Quote: Original post by BeanDog
Unfortunately, the moon is dead, and as far as we can tell it was never alive. So no petroleum. But it's possible there could be some other element there that's rare near earth's surface but abundant on the moon's surface, like Uranium or something. I wouldn't count on it.

I think it's not about the minerals, but about being able to build and launch things from there, even to our own orbit. It'd be orders of magnitude easier and cheaper. It'll be also outstandingly useful to re-fuel space-ships.

It is the first necesary step in order to start the conquest of our solar-system.

EDIT: spelling

[Edited by - owl on March 2, 2010 6:26:28 PM]

They say if humans are going to adapt to flight it will be on the moon.... I'm so there. I'll go mine some dirt and drink water........... maybe I'll find something radioactive to play with.... o-o

For commercial ventures there's always the methane moon around Jupiter Saturn.... psst for invite!

Quote: Original post by owl
I think it's not about the minerals, but about being able to build and launch things from there, even to our own orbit. It'd be orders of magnitude easier and cheaper. It'll be also outstandingly useful to re-fuel space-ships.

Unless the moon has useful minerals, wouldn't it be easier or cheaper to either build it on Earth or have an orbital space station? If your lunar base is getting its resources from Earth, you've still got to pay the fuel cost to ship the stuff to the moon in the first place; you're better off just building it here rather than involving a second gravity well. And if you need zero/low gravity for construction or refueling, you might as well use a space station and save on launch and re-entry costs.

Quote: It is the first necesary step in order to start the conquest of our solar-system.

I could see this as a reason, but only because the Moon is the closest rock to colonise first. But I doubt there's going to be a strong push to colonise the solar system any time soon. It's just way too expensive to set up and maintain.

Quote: Original post by Trapper Zoid

Quote: Original post by owl
I think it's not about the minerals, but about being able to build and launch things from there, even to our own orbit. It'd be orders of magnitude easier and cheaper. It'll be also outstandingly useful to re-fuel space-ships.

Unless the moon has useful minerals, wouldn't it be easier or cheaper to either build it on Earth or have an orbital space station? If your lunar base is getting its resources from Earth, you've still got to pay the fuel cost to ship the stuff to the moon in the first place; you're better off just building it here rather than involving a second gravity well.

That's actually the point of building stuff on the moon - it has a much weaker gravity well, and once you're out around the region of lunar orbit it doesn't take much more push to get you out into the solar system.

For comparison, the Earth has an escape velocity that is somewhere between 9 and 10 kilometers per second. The moon, by contrast, has an escape velocity that is somewhere between 1 and 2 kilometers per second. It takes about 3.2km/s (IIRC) of delta-V to get from LEO to a translunar trajectory, and a little more to capture into a lunar orbit. Even more to get down to the moon. But to come up to lunar orbit, you need less than 2km/s of delta-V. There are some other reasons favoring lunar industry for spacecraft manufacturing: the moon has no atmosphere, so it's easy to launch from; it has plenty of minerals and metals (lunar regolith contains a large amount of aluminum oxide) that you can strip-mine without worrying about damaging the environment; and you can process oxygen from the lunar surface and use it to refuel your ships.

The first point coupled with the moon's lower gravity make it much easier to build single-stage-to-orbit, reusable cargo spaceships for use on the moon. SSTO is something that is much harder to achieve on Earth not only due to its atmosphere but also due to the fact that you need to go 7km/s just to go into a low orbit, never mind going to escape velocity (as you would need to in order to get elsewhere in the solar system). Nobody as far as I know has managed a true SSTO launching from Earth. There's been a couple of rockets that could have done it, but with negligible payload... There's also the Skylon proposal, but they haven't received much in the way of funding and I don't know that they've even gotten to cutting metal yet. On the other hand, the Apollo LEM ascent stage was a lunar SSTO that was built with 1960s technology and carried two humans plus equipment.

The second point means that resources are plentiful for manufacturing industries up there. The third point means that some of the burden of fuel costs can be lifted from Earth. Assuming the use of hydrogen as a fuel, oxygen makes up a huge percentage of the fueled or "wet" mass of a spacecraft; oxygen has an atomic mass of 16, hydrogen has an atomic mass of 1. If the ship only needs to bring its hydrogen fuel along with it from earth and can replenish its oxidizer stores, that means that it needs to carry only 1/9 as much total propellant to the moon with it before refueling. That makes a pretty big difference.

Add to that the fact that given good heat-shielding technology and the fact that it's much easier propellant-wise to bring something from lunar orbit back to land on Earth (thanks to aerobraking and reentry not actually requiring much propellant, just a good heatshield and recovery system) and you have some of the reasoning behind the slogan "Garden Earth, Industrial Moon." Until that industrial base gets built up there, however, it will be cheaper to manufacture spacecraft on Earth. And thus exists the catch-22.

[Edited by - Oberon_Command on March 3, 2010 12:59:11 AM]

Quote: Original post by BeanDog
But it's possible there could be some other element there that's rare near earth's surface but abundant on the moon's surface, like Uranium or something. I wouldn't count on it.

Current thought is the moon might well be covered with plenty of Helium-3 which is seen as an important fuel for fussion research/reactor development.

The only problem is even given the cost of Helium-3 on earth it still would cost too much to ship it back from the moon [sad]

Quote: Original post by Oberon_Command
it has plenty of minerals and metals (lunar regolith contains a large amount of aluminum oxide) that you can strip-mine without worrying about damaging the environment; and you can process oxygen from the lunar surface and use it to refuel your ships.

