiter/Oort Cloud/Alpha Centauri missions can be got going without everything coming from Earth.  It's a cost for the initial infrastructure, but then it becomes a significant saving for the foreseeable future, and a good prototype (vacuum-pervaded hostile environment, if not gravity-less) for the asteroid-belt factory complex that may well drive the Moon-based system out of the mainstream business.

But these most basic ore-processing businesses are probably not meant to compete against Earthly ore-processing businesses in supplying Earthly supply chains.  There may be some things more cheaply made in space/on the Moon then transshipped Groundside, but I don't think it'll be bulk stuff, but specialist endeavours for which the natural airlessness and (off-Moon) gravitylessness are the key aspects...

Guys guys guys you don't seem to understand economies.

Any sort of metal is worthless if it's not on the earth and easy to get.

  I don't actually understand the nature of that argument, my apologies... however:

It will always be cheaper to build something on earth and send it into orbit then to build something on the moon.

Always.

YMMV, obviously.  I've just given my POV on the relative economics that might be a factor.

So I don't think I could envision more then 400 people living on the moon. Unless they terraformed it but that is another ball game

There will be no "terraforming" of the Moon, prior to a whole sea-change in known physics that allows such things as artifical gravity, gas-impermeable energy shields, etc...  This is Far Future Sci-Fi Tech stuff.  But there's no reason to believe that an outpost (or several) on the Moon for whatever purpose[1] could not extend to town size, with long-term tours of duty.  I don't know whether married couples would eventually be purposefully dispatched to settle the place, allowed to happen in situ or just that the 'family situation' would initially arise by mistake/accident, but the longer the settlement continues the more chance that there'd be native-born children, if that's what you're looking for.  But even a base that isn't a child-rearing one could be large enough through the sheer need to support the main (Research/Manufacturing/Exploration) crews with medical support, provision of supplies, operating the landing field operations, etc.  And, at some level, policing the sheer number of people who are there...

And there wouldn't be just one base.  Whether they're three-man research teams (who share the caretaker duties as well as their site-purposed ones) or such fully fledged infrastructures as described above that appear around the launching/landing areas that act as main bases, there'd be needs for some to be here, some to be there, some to be somewhere else...

'Huts' from which to maintain the farside radioastronomy sites, polar-region ice-crater monitoring/harvesting, mining claims needing at least temporary manning (regardless of automation) where the densities of various meteor-delivered/selenologicly-provided deposits are worth processing.

And I'd site the non-mass-driver locales significantly off to one side of the mass-driven trajectories, in case of under-run issues which mean suborbital trajectories of hulking big lumps of ex-Moon material plummeting back down to the surface, and I don't know if setting your major manned base even a few tens of kilometres off the equator would be considered safe enough in the event of some slightly deviated misfire of an equatorial mass-driver that sent the load spinning almost entirely around the circumference, should even happen.


[1] At least at first, for study only.  ISS-like.  Amundsen-Scott Antarctic Base-like.  That sort of thing.  But then... well... depends on what they find (or find they can do).  I predict refinement and extraction of various Moon resources, but how much, what proportions, from where exactly and for what purposes is so far unknown, because of the aforementioned "couple of geologists in the whole of Africa" issue.  But there are some good ideas.

[Tellemurius]

Well think of this, meteors do strike earth they are proportionally smaller than when they entered the atmosphere. Those big craters you see were caused by meteors that never shrank. Since there isn't much erosion on the moon those meteors theoretically are still a solid iron-nickel rock. Reasons why we are hyped up about is

a: we don't have to process it as a ore, while yes we do have a abundance of iron here the process is still time and energy consuming to extract pure iron from the ore.

b: its already a alloy, yes its a weak alloy but hell its still good.

Obvious to b though is that we would want steel and we need carbon for that.

[Derekristow]

There will be no "terraforming" of the Moon, prior to a whole sea-change in known physics that allows such things as artifical gravity, gas-impermeable energy shields, etc... 

