Aucbvax.4556 fa.space utzoo!decvax!ucbvax!space Tue Oct 20 04:20:17 1981 SPACE Digest V2 #16 >From OTA@S1-A Tue Oct 20 03:50:32 1981 SPACE Digest Volume 2 : Issue 16 Today's Topics: Administrivia SPS vs. Fusion - A response to REM / counterresponse Selling SPS as a weapon SPS as weapon Radiation pressure and and how it applies to SPS Addendum to my previous message about radiation pressure Drawbacks of SPS, hazards of fission use Begg talk at Hahvahd ---------------------------------------------------------------------- Date: 15 Oct 1981 2255-PDT From: Ted Anderson Subject: Administrivia To: space at MIT-MC The distribution of the SPACE Digest has changed venue. It is now being run from site "S1-A". The only change you should notice is that this system does not allow anonymous FTP so send mail to SPACE-REQUEST@MC to request back issues or whatever. -Ted Anderson P.S. Naturally, if I elect to take a vacation for a few days, you can count on the space digest automatic distribution system screwing up as soon as I leave. So tonight we have four days submissions for the price of one. -ota ------------------------------ Date: 16 October 1981 10:31-EDT From: Robert Elton Maas Subject: SPS vs. Fusion - A response to REM / counterresponse To: DIETZ at USC-ECL cc: SPACE at MIT-MC One quibble. As far as we know there's no single "bullet" that can kill fusion. But there just might be, we don't know. Maybe like the second law of thermodynamics (negentropy can't be increased), there's another basic law of physics that says you can't confine fusable fuel long enough to make it fuse continuously unless you use a gravitational well to do it. If so, the only way to use fusion energy is to explode bombs (unless you have a black hole or a star handy). -- This is just idle speculation. Don't take it too seriously. Otherwise: you have some good points. My answer, let's hurry and get funding to start space industry. The sooner we get started, the sooner we'll know what is practical and what isn't. However, I quibble a little with your problems. You don't need to have the factory run in a vacuum. If necessary, you can run most of it inside a chamber containing a nitrogen atmosphere. Gravity can be simulated by rotation. I also have confidence that moon materials can be electrolyzed into individual elements if necessary, at which point you have the same elements to be found on Earth and thus no new problems not already encountered here. Does anybody know if anybody has actually tried processing some of those moonrocks brought back by Apollo? Or are they so valuable nobody wants to damage them? ------------------------------ Date: 16 Oct 1981 1530-CDT From: Jon Webb Subject: Selling SPS as a weapon To: space at MIT-MC cc: cs.webb at UTEXAS-20 (I sent a couple related messages on this subject to ARMS-D) Who's got the bucks? Well, it sure ain't the Department of Energy or NASA, who might build SPS as a energy or space system. And the energy industry here has way too many sure things they can do will all their money to build a risky, expensive thing like SPS. So we need a new source of funding for SPS. What does the US need? Energy? You've got to be crazy. When was the last time we had a gasoline crisis? It's been years. And there is very little support for the space effort nowadays. What the US needs is POWER. Not energy, but political power. SPS provides a unique source of that power. With a concentrated SPS beam (say, 4-6 times regular sunlight) we can destroy crops. We can evaporate rain clouds. In short, we can really screw up a third-world country we don't like. For example, suppose we wanted to punish Khadaffy for his recent inflammatory statements. Zappo! And a lot of heat can mess up an industrialized country, too, but consider what a microwave beam could do. Microwaves are suspected of causing bad things like cancer, cataracts, and heart attacks at extremely low densities. There would be all kinds of nasty uses for a powerful microwave beam that could be projected from orbit. Finally, SPS (as a weapon) provides a literally visibly symbol of US power. You could see it at night. It would be up there, over our heads. Think of a huge hand, holding a magnifying glass 22,400 miles above our heads. On the wrist is tattooed "U.S.A." And think of the command-and-control you can do from there. I can think of no better place for a general (or even, maybe, for our president) than in orbit. Plus, in peacetime, the thing can be used as an energy source. Jon ------------------------------ Date: 16 October 1981 22:08-EDT From: Gene Salamin Subject: SPS as weapon To: SPACE at MIT-MC Well, if an SPS is constructed with the intent of maybe using it as a weapon, then it will be designed so its phased array transmitter does not require a pilot beam when in weapon mode. ------------------------------ From: FONER@MIT-AI Date: 10/16/81 23:16:07 Subject: Radiation pressure and and how it applies