Xref: cantaloupe.srv.cs.cmu.edu sci.space:61187 sci.astro:34975 sci.physics:51862 Newsgroups: sci.space,sci.astro,sci.physics Path: cantaloupe.srv.cs.cmu.edu!magnesium.club.cc.cmu.edu!news.sei.cmu.edu!cis.ohio-state.edu!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!saimiri.primate.wisc.edu!eng.ufl.edu!usenet.ufl.edu!mailer.cc.fsu.edu!geomag!cain From: cain@geomag.gly.fsu.edu (Joe Cain) Subject: Drag free satellites (was: Stephen Hawking Tours JPL) Keywords: JPL References: <23APR199317325771@kelvin.jpl.nasa.gov> <1raee7$b8s@access.digex.net> Followup-To: sci.space Sender: cain@geomag.gly.fsu.edu Organization: Florida State University Geology Dept. Date: Sat, 24 Apr 1993 20:57:25 GMT Message-ID: Lines: 23 In article <1raee7$b8s@access.digex.net> prb@access.digex.com (Pat) writes: >In article <23APR199317325771@kelvin.jpl.nasa.gov> baalke@kelvin.jpl.nasa.gov (Ron Baalke) writes: >> In answer >>to a question from Hawking, Chahine described a proposed >>drag-free satellite, but confirmed that at this point, "it's only >>a concept." > >SO what's a drag free satellite? coated with WD-40? I am puzzled by the term "concept." Drag free may already have been flown. It was the idea behind putting up a spacecraft that would more accurately respond to motions from the Earth's gravity field and ignore drag. It was proposed many years ago and involved a ball floating between sensors whose job it was to signal to little adjustment jets to keep the ball away from them. The ball itself would then be in a drag free condition and respond only to gravity anisotropies, whereas the spacecraft itself would be continuously adjusting its position to compensate for drag. Joseph Cain cain@geomag.gly.fsu.edu cain@fsu.bitnet scri::cain (904) 644-4014 FAX (904) 644-4214 or -0098