Incedentally, we do have gas impermeable energy shields.  Well, technically they're called plasma windows, but it's the same general idea.  Not particularly useful without those fusion reactors that may or may not be feasible, but we have the technology available.

Mostly posting to watch, sorry for the slight off-topic tangent.

[GlyphGryph]

palsch, resposted that post of yours here:
http://forums.xkcd.com/viewtopic.php?f=9&t=73498&p=2872010#p2872010

[palsch]

Can I just say that the idea of having an economically profitable moonbase is absolutely laughable?

Let's take the He3 argument.

I'll go with a price of $10,000/kg. Turns out price is not all that important, but it's a starting point and easy to work with.

Let's give a rough price for establishing a self-sufficient and permanent mining base on the moon. I'll be very conservative, skip all research and development costs and go with the final price tag for Apollo. A NASA estimate had that at $170 billion in 2005 dollars. We'll start from that.

Because the base is self sufficient, we can say there are zero running costs once you have made that initial investment. We will focus on returning He3 only, given it's the most valuable material by weight we can send back. Now we only need to return 17,000,000 kg of He3 to break even.

Let's be generous and say that the average amount of He3 on the moon is towards the high end, at 50ppb in areas out of sunlight. That means you only need to process 340,000,000,000,000kg of regolith before your base has broken even. Yay? Of course, realistically you are looking at between 1.5 and 50 ppb across the entire surface of the moon, so we are talking a lot more than that.

And you really need to be able to sell it as well. It doesn't make much sense to base earth-based fusion reactors on He3 while we don't have a supply on it, and any lunar supply is likely to be very risky. At best you are going to want to send it back and stockpile it till you have enough to run an reactor for it's entire lifespan. Note that that isn't all that much; maybe 1500kg or so for a 1GW, 50 year reactor^*. Call it 1,700kg for the round numbers.

Now for our moon base to break even we would want to supply some 10,000 of those reactors with all the He3 they ever need.

Spoiler: * (click to show/hide)

A plant with a 1GW output would have ~5x10²⁰ fusion events per second. Each event burns 2 He3 nuclei for a total mass burned of ~2.5x10^-6kg. Running that constantly for one year adds up to 31.5kg. We will probably want to run the plant for 50 years or so, with some gaps for maintenance, so call it 1,500kg.

A moon base as an economically viable mining station doesn't make sense to me, at least for anyone stuck on earth. If such a base were to exist for other reasons it might be economically (and energetically; economics and energy conservation become one and the same at high enough levels) sensible to use lunar resources in certain areas where we would otherwise have to pay the higher costs of sending them up from earth. But that economic argument only comes once you have a moon base in existence and the economic benefit isn't to those who create it.

Such a base would need to be a blind investment. You pay for it for reasons other than future profit. Ideally you gain sufficient benefits here on earth, from the employment and new industrial/technological advances required to pull of such a program, that you don't have to justify it further economically. Make the entire profit argument irrelevant.

[GlyphGryph]

Essentially: It may not be pure profit, buts its a site better than digging holes and significantly better than broken windows.

[Eagleon]

Sorry guys, I have to.

We can have a fairly good idea what the moon is like from understanding volcanic formations here on earth. Since the moon is geologically dead nothing has significantly changed in it's geological history, it's similar to newly-formed geological formations on earth, we have some idea of what we'd expect it's geology to consist of.

The geochemistry of subduction and recrystalization here on Earth plays a very large part in what stays on the surface and what gets reintroduced to the mantle. Besides the fact that Earth's crustal chemistry has undergone enormous change since the impact, we have no idea how long and what kind of subduction occurred on the moon. Was it hydrologically influenced for a period, did heavier plates simply sank to the bottom? Or could heavier plates have been supported by lighter ones driving underneath? Convection in the mantle reintroduces heavy elements to be grabbed up by existing crystals, so it isn't quite so simple as dismissing basalt as 'just basalt' - you have microcrystals of many different minerals in any kind of basalt. Potentially, the crystals could grow to become recognizable as something different entirely, and that would make for happy mining.