to SPS FONER@MIT-AI 10/16/81 23:16:07 Re: Radiation pressure and and how it applies to SPS To: Space-Enthusiasts at MIT-MC This is a subject that was covered in some depth about a year ago on this very list. While I do not remember exact figures, and do not want to go through the required calculations to find out again, they exist in archives somewhere. The basic ideas are as follows: you get a particular amount of radiation pressure from the sun. This is not much... maybe a thrust of a few (500?) newtons (this is the same force as applied to about a 50 kilogram weight in 1 G for nonphysics fans). Not much. (Note I assume a "typical" collector area of some tens of kilometers squared.) You also get thrust from the beam pressure as well. An initial calculation showed this to be on the order of maybe 5000 newtons, but that was later changed to about 20 newtons (40?). Something like that. Very little thrust, and very easy to compensate for. Could someone with more time and a higher-speed connection to MC see if he or she can find the relevant letters in the archives? I'm pretty sure they were just about a year ago. Have fun. ------------------------------ From: FONER@MIT-AI Date: 10/16/81 23:18:04 Subject: Addendum to my previous message about radiation pressure FONER@MIT-AI 10/16/81 23:18:04 Re: Addendum to my previous message about radiation pressure To: Space-Enthusiasts at MIT-MC It occurs to me that the subject may also have been germane to the Energy@MIT-MC list. It's quite possible that I'm confused, and that the old messages on SPS radiation pressure were sent to that list and not this one. Anybody wanna search that archive, too? Ciao. ------------------------------ Date: 19 October 1981 01:48-EDT From: Jerry E. Pournelle Subject: Drawbacks of SPS, hazards of fission use To: HASTINGS at CMU-20C cc: SPACE at MIT-MC Re vulnerabilities: are supertankers safe from enemy action? Even anonymous enemy action? Surely it is easier to knowck ouot an oil field or the Alaska pipeline than to knock out an SPS. But yes, they are somewhat vulnerable. Re fission and operators, I'm willing to give up fission if we can have space power systems; what will happen, though, is that SPS is now opposed in the name of fusion; but when fusion will actually work and put kw into the system, they'll have lots of reasons why it shouldn't be used either. The anti-Amerika Krowd isn't so much opposed to any particular technology unless it would WORK... ------------------------------ Date: 19 Oct 1981 2220-EDT From: J. Noel Chiappa Subject: Begg talk at Hahvahd To: space at MIT-MC cc: JNC at MIT-XX, mph at MIT-XX, ludwig at MIT-XX, wayne at MIT-XX I just got back from a talk that he gave at Hahvahd to the Astro society there. My general impression of the man is that he is not a 'politician', honest to a fault, seriously interested and committed to space, and enough of a realist to deal with running a major government agency. In short, I am impressed. His talk was not too interesting, but the questions/answers afterward were a gold mine. The only interesting thing in his talk was that he gave prominent mention to the LEO station as a major goal after SpaceTel, Galileo and VOIR. He was also interested in remote operated moon mining stuff in the medium (10 year) range. Sounds familiar! As to the questions: he made a strong commitment to keeping the Deep Space network running, and to continuing with the Voyager on to Uranus and Neptune. He feels that there is growing commitment to space among the general population and in Washington as its role as a technological ground breaker is appreciated more (there was an undertone of competitive nationalism against Japan/Europe in this). He feels that the big policy statement from the OSTP will be a long time coming and not be very forceful when it does. His most important operational commitments is getting the shuttle operational and economic (he had two less important ones, the second of which was laying long-range plans, but the other has faded from memory - it might have been keeping appropriations from further cuts). He is encouraging to commercial commitments, and hopes to see them grow. He is very interested in getting new starts out of Congress in the two year time frame. He thinks that NASA has not been hit much harder than other agencies, and in fact thinks it has come out fairly well. He made the point that the budget has been dropping continuously for many years, and the relative importance of space science within the NASA budget has stayed constant, but that the overall cuts have affected it. He feels that the Europeans, although very mad over Solar/Polar, are still very interested in continued cooperation. That's all I can dredge out of my (and several others') memories. He seemed quite optimistic, and I guess I do too, after hearing him. Noel ------- ------------------------------ 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.