Aucbvax.4340 fa.space utzoo!decvax!ucbvax!space Fri Oct 9 04:42:17 1981 SPACE Digest V2 #9 >From OTA@SU-AI Fri Oct 9 04:36:40 1981 SPACE Digest Volume 2 : Issue 9 Today's Topics: Energy & SPS Finite energy ---------------------------------------------------------------------- Date: 8 Oct 1981 1132-PDT From: DIETZ at USC-ECL Subject: Energy & SPS To: space at MIT-MC Another problem with SPS is the incredibly long lead time. This is the same problem with nuclear plants also (although some of the dealy may be caused by the anti-techs and government regulations). Freeman Dyson has pointed out that the best engineering projects are those with a lead time of less than 5 years, because after you pass this point the problems begin changing faster than the solutions. Also, it becomes very difficult to correct mistakes (like using scaled up SUBMARINE reactors (!) for nuclear plants). This is the crux of the matter. Who is going to invest in SPS when it is (admit it) so risky? There's a good chance that some other inexpensive energy source (dirt cheap solar cells, fusion, bacteria that make gasoline) will be developed before it's even off the ground. J.P. suggests using solar power in military missions. Wouldn't a solar powered military satellite be very vulnerable to attack? Finally, I had the impression that it's hard to use lot of power in space because of problems in disappating waste heat (only radiation, no convection). Is this correct? It wouldn't be a problem with a SPS (the thing is large enough to cool easily) but might be a problem with, say, refining metals in large quantities. Here's a question for the physically minded: how long does a 1 kg. spherical piece of molten aluminum take to cool to a reasonable temperature? 1000 kg.? ------- ------------------------------ Date: 8 Oct 1981 23:02:53-PDT From: E.jeffc at Berkeley To: v:space@mit-mc Subject: Finite energy Actually, what is all this talk about limited energy anyway? Ok, we'll run out of oil soon, and nuclear power has been made uneconomical by the lunatics in our society, but what about fusion energy??????? I say we should develope that as fast as possible. It is superior to SPS anyway for very good reasons. First, it will not be as capital intensive. Second, it permits much higher energy densities to be realized. The problem with solar power in any form is that it is deluted. Sure, you can collect as much energy as you want with a large enough collector, but the density of that energy is rather low compared to that provided by a fusion reaction. In order to run our every increasingly technological society, we will not only need more energy, but in higher densities as well. This would be true even in a space environment. A spaceship of the future will obviously have a fusion drive, if possible, and a large space station, or city if you want, will need simply too much energy to be feasibly supplied by a solar collector. I believe that solar power is good for running a eco-system, and transitor radios, and very little else. ------------------------------ End of SPACE Digest ******************* ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.