dietz@cs.rochester.edu (Paul Dietz) (01/20/89)
In article <5740@cbmvax.UUCP> jesup@cbmvax.UUCP (Randell Jesup) writes: >>* Lunar materials to support other space industries (eg LOX) are not >>worthwhile until such industries generate the $100+ billion/yr plus >>demand needed to pay for such a base, and such materials can be made >>and transported cheaper than from Earth or asteroids. > > 100 billion PER YEAR? Seems rather high to me. Asteroids are >very far away (energy-wise), and are unknown quantities for the most part >(compared to the moon). If you learn one thing about asteroids, it should be that some are much *closer* than the moon, energy-wise. 1982 DB (does it have a number & name now?) can be reached from LEO with a 4.4 km/s delta-v; it takes 6 km/s to get to the lunar surface. To return to LEO from 1982 DB requires as little as 0.1 km/s delta-v, using aerobraking; from the lunar surface, about 3 km/s. So, the energy cost of returning material to LEO from asteroids is *spectacularly* lower than from the moon. Asteroids also have the important volatile elements, especially hydrogen, that are essentially absent on the moon. Asteroids are not complete unknowns -- we have samples: meteorites -- but surely ignorance is a reason to explore them, not ignore them. If 1982 DB were 1962 DB, we'd have pieces of it in the Smithsonian today. The case for asteroids can only get better as we find more of them. As of 1/88, 104 earth-approaching asteroids were known, less than .1% (estimated) of the population >= 100 meters in diameter. Paul F. Dietz dietz@cs.rochester.edu