Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!ittvax!dcdwest!sdcsvax!sdcrdcf!hplabs!sri-unix!OTA@S1-A.ARPA From: OTA@S1-A.ARPA Newsgroups: net.space Subject: spool Message-ID: <663@sri-arpa.UUCP> Date: Fri, 3-Aug-84 04:55:00 EDT Article-I.D.: sri-arpa.663 Posted: Fri Aug 3 04:55:00 1984 Date-Received: Sun, 5-Aug-84 08:11:39 EDT Lines: 62 From: Ted AndersonDate: 2 Aug 1984 8:49-PDT From: dietz%USC-CSE@ECLA To: redford@shorty cc: space@MIT-MC.ARPA Subject: Re: How Does Geostar Work? Geostar works by triangulation. A signal addressed to a portable tranceiver is sent from the central ground station via one of the satellites. The ground unit then emits a very short omnidirectional microwave pulse (with ID information included). All four satellites receive this pulse, and transmit it back to the ground station. Time delays are used to compute position. The position is then transmitted back to the ground unit. The Geostar ground unit is simply a microwave tranceiver capable of emitting high power (500 watts, I believe) short duration pulses, along with some fast control logic to detect when the unit is being polled and to receive and display position information. Average power consumption is low, because the pulses are so short (a microsecond?). The Navstar system uses passive ground units, since they must operate in combat conditions where radio silence is critical. These passive units must do the triangulation themselves, so they are expensive. Paul Dietz dietz%usc-cse@usc-ecl ------------------------------ Date: 2 Aug 1984 14:41:29-EDT From: Hank.Walker at CMU-CS-UNH Subject: tethered satellite stories A recent one is "Tank-Farm Dynamo" by David Brin in the November 1983 Analog. A space station is created out of two groups of shuttle external tanks connected together by cables. Shuttles take advantage of the fact that the lower platform is moving slower than orbital velocity by "landing" on it and transfering their payload. The dynamo effect of a cable moving through magnetic fields is used to pump energy into the stations orbit to compensate for atmospheric drag. ------------------------------ Date: Thu, 2 Aug 84 10:51:41 pdt From: David Smith Message-Id: <8408021751.AA01896@HP-MARS> To: space%mc@csnet-relay.arpa Subject: Apollo 2-6 Cc: dsmith@csnet-relay.arpa Source-Info: From (or Sender) name not authenticated. The spacecraft which burned on the pad was known as Apollo 204 for some reason. I think (but am not at all sure) it was also counted as Apollo 4. One unmanned Apollo was lofted into a high suborbital trajectory, then rammed into the atmosphere at 25000 mph to test the heat shield. David Smith dsmith%hp-labs@csnet-relay ...!ucbvax!hplabs!dsmith Formerly at Cmu-cs-ius.arpa ------------------------------ End of SPACE Digest *******************