From: Andy Calloway [Andy.Calloway@gsfc.nasa.gov]
Sent: Wednesday, August 25, 1999 7:51 PM
To: John.Hall@msfc.nasa.gov; Steve.Goodman@msfc.nasa.gov
Cc: CShoemak@pop500.gsfc.nasa.gov; EWeidner@pop500.gsfc.nasa.gov;
jkowalsk@pop500.gsfc.nasa.gov; AKludze@pop500.gsfc.nasa.gov
Subject: LIS HEATER AUTO CONFIG

To all:

On 99/237  at 22:12:30, the LIS Heater Auto Select function powered Off the
Primary Heater configuration and Powered On the Secondary Heater
configuration.   Trending shows that the LIS Filter Heater temperatures
(LFLTHTRAT & LFLTHTRBT) appeared to be in the nominal low range at the time
(approx 25.3° and 24.7° respectively).  VIRS experienced a VIRS warning
message at the time, and it's being verified whether the spacecraft was
over the SAA at the time.  Some form of ESD or high energy particle hit
could have been responsible for the action.  With the backup heater on, the
temperatures increased soon thereafter by a little over .5 degree.  The
temperatures are still well below the Yellow High and Red High limits of
30° and 33°.  We do not anticipate returning manually to the primary heater
configuration until we receive confirmation and authorization from MSFC,
since the temperatures are holding.  The console crew has been informed,
however, to immediately notify the on-call staff if any problems arise with
the secondary heater, and the both_heaters_failed flag trips.  We will of
course verify any planned commanding with MSFC tomorrow.  Thank you for
your cooperation.

Andy Calloway

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_/_/	E-Mail Address:        Andy.Calloway@gsfc.nasa.gov
_/_/	NASA  Goddard Space Flight Center     Greenbelt MD
_/_/	TRMM:  Tropical Rainfall Measuring Mission
_/_/	Spacecraft Systems Engineer   Flight Operations Team
_/_/	Phone:  Desk: (301) 614-5543  MOR: 286-0197
_/_/	Pager: (301) 708-8274  Fax: (301) 614-5266
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