Mars Global Surveyor Status Report 26 Sep 2001

Mars Global Surveyor Status Report

Wednesday, September 26, 2001 (DOY 262/19:00:00 to DOY 269/19:00:00 UTC)

Launch / Days since Launch = Nov. 7, 1996 / 1785 days

Start of Mapping / Days since Start of Mapping = April 1, 1999 / 909 days

Total Mapping Orbits = 11,412

Total Orbits = 13,095

Recent Events:

Background Sequences – The spacecraft is operating nominally in performing
daily recording and transmission of science data. The mm153 sequence has
performed well since it started 01-256 (9/13/01). It terminates on 01-290
(10/17/01).

Other – Delta-DOR experiments were performed on 01-267 (9/24/01) and 01-269
(9/26/01).

No Roll Only Targeted Observations (ROTOs) were performed this past week.
ROTOs were temporarily suspended pending investigation of the C-Mode entry
root cause. MGS entered C-Mode on 9/6/01 because the STAREX star processing
software could not converge on a good inertial attitude following a ROTO.
The ROTO did not cause the C-Mode entry, but STAREX performance following
ROTOs may impact how we perform ROTOs in the future. MGS has completed 198
ROTOs to date.

Spacecraft Health:

All subsystems report good health and status. The spacecraft team is
investigating ways to improve the probability that STAREX will converge on a
good inertial attitude following each ROTO. The MOLA instrument team is
still investigating the MOLA anomaly of 01-181 (6/30/01) and will be
requesting a fifth diagnostic test in the near future.

Uplinks:

There have been 16 uplinks to the spacecraft during the past week, including
new star catalogs and ephemeris files, instrument command loads, and the
MZ136A ROTO mini-sequence. 5,771 command files have been radiated to the
spacecraft since launch.

Upcoming Events:

On 01-270 (9/27/01), MGS will perform a ROTO during a communications orbit
for the first time. Previously, MGS had been restricted to performing ROTOs
only during non-communications orbits. Two more ROTOs during communications
orbits are scheduled for the MZ037 mini-sequence.

A Solar Array (SA) and High Gain Antenna (HGA) flexible modes baseline
diagnostic test will be performed on 01-278 (10/05/01). It is designated
MZ139. Performing this test periodically should give us insight into any
additional SA hinge or HGA gimbal degradation, if it occurs.