Mars Global Surveyor Status Report 12 Dec 2001

Wednesday, December 12, 2001 (DOY 339/19:00:00 to DOY 346/19:00:00 UTC)

Launch / Days since Launch = Nov. 7, 1996 / 1862 days

Start of Mapping / Days since Start of Mapping = April 1, 1999 / 986 days

Total Mapping Orbits = 12,354

Total Orbits = 14,037

Recent Events:

Background Sequences – The spacecraft is operating nominally in performing
daily recording and transmission of science data. TES and MOC images are
being supplied to the Mars Odyssey team to support their aerobraking
campaign. The MM155A sequence has performed well since it started on 01-318
(11/14/01). It terminates on 01-347 (12/13/01). MM156A starts tonight at
01-346 (12/12/01), 23:57 SCET UTC.

Other – Roll Only Targeted Observations (ROTOs) have been suspended to
reduce the probability of entering C-Mode during Mars Odyssey aerobraking.
The Spacecraft Team continues to investigate MGS difficulties in star
processing following slew maneuvers like ROTOs. The team is designing tests
and identifying steps needed to mitigate C-mode entry following ROTOs. MGS
has completed 207 ROTOs to date.

The MZ147 High-rate Gyro Data Collection mini-sequence executed successfully
on 01-345 (12/11/01). The MZ148 contingency mini-sequence was uplinked, then
terminated as planned due to the success of MZ147. The data show that the
high-rate gyro bias estimates used during the September and October ROTOs
would not have caused the loss of attitude knowledge that resulted in C-mode
entry.

Spacecraft Health:

All subsystems report good health and status.

Uplinks:

There have been 17 uplinks to the spacecraft during the past week, including
new star catalog and ephemeris files, instrument command loads, and the
High-rate Gyro Data Collection mini-sequences cited above. 6,022 command
files have been radiated to the spacecraft since launch.

Upcoming Events:

MGS will continue to support the Odyssey mission during the aerobraking
phase by supplying TES and MOC images of the Martian surface. Martian dust
storms can bloom into the upper atmosphere, significantly increasing the
atmospheric density and posing a threat to Odyssey. The MGS images will
provide the Odyssey team the opportunity to avoid the dust storms if they
occur.