Mars Global Surveyor Update 7 Feb 2001
Mars Global Surveyor Status Report
Wednesday, February 7, 2001 (DOY 031/19:00:00 to DOY 038/19:00:00 UTC)
Launch / Days since Launch = Nov. 7, 1996 / 1554 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 678 days Total Mapping Orbits = 8,575
Total Orbits = 10,258
Recent Events:
Background Sequences — The spacecraft continues to operate nominally in performing the beta-supplement daily recording and transmission of science data. The mm110 sequence executed successfully from 01-032 (2/1/00) through 01-034 (2/3/01). The mm111 sequence has performed well since it started on 01-035 (2/4/01). It terminates on 01-038 (2/7/01). The mm112 sequence, successfully uplinked on 01-037 (2/6/01), begins executing on 01-039 (2/08/01).
Other – Another successful DDOR experiment was performed on 01-034 (2/3/01) as part of the mm110 background sequence.
Spacecraft Health:
All subsystems report nominal health. Investigation into the root cause of the X-axis Reaction Wheel failure continues. Although we are confident that a short circuit within the RWA-X electronics caused the failure, isolating the exact piece-part that failed seems unlikely. Work continues in identifying operational impacts associated with using RWA-S for attitude control. We are also investigating methods of protecting the spacecraft against a second RWA failure.
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 background sequences cited above. We also increased the Momentum Unload Give Up Timer to 120 minutes so that manually induced momentum unloads do not terminate prematurely due to worst-case phasing errors. (See the 1/24/01 MGS Status Report) Finally, we reset the Audit Queue Counter to a value consistent with the Audit Queue activity that occurred since the counter reached its maximum value of 255. This particular counter does not rollover automatically and must be reset with a ground command when it reaches its maximum value. There have been 5,113 command files radiated to the spacecraft since launch.
Upcoming Events:
The mm113 background sequence will be uplinked on 01-040 (2/09/01). Development of the mz072 Roll Only Targeted Observation (ROTO) Demonstration mini-sequence will commence on 01-043 (2/12/01).
