Mars Global Surveyor Status Report 11 Sep 2002
Wednesday, September 11, 2002 (DOY 247/19:00:00 to DOY 254/19:00:00 UTC)
- Launch / Days since Launch = Nov. 7, 1996 / 2135 days
- Start of Mapping / Days since Start of Mapping = April 1, 1999 / 1260 days
- Total Mapping Orbits = 15,693
- Total Orbits = 17,376
Recent Events:
Background Sequences – The spacecraft is operating nominally in performing the beta-supplement daily recording and transmission of science data. The mm207 sequence executed successfully from 02-248 (9/05/02) through 02-250 (9/07/02). The mm208 sequence has performed well since it started on 02-251 (9/08/02). It terminates on 02-254 (9/11/02). The mm209 sequence, successfully uplinked on 02-253 (9/10/02), begins executing near the end of day on 02-254 (9/11/02).
Other – Three Roll Only Targeted Observations (ROTOs) were performed successfully by the mz199 minisequence. The two ROTOs contained in mz198 were not executed because mz198 could not be uplinked. Difficulties at the DSN station prevented successful uplink of the requisite payload command files. MGS has completed 299 ROTOs to date.
Flight software was successfully updated to ensure that MGS telemeters correct equator-crossing times when it is in the CSA Backup AACS mode and nadir pointed. MGS recently began managing system momentum by periodically maneuvering between the relay-16 attitude and the nadir attitude. While effectively reducing propellant consumption, this new method of managing system momentum opened a small window of vulnerability where equator-crossing times would be computed incorrectly. The flight software patch effectively eliminates this vulnerability.
Spacecraft Health:
Spacecraft subsystems report good health and status.
Uplinks:
Twenty-two of thirty command files were successfully uplinked to MGS during the past week. DSN station related timing anomalies in the uplink path resulted in MGS properly rejecting seven command files. The successful uplinks included new star catalog and ephemeris files, instrument command loads, the mi0644 equator crossing flight software patch, the mz199 ROTO mini-sequence, and the mm208 and mm209 background sequences. 7,017 command files have been radiated to the spacecraft since launch.
Upcoming Events:
ROTOs are planned for next week in the mz200 and mz201 mini-sequences. Radio Science Occultation Egress Scans will be performed on 02-273 (9/30/02) and 02-274 (10/01/02). A DDOR experiment is scheduled for 02-276 (10/03/03).
