Mars Global Surveyor Status Report 18 Apr 2001

Mars Global Surveyor Status Report

Wednesday, April 18, 2001 (DOY 094/19:00:00 to DOY 108/19:00:00 UTC)

This report covers two weeks.

Launch / Days since Launch = Nov. 7, 1996 / 1624 days

Start of Mapping / Days since Start of Mapping = April 1, 1999 / 748 days

Total Mapping Orbits = 9,444

Total Orbits = 11,127

Recent Events:

Background Sequences — The spacecraft continues to operate nominally in
performing the beta-supplement daily recording and transmission of science
data. The mm128, mm129, and mm130 sequences executed successfully from
01-095 (4/05/01) through 01-104 (4/14/01). The mm131 sequence has performed
well since it started on 01-105 (4/15/01). It terminates on 01-108
(4/18/01). The mm132 sequence, successfully uplinked on 01-107 (4/17/01),
begins executing on 01-109 (4/19/01).

Other – MGS successfully performed twelve Radio Science Occultation Egress
Scans on 01-095 (4/5/01) and 01-096 (4/6/01). They were contained in the
mz085 mini-sequence. MGS has performed 65 Roll Only Targeted Observations to
date.

Spacecraft Health:

All subsystems report nominal health.

Uplinks:

There have been 30 uplinks to the spacecraft during the past two weeks,
including new star catalogs and ephemeris files, instrument command loads,
the background sequences cited above, a thruster accumulator reset command,
and ROTO mini-sequences mz086 through mz090.

Commands were uplinked to modify the Reaction Wheel Assembly fault
protection software and associated scripts. The modified response will allow
a quicker recovery should another reaction wheel fail.

The first of three solar array position management scripts was modified to
offset the commanded solar array positions by 25 degrees. Our goal is to
extend the life of the Partial Shunt Assemblies by reducing the amount of
excess power generated by the solar arrays. We will update the other two
scripts after verifying the expected spacecraft performance under the first
script.

There have been 5,258 command files radiated to the spacecraft since launch.

Upcoming Events:

The mm133 background sequence will be uplinked on 01-110 (4/20/01). On
01-115 (4/25/01) of that sequence, MGS will transmit high frequency
spacecraft body rate data to Earth. The data will provide insight into the
health of the -Y solar array hinge and the effects of solar array motion on
TES data. MOC Defocus Calibration Scans will be performed by the mm134 and
mm135 sequences between 01-116 (4/26/01) and 01-123 (5/02/01). Radio Science
Occultation Egress Scans are scheduled for 01-132 (5/12/01) and 01-133
(5/13/01).

ROTO mini-sequences mz090 and mz091 will execute this next week.