Ah, I'd be careful with this, as it is not necessarily true as a blanket statement. Certainly, at first sight, it looks that way, but it is a very dangerous view.
You may object that what I'm saying here is ridiculous, and maybe it is, but then again, maybe it is not. History has many examples of man saying "oh it doesn't matter" and finding out 50 years later that entire ecosystems are destroyed forever because of some cascade effects that nobody thought about.

If you keep building starships and launching them, you will inevitably reduce the moon's mass. Granted, with its 1022 tons, the moon's mass is big enough so we probably won't consume it all until next tuesday.
On the other hand, if people go about the moon in a general "we don't need to care at all because moon is dead already" fashion, it might very well be that after a time span of maybe 50 or 100 years, we discover that the massive overexploitation of the moon begins to cause noticeable effects on earth, which we then will not be able to undo.
I'm not an expert on tidal ways, so I couldn't say whether a difference of 0.00001% or 25% in moon's mass makes a "significant" difference, but surely this is something that could become noticeable at some point, if people treat moon as blanket exploit-for-free for decades. So what happens if there are no more tides, or just slightly different tides? I don't know. Nothing at all might happen, some sea currents might change, or 3/4 of all fish in the oceans might die within one week due to some reason that we don't understand. Also, the owners of tidal power plants might get pissed :-)
I'm not sure what exactly are the implications on moon's orbit or earth's rotational axis, either, if one keeps generously removing mass. Well, I'm pretty sure that the moon won't fall into the mediterranean sea, but you know what I mean... the effects may be non-obvious now.

Quote: Original post by samoth

Quote: Original post by Oberon_Command
it has plenty of minerals and metals (lunar regolith contains a large amount of aluminum oxide) that you can strip-mine without worrying about damaging the environment; and you can process oxygen from the lunar surface and use it to refuel your ships.

Ah, I'd be careful with this, as it is not necessarily true as a blanket statement. Certainly, at first sight, it looks that way, but it is a very dangerous view.
You may object that what I'm saying here is ridiculous, and maybe it is, but then again, maybe it is not. History has many examples of man saying "oh it doesn't matter" and finding out 50 years later that entire ecosystems are destroyed forever because of some cascade effects that nobody thought about.

If you keep building starships and launching them, you will inevitably reduce the moon's mass. Granted, with its 1022 tons, the moon's mass is big enough so we probably won't consume it all until next tuesday.
On the other hand, if people go about the moon in a general "we don't need to care at all because moon is dead already" fashion, it might very well be that after a time span of maybe 50 or 100 years, we discover that the massive overexploitation of the moon begins to cause noticeable effects on earth, which we then will not be able to undo.
I'm not an expert on tidal ways, so I couldn't say whether a difference of 0.00001% or 25% in moon's mass makes a "significant" difference, but surely this is something that could become noticeable at some point, if people treat moon as blanket exploit-for-free for decades. So what happens if there are no more tides, or just slightly different tides? I don't know. Nothing at all might happen, some sea currents might change, or 3/4 of all fish in the oceans might die within one week due to some reason that we don't understand. Also, the owners of tidal power plants might get pissed :-)
I'm not sure what exactly are the implications on moon's orbit or earth's rotational axis, either, if one keeps generously removing mass. Well, I'm pretty sure that the moon won't fall into the mediterranean sea, but you know what I mean... the effects may be non-obvious now.

The moon's mass is : 7.475 × 10^22 kgor:74,750,000,000,000,000,000 tonsThe biggest copper mine on earth extracts:                   450,000 tons x dayIf such mine was on the moon it would take:166,111,111,111,111,111 daysor:    455,098,934,550,989 years    To deplete the entire moon and:            455,098 yearsTo consume 0.0001% of it's mass.

I believe in the course of 500,000 years of space exploration lots of things should change in relation to Earth's ecology. So I wouldn't worry very much about tidal changes.


Sources:
Mass of the moon
Bingham Canyon Mine – Largest Man Made Excavation

Quote: Original post by phantom
The only problem is even given the cost of Helium-3 on earth it still would cost too much to ship it back from the moon [sad]

That's assuming you launched everything on earth and you used rockets. I would think that industrial-scale He-3 production would rely on a big industrial base on the moon and massive linear accelerators/catapults for launching the cargo back, since such a scheme would only use electricity. And again, if you give it a heatshield and launch it at the right time and in the right direction, you don't even need to put a rocket on it.

You could probably also use that same industrial base (if it existed, which it currently doesn't) to build space-based solar power satellites for cheaper than if you had to build them on Earth.

As for fears of us 'depleting' the moon, or changing its mass and thus orbit, you also have to take into account that the moon is already a variable mass body! The same as earth.

We are impacted all the time with extra mass from space, and in the case of the moon it can also lose mass if hit at the correct angle. (Because of the low escape velocity.)

What we really need is Harvesting and General Fabrication probes put onto the moon. Using solar based energy harvesting (Traditional solar panels for energy, and reflectors for heat) you can take a small factory (Think Apollo payload levels) that could extend itself. Given 10 years of operation you could see it spreading itself and establishing a basic foundation for rapid expansion.

For recovery you can even just use the Mass Slug Drop and recovery methods. Encase a few hundred tonnes of Aluminum in a very simple heat shield, and simply let it impact in the middle of some desert. You come in a few days later and start cutting up the slug out of your new 'mine' in the middle of no where with minimal breaking.

Quote: Original post by samoth

So what happens if there are no more tides, or just slightly different tides?

No need to worry about it, global warming will compensate. :p
But realistically, mankind never cared about spitting in its own bowl, as long as the bowl was out of sight.

And if recent Haiti and Chile experiences have anything to say - man should be humbled by what nature can produce casually - let alone if it gets seriously angry.