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From: starrfie@hydro.la.asu.edu (Sumner Starrfield) Subject: HERE'S LATEST WE HAVE ON MARS OBSERVER -- (fwd) Date: Mon, 23 Aug 93 10:32:32 MST Forwarded message: >From scowen@wfpc3.la.asu.edu Mon Aug 23 09:50:37 1993 From: scowen@wfpc3.la.asu.edu (Paul A. Scowen) Message-ID: <vsnet-history1382@hoge.baba.hajime.jp> Subject: HERE'S LATEST WE HAVE ON MARS OBSERVER -- (fwd) To: astro@BigBang Date: Mon, 23 Aug 93 9:49:17 MST X-Mailer: ELM [version 2.3 PL11] Forwarded message: From: malin@helium.msss.com Subject: Re: Mars Observer Communications Failure Not with a bang but a wimper.... As of 0730 PDT Monday, the S/C is still out of communications. The thinking for the last 30 hrs or so is that the S/C is functioning nominally except for the transmitter, which has somehow gotten into a state in which it is not broadcasting. Many different attempts have been made to reset it in different ways. The MOI sequence is on-board and was executing nominally at loss of signal (which was planned--they turn off the TWT so that the shock of the pyro doesn't break the heated filament). AOS never occurred. MY best guess (personal view, not that of the Project) is that MOI will occur tomorrow, the spacecraft will re-establish itself in array normal spin, sit calmly waiting for us to communicate with it, and on Wednesday default into safe mode when it doesn't hear from us. At that time, it should switch autonomously to the low gain antenna and emergency low rate data mode, which should be seen here easily. My personal concern is whether the attitude of the burn will be correct (i.e., whether the AACS has worked well enough to get us into the right orbit). Of course, the other extreme is that the spacecraft will not execute the MOI maneuver (either its been destroyed, safed itself without going into low-rate mode, or something else). I'll try to keep you guys posted. MM -- ------------------------------------------------------------------------------- Paul A. Scowen INTERNET: scowen@wfpc3.la.asu.edu Department of Physics & Astronomy paul.scowen@asu.edu Arizona State University DECnet: PHYAST::SCOWEN Box 871504 Bitnet: scowen@asu Tempe, AZ 85287-1504 USA -------------------------------------------------------------------------------
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