Regardless, my point is that we don't know what happened after the moon started cooling. The sun would be a closer model of the moon's early stages than anything we have on the surface of the earth. Our surveying amounts to guesswork, assumptions, and a few sporadic samples, plus whatever we can glean from the surface with our instruments. No realistic mineral prospector here on earth would ever say that was enough to call a region barren.

palsch - Iridium from impact debris and probably many rare-earths once we run into shortages on Earth would be more valuable, with plenty of existing markets. Denser and easier to store, too. I'm not disagreeing with you, mind. It makes a lot of sense to me as a further stepping stone towards automated mining elsewhere, and of course as a production yard for any sort of endeavor in space. So for that 170 billion you're opening up expanding demand by sheer volume from an asteroid mining effort, the possibility of all kinds of research, and solar power where we wouldn't have to look at it, heh. It enables some things that are massively profitable.

[Starver]

Let me rephrase the economic argument for a Moonbase in simple terms: It isn't to provide increased profits for space-expansion industries, but to avoid future costs for space-expansion.

Now onto the more social aspects...  If it can be automated. it needn't even use people, but people are going to need to be there and I can't see humanity's space-future left to a three-man Apolloesque team sent down every year, for a couple of days at a time, so there will be long-term occupation either through a "tour of duty" system or potentially permanent residence by individuals.


Really, there are only two paths to the future that I can see where there is no Moonbase (or multiples, thereof):

• Humanity never gets to Lunar orbit or bryond, ever again.  Either stagnates in LEO, recedes back to the planet's surface or actually dies out, or
• It progresses so well with manned spaceflight that it quickly gets out to the asteroids and onwards, leaving the Moon as at best a handy gravitational slingshot mass and at worst is a pesky navigational hazard with an annoying gravitational well.

I find the former far too pessimistic, and the latter far too optimistic.  Whether whatever is left in-between is actually realistic, I shall leave up to destiny and fate to work out, but I've been fairly happy with my conclusions and expectations.


It is almost an aside from all of that that I very much hope that Humanity moves outwards in  whatever form.  This is my wish, not my conclusion.  But, as mentioned, should my wish be fulfilled I would find it surprising if it did not result in some (at least temporary) colonisation.  Possibly (if not probably) measured into generations, whether or not there's any serious attempt to make that include Luna-born generations.

And given there's some opinion dead-set against some or all of my own vision being practical, I thought I'd make a half-arsed attempt to make a concluding summary, in the above, to cover what I've been trying to say and acknowledging that YMMV (i.e. that however much I think some conclusions are wrong, or just red herrings, who knows how the future will swing).  I was hoping it would be as succinct as maybe a couple of paragraphs the same length as the first in this post, but it's already unmanageably verbose and self-referential.  I may, therefore, have to return to (carefully considered) rebuttals as of the ninja-storm period of a night or two ago, but I'm going to try to keep my volume down.  (I don't have a good record of that, though...)

[palsch]

Eagleon;

My main point is that earth-based companies, governments and other investors are very unlikely to see a profitable return from paying for a moon base. The commercial arguments I've seen fall down in areas like the one I demonstrated; the proposed profits don't take into account the scale of the investment. Either that or they depend on complete unknowns and speculative markets that, again, are huge risks given the commitment required.

Unless there is some demonstrable way to make a substantial profit in a relatively short term (say, 10 years) I don't think any commercial or economic argument is going to apply here. It's a bad argument to use for why we should do it, and using the argument distracts from the stronger reasons, letting people say it wouldn't be profitable therefore we shouldn't do it, ignoring any other factors by dismissing the market value of trace amounts or iridium in 2025.


My own view is to ignore earth either mostly or entirely. If we hit desperate requirements down here that lunar resources can satisfy, great. But for the most part it wouldn't be worth dropping any more crap into the earth's gravity well. Instead a lunar colony should focus inwards and forwards. Develop an internal economy and industry that finds it's own strengths rather than playing second fiddle to a terrestrial one, trying to plug holes and live on the fringes. Anything else would be focused on further expansion, in partnership with earth rather than as a supply depot.