Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site ssc-vax.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!hao!hplabs!intelca!qantel!dual!zehntel!zinfandel!ihnp4!houxm!vax135!cornell!uw-beaver!ssc-vax!eder From: eder@ssc-vax.UUCP (Dani Eder) Newsgroups: net.space Subject: Re: More on Satellite Retrieval Message-ID: <174@ssc-vax.UUCP> Date: Mon, 29-Oct-84 11:53:52 EST Article-I.D.: ssc-vax.174 Posted: Mon Oct 29 11:53:52 1984 Date-Received: Wed, 7-Nov-84 00:45:52 EST References: <11810@sri-arpa.UUCP> Organization: Boeing Aerospace Co., Seattle, WA Lines: 39 > While we're all wondering about some details of the satellite recovery > schedule for the next shuttle mission, I'd like to add my own wonders: > > What are the constraints on the rendezvous? According to the PBS show, > the satellites are in quite an elliptical orbit. I got the impression > The satellites were placed in elliptical orbits by the first of two solid motors that were to be used in their original delivery. The second, smaller, motors were fired months ago, and placed the satellites about 600 km high (if memory serves me). The Hughes model 376 satellites carry fuel used to keep them in position or move about in GEO. This fuel was recently used to move the satellites down to an altitude the Shuttle Orbiter can reach. > How dangerous is all this? Probably less dangerous than the delivery of the new satellites which will also occur on this mission. The new ones carry 8000 lbs of very energetic propellants each. The old satellites have burnt out their motors, which means no fuel is left. Someone in another article asked why the RMS is being used to recover the satellites rather than the astronauts directly, and whether the satllites are spinning fast. The satellites mass 1000 lbm each. Even though they 'weigh' nothing, that mass still has to be pushed around. The nearest equivalent I can think of is pushing a boat around a dock by hand. At low speeds this is nearly frictionless in two dimensions. The astronauts are in these bulky suits, too boot. While it could be done, it is much easier to use the electrically powered RMS. The satellites will have been spun down to less than one RPM before the astronauts get to them. Once the stinger is firmly attached to the satellite, the astronaut merely pushes the 'stop' button on his Manned Maneuvering Unit. The MMU calculates which thrusters to fire to stop the residual spin. Dani Eder / Boeing Aerospace Company / ssc-vax!eder /(206)773-4545 *** REPLACE THIS LINE WITH YOUR MESSAGE ***