Mars Global Surveyor Update – November 14, 2001

Mars Global Surveyor Status Report

Wednesday, November 14, 2001 (DOY 311/19:00:00 to DOY 318/19:00:00 UTC)

Launch / Days since Launch = Nov. 7, 1996 / 1834 days

Start of Mapping / Days since Start of Mapping = April 1, 1999 / 958 days

Total Mapping Orbits = 12,011

Total Orbits = 13,694

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 MM154B sequence has performed well since it started on 01-295
10/22/01). It terminates on 01-319 (11/15/01). MM155A starts tonight at
01-318 (11/14/01), 23:57 SCET UTC.

Other – Roll Only Targeted Observations (ROTOs) have been suspended to
reduce the probability of entering C-Mode during the initial stages of Mars
Odyssey aerobraking. The C-Mode investigation continues. Its purpose is to
determine the root cause of the latest C-Mode entry and identify risk
mitigation steps that will allow MGS to resume ROTO operations during
Odyssey aerobraking. MGS has completed 207 ROTOs to date.

The Sun Monitor Ephemeris fault detection was re-enabled with updated
parameters. The new parameters will prevent transient shadowing of the sun
sensors from triggering C-mode entry and allow additional C-mode protection
if attitude knowledge becomes corrupted.

Spacecraft Health:

All subsystems report good health and status. The spacecraft team is
investigating the spacecraft’s difficulty in processing stars leading to the
C-Mode entry.

Uplinks:

There have been 12 uplinks to the spacecraft during the past week, including
new star catalog and ephemeris files, instrument command loads, and the
MM155 background sequence. 5,962 command files have been radiated to the
spacecraft since launch.

Upcoming Events:

MGS will continue to support Odyssey during the aerobraking phase of the
Odyssey mission 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.