[X] My Assistant

[Greg Hullender]

Well, to be fair, it was a lot easier to find new and surprising things back then. Pioneer 10 was pretty crude, but it told us amazing things about Jupiter and it's moons, since up until then we knew almost nothing. Heck, Mariner 2 flew past Venus with just two instruments (if I remember correctly) and yet it told us that Venus didn't have an ocean -- that it was burning hot. Amazing results from pretty primitive tools.

Today we can still get amazing results, but it needs much more preparation, much more sophisticated tools, and much more sophisticated analysis of the data that comes back. Even the cool results (not counting pictures) aren't as accessible to ordinary people.

On the bright side, with the Internet, it's much easier for "educated laypeople" to be involved today -- witness UMSF itself. Also, some of the new technology does make it easier to make the more-sophisticated probes and to do the more-sophisticated analysis.

The real thing that's missing is the lack of any serious economic or military incentive to go into space. Comm satellites and weather satellites are great, but that only goes so far. (Ditto spy satellites -- I think.) :-) Space manufacturing seems to be a complete bust, and Space Tourism is still, ah, a bit too pricy. Without anything like that, progress happens at a snail's pace, and what does happen is effectively thanks to pure charity.

At this point, it's hard to see that changing in the next 50 years, although who knows? I still remember how hard we laughed at the idea that anyone would consider e-mail valuable. :-)

--Greg

[nprev]

To paraphrase Fredric Brown in his obscure but brilliant novel The Lights In The Sky Are Stars: why stop climbing a flight of stairs once you find a few handfuls of treasure? Very hard to translate this principle into the (badly needed) near-term economic returns that small businesses require--esp. if the 'handfuls' are elusive--but the ultimate goal is potentially beyond all our wildest dreams. We are talking about the rest of everything there is beyond the Earth, after all....

[edstrick]

"...Fredric Brown in his obscure but brilliant novel The Lights In The Sky Are Stars:..."

Another -- then unimaginable -- story of an abandoned space program and the obsessive dreamers who forced our way back to space is Dean McLaughlain's "The Man Who Wanted Stars", from 1965.

[ngunn]

For me the ultimate parable about a civilisation turning it's back on the universe is Arthur C. Clarke's "The City and the Stars". There's still a movie opportunity there, I feel.

http://www.adherents.com/lit/bk_Clarke_CityStars.html

[Greg Hullender]

The theme of abandoning the stars is more common than you might think. A character in Asimov's "The End of Eternity" mentions humanity colonizing and abandoning Mars and Venus repeatedly over a (roughly) million-year period.

I like to think there's something valuable on the Moon that would make the huge cost of building the infrastructure worthwhile. For example, suppose you could fabricate Titanium there on a large scale. With a Lunar space elevator (MUCH easier than one on Earth) you could lift the stuff to the L1 point, then with very little thrust, send it on one of those long "IPS" trajectories and finally use aerobraking to drop it on Earth.

Question is, could this possibly ever be cheap enough to compete with metals refined on Earth? At least there are no enviromental concerns, but the low gravity hurts (we depend on it to separate molten metals), the lack of water hurts two ways (harder to refine without it, and less likely to have metal deposits in the first place without it), etc. It doubtless has unique advantages too (e.g. running a nuclear plant with minimal concerns, since there's no water table and no atmosphere to spread any contamination), but learning them would take time.

Anyway, a comprehensive plan -- to my way of thinking -- would include developing that infrastructure -- probably at government expense -- with an eye towards enabling private industry to exploit the natural resources of the Moon. Once that starts happening, access to the rest of space seems to follow naturally. (At least, it's not so great a leap.) But it really seems like it needs that one big step before it can get going, and it's hard to see how we get there from here.

Anyway, setting up proper lunar bases -- much as we have Antarctic bases -- seems like an indispensible first step, and something I really wish we'd done long ago.

--Greg

[helvick]

"Mining" resources in any gravity well in order to get them to another one always struck me as totally nuts and almost all of the materials that might be available there are already plentiful here and will always be cheaper to mine here than there if you want to use them here. (For any of the typical values of here and there like "The Earth" and "The Moon" or "The Asteroid Belt"). Delta-V is an expense that you are better off avoiding at all costs.

Let's just work through the energies involved in moving a ton of mined something from the surface of the Moon to the Surface of the Earth.

Moon to Earth Escape Velocity is around 2.27km/sec. That means we have to imaprt about ~ 2.5 GJ / ton to accelerate our goods up from the surface of the moon - assuming we have some hyper efficient rail gun type launch mechanism etc etc. That's not so bad as its only about ~ 10% of the energy cost of refining a ton of steel, 2-3% that of aluminium and <1% of a ton of Titanium. So far so good.

Now we're falling in to Earth on a purely ballistic trajectory and building up some serious kinetic energy on the way in that we'll have to burn off somehow or other. Give or take some loose change that will be about the same as the kinetic energy we would need to add to an object to bring it to earth escape velocity (11.1km/sec). For a ton of inbound material that's around 60GJoules. If you are going to use aerobraking to land your payload on earth then you might want to consider the environmental effects of dissipating that ~60GJ of energy per ton of landed payload. Just to get the ball rolling that's about 10 times the amount of energy required to atomize a ton of iron by the way so I really can't see that scaling that approach up to industrially useful volumes for common materials. As it happens you could actually land quite a lot of iron this way since much of the heat is bled off making plasma out of the air as well as the iron but that all combines to make a serious mess in the atmosphere on the way in and there would almost certainly be a big hole in the ground at the end.

Or at least that's how it seems to me. I may have completely mis understood something in this though so if I have made a glaring mistake then feel free to point it out. If not then the above numbers mean that it is insane to try and mine almost anything "up there". Apart from the antimatter mines off the solar poles that is.

[Juramike]

I agree with Helvick about the difficulty of moving bulk mined metals down to Earth, but I'd like to offer antoher downside: liability.

If an ore truck tips over on a highway, it's makes a mess on the road.

But if a retro/parachute fails on re-entry, the inbound slag will take out a subdivision. The lawyers would have a field day.

No company dealing in commodities would ever be able to afford that level of insurance to cover a "re-entry issue".

[Greg Hullender]

I think you've completely misunderstood something. :-) First off, note that the Apollo Command Module weighed a ton and a half, yet it had no reentry troubles. Obviously there is some way around the problem you describe.

I found this illuminating: http://en.wikipedia.org/wiki/Heat_shield#E..._considerations

Among other gems, the Galileo probe disipated 380G joules, losing just 1/4 of its weight in the process.

As for the liability issue, I don't think it survives serious examination. First, you wouldn't bother with a parachute; you'd just drop the things in the desert. Second, the odds of hitting anything else are awfully low. Finally, it's just a ton of metal at terminal velocity; no worse than the occasional plane crash -- and without the jet fuel.

--Greg