Aucbvax.4575 fa.space utzoo!decvax!ucbvax!space Wed Oct 21 04:35:51 1981 SPACE Digest V2 #17 >From OTA@S1-A Wed Oct 21 04:00:26 1981 SPACE Digest Volume 2 : Issue 17 Today's Topics: Carbonless plastics Peaceful Uses of Rocks Cosmos Radiation pressure SPS vs. Fusion - A response to REM / counterresponse Begg talk at Hahvahd ---------------------------------------------------------------------- Date: 20 Oct 1981 1124-PDT Sender: BILLW at SRI-KL Subject: Carbonless plastics From: William "Chops" Westfield To: space at MC Cc: billw Message-ID: <[SRI-KL]20-OCT-81 11:24:02.BILLW> Aren't the silicones all carbonless ? (basically polymerized sand, I think...) Furthermore dont silicones offer all sorts of advantages over most other plastics in harsh envirenments ? (Things like ability to withstand high temperature extremes, lack of vloitile to boil off, and so on ?) Bill W ------------------------------ Date: 20 Oct 1981 1409-PDT From: Paul Dietz Subject: Peaceful Uses of Rocks To: space at MIT-MC cc: ota at S1-A, jef at LBL-UNIX There has been a discussion on ARMS-D about the military potential of the SPS. It was pointed out that if you can build an SPS you can also drop large masses onto your enemy. Dropped from infinity, 1 ton of rock = 60 tons of TNT, so a 4 meter spherical asteroid yields 60 KT (thanks to OTA for these figures). There have been proposals for using nuclear explosives for peaceful purposes (digging canals and such). These efforts were scuttled by the test ban treaty. Using asteroids we can get around the problem of radioactive fallout, not to mention the savings in fissile material. This illustrates that there is an additional energy source in space: gravitational potential energy. Is there an easy controlled way of extracting this energy? ------- ------------------------------ Date: 20 Oct 1981 16:51:11-PDT From: vax135!hocsb!dcs at Berkeley FROM: d.c.smith TO: vax135!ucbvax!space@Berkeley DATE: 10/20/81, 12:38 PM SUBJECT: Cosmos Can anyone tell me if Carl Sagan's series "Cosmos" can be purchased on videotape? ------------------------------ Date: 20 October 1981 22:58-EDT From: Gene Salamin Subject: Radiation pressure To: SPACE at MIT-MC For a beam of light, the radiation pressure P (in Newtons/meter^2) is given by U/c, where U is the intensity (in Watts/meter^2) and c = 3.0e8 meters/second is the speed of light. Taking the intensity as 1 kW/m^2, the pressure is 3.3e-6 N/m^2. This ignores the pressure of solar wind. The radiation beamed down by an SPS produces a recoil, but since only 10% or so of the incident solar energy gets into the beam, the recoil force is only 10% of the incident force. ------------------------------ Date: 21 October 1981 03:53-EDT From: Jerry E. Pournelle Subject: SPS vs. Fusion - A response to REM / counterresponse To: REM at MIT-MC cc: SPACE at MIT-MC, DIETZ at USC-ECL MOONROCKS CAN BE SIMULATED TO ANY DEGREE OF SIMILARITY YOU WANT, AND IN VERY LARGE QUANTITIES; PROCESSING HAS BEEN DONE ON SIMULACRA ------------------------------ Date: 21 October 1981 04:04-EDT From: Jerry E. Pournelle Subject: Begg talk at Hahvahd To: JNC at MIT-XX cc: SPACE at MIT-MC, mph at MIT-XX, ludwig at MIT-XX, wayne at MIT-XX I TTO AM and have been impressed with Beggs, and with his Deputy Hans Mark. When Beggs made his first public appearance as Administrator at an AIAA convention, I overheard someone in the audience say "Jeez, we got a philosopher for an administrator..." As to public acceptance of space, it's mostly that they are finally becoming AWARE of public activities and public interest; washington doesn't listen to the nation, but it does read its mail. The L-5 campaigns have been very effective. Note also that in a few short years the idea of lunar mines in this century hs become an acceptable goal. Please excuse the horrid typing. I get NO feedback on this loop in the net; the lines are very flakey, and will be for a while until I can get a new 1200 baud system and operate on a different TIP. Thanks for puttin up with the noise. ------------------------------ 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.