space@mit-mc (03/02/85)
From: Dale.Amon@CMU-RI-FAS There is at least one mountain peak at the North Lunar pole that is always in sunlight. It is also true that craters there are always in shadow, thus the idea that water might exist in the ultralow temperatures. Some have suggested that ion sputtering may have destroyed any water that existed there. Anyway, I digress. A solar collector could be run there. You could also use the eternal temperature difference for a heat-engine, particularly if you use a mirror to increase the temperature of the hot pole, and thus increase the amount of work that can be extracted from the system. I believe there may be some discussion of this idea in the literature. In fact I think there was a paper on it presented at the Lunar Base Symposium in DC last October. As to the lunar soil, I believe that it has a high thermal conductivity, and thus your heat sink would rapidly warm up the surrounding several kilometers by a few tenths of a degree. (If anyone out there has the real conductivity figures, please jump in). I'd really suggest a small fission reactor. You don't even need shielding. Just stuff it in a convenient crater. Same thing with the waste products. They certainly aren't going anywhere. Once things the economics are right, you'll probably beam energy from an SPS as an additional source. Someone also was asking about the titanium in lunar regolith. The lunar highlands consists of a quite reasonable ore grade for titanium. I believe it's on the same order as the rutile sands in Australia where we currently get most of our titanium. I'd also suggest that anyone interested in these topics read through the SSI/AAS Space Industrialization proceedings. You'll learn an enormous amount and avoid reinventing the wheel, the hub and the chariot. I'm glad someone finally jumped in with facts on the Drexler light sail. I was about ready to give Eric a call and have him dictate an answer. By the way, he has a book coming out next fall on molecular engineering. Watch for it. A space burial via solar sail is certainly not going to attain .999c. However, using a very high power laser, like the SDI ones and a VERY good mirror, it might be possible to reach terminal velocities that are substantial fractions of c. Those same lasers would be quite good for building Dr. Kantrowitz's laser launchers. That concept is a simple ceramic combustion chamber with pulsed lasers supplying energy from the ground. The initial reaction mass is the air that rushes into the chamber between pulses. Some additional mass may be needed for orbit injection. The beauty of the process is that it puts things in orbit for a few dollars/pound. I think a good milestone to use when looking at orbit costs is the potential energy of an object at orbital altitude and it's kinetic energy at orbital speed. I'm too lazy at the moment to recalculate the numbers, but I believe in terms of KWHrs, it should only cost pennies/pound. As to music, I think we've now got enough members for the first lunar pick up band: Guitar, bass, cello, piano... (is there an electronic drummer out there?) How about calling ourselves (groan) "The Space Invaders"?