Colonization of the solar system

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I'm not really interested in clones anyway.

@ bold: Which was rather the point of the movie. MY point was that the setting for the movie was a reasonably realistic representation of how lunar mining could be carried out. Nothing too "fantastical" about it, and mostly doable with technology either available now, or realistically in the near future.

Purely as an aside: Its not as if people being ethically expendable for commercial purposes actually stops them from being expended in commercial causes, so it seems even less likely that given viable cloning, said clones would be any less expendable than "real" humans, assuming they weren't extremely expensive, in which case they probably would be.

The clones in question are the plot-device. The "fi" part of the picture. They aren't relevant to the rest of the concept of mining the moon as depicted in said film, at least in this conversation.

What ores on the Moon are so valuable as to inspire the investment of millions or billions of dollars and all sorts of highly special efforts to obtain them by mining when they are so much more easily available on Earth?

Point, however if we want to go to deep space it would be cheaper to actually assemble and launch a long range spacecraft from the moon rather than Earth due to difference in gravity.

The initial investment in setting up lunar mines would probably far outweigh the cost of mining on Earth, construction in orbit and launch from zero gravity.

That is predicated on the kind of propulsion systems we now have. The technology for a decent propulsion system is yet to be developed (if it ever will be). We are still using technology that the Chinese applied to their rockets 2000 years ago. The Chinese invented the Solid Fuel rocket.

ruveyn

The only possibility superior would be a tethered space station with a space elevator. We haven't the materials for that but possibilities may arise. That still would make zero gravity construction and launch a better deal than an industrial complex on the Moon.

So, a StarLadder is more feasible than using materials from the moon to build spacecraft from, I see. Whatever floats your boats.

Since there is no lack of suitable material on Earth and, in emergencies, the proximity of Earth is much more suitable for quick rescues and since all the fabrication capabilities already exist on Earth, a space elevator is a far better solution and far more economical. Unfortunately the structural material for the elevator does not exist and there is no guarantee it ever will.

The suitability of materials might as well be the same as on Earth. Cost of fuel to lift them from Earth's surface into orbit is a lot more than lifting them from the lunar surface into orbit. Heck, on the moon a starladder might actually be possible to build as compared to here on Earth, less gravity and less politics to say the least, although the extremely slow rotation would require a lot longer distance to emulate Earth gravity. Mars rotates at, basically, Earth's rate of rotation, so perhaps construction of a starladder ( or multiple of approximately the same mass on opposite sides of the planet to allow for longer term stability) on Mars might actually work. Building one on Earth would be a feat in both physics and politics though.

Jumping back for a moment to nuclear spacedrives:

There are three propulsion systems that involve nuclear reactions. The one we have actually developed thus far, the ion drive, uses electricity to charge the reaction mass (generally a rare-earth element, as those tend not to clog the emitters so rapidly), then give the metal emission grid an opposite charge; the basic concept of rocketry is throwing mass in a specific direction as hard as possible, so there you go. For the most promising developments in this field, I recommend looking up the specifics of the VASIMR coupled-charge plasma drive, which could be used to drive a manned spacecraft with a constant acceleration as high as .005g. Doesn't sound like much, I know, but that much constant thrust (reversing to deceleration at the halfway point, of course) would get you to Mars in a couple of months, or to Pluto in less than a year...

Two others were under development at one time, but were outlawed by certain interpretations of the UN's Outer Space Treaty (the relevant portions were intended to outlaw orbital rocket platforms, but some folks just have to push the envelope): NERVA, and the Orion Drive.

NERVA basically uses its propellant as coolant for a nuclear reactor; the superheated coolant is then vented out the rocket motors, rather than being cooled and re-used. Popular images of this led to the misconception that the reactor's actual core was being sprayed out all over the solar system; this, combined with a total lack of understanding of just how huge the solar system is, resulted in NERVA research being shut down. (Would you believe there are actually people concerned about our measly few dozen probes "polluting space"?)

Orion's concept is even simpler. Take an arbitrarily large craft - you could craft it from an entire asteroid, if you like. Mass isn't that big a concern, as will be seen below. Attach to that craft a massive steel plate, with some really good shock absorbers. Place a nuclear bomb on the other side of the plate. Set it off. I guarantee you, that ship is going to move. However, shipping nuclear bombs into space does get a bit problematic - the hard part is ensuring they're going to be used for a space drive, not dropped back onto Earth. Another idea involves using laser inertial confinement and deuterium pellets, but full development of such a system would have to take place in a microgravity environment, which kind of leaves you in a Catch-22 situation.

None of these drives are intended for leaving Earth's surface, of course - the only one that's likely to develop enough thrust to escape a 1-g field, the Orion system, has - er - rather dramatic environmental effects...

helium-3 seems to be what i'm hearing most interest about, in terms of moon-mining.

I dunno, how about all the ones that we are busy using up on Earth? The less there are of those here, the more valuable they get everywhere else.

agreed.

Delightful picture, except that it isn't FOR that. It's for SPACE travel, not lift-off. Might as well have a picture of an F111 failing to take off from a multi-storey car-park, or an Aircraft carrier trying to negotiate the Shropshire Union Canal.