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Mars Global Surveyor Status Report January 19, 2000

Press Release From: Jet Propulsion Laboratory
Posted: Wednesday, January 19, 2000

Wednesday, January 19, 2000 (DOY 012/19:00:00 to DOY 019/19:00:00 UTC)
Launch / Days since Launch = Nov 7, 1996 / 1169 days
Start of Mapping / Days since Start of Mapping = April 1, 1999 / 293 days
Total Mapping Orbits = 3876
Total Orbits = 5558

Recent Events:

The mm011 sequence began execution on Jan 13 at 00:00 UTC and runs through Feb 4. The spacecraft continues to perform flawlessly in performing the nominal mapping mission.

The mz035 mini-sequence, containing scans for a third Pathfinder landing site image and two additional MPL landing site images finished execution on Jan 19 at 13:45 UTC. Unfortunately, bad luck struck again with regard to the Pathfinder opportunity and significant portions of the Pathfinder image were lost due to more Deep Space Network (DSN) problems. There is no redundant capability to return the imaging data at the high 40000 bps real-time rate and also record the data to the solid state recorders for redundant playback the next day. Consequently, return of these landing site images is a single opportunity event which requires the DSN stations to be configured and working properly during the ~30 minute data return period. Hardware, weather and other factors with the stations contribute to make this far from a foolproof process. In general, the DSN has performed excellently in supporting the MGS mission.

A change request was approved by the Project to perform some HGA motion calibration tests for the Magnetometer team. These will be performed on the dark side of the planet and will have minimal effect on normal operations. The only exception is that Radio Science ingress data will be prematurely truncated on the calibration orbits. These HGA motions tests will be performed over 15 orbits, with the solar arrays being moved to different fixed positions during the HGA motions after every three orbits. Due to mini-sequence buffer size constraints, the 15 orbits will be performed in two parts. The mz036 mini-sequence was successfully transmitted to the spacecraft on Jan 19, to perform the first 9 orbits on Jan 20 and mz037 will be transmitted on Jan 21 to perform the remaining 6 orbits on Jan 21. The Ka Band Link Experiment (KaBLE) was turned off on Jan 14, to reduce the spacecraft power loads. The KaBLE investigators are not currently utilizing the Ka Band data.

HGA Anomaly:

The HGA inner gimbal continues to decrease and is currently at 48.9 degrees. The inner gimbal angle will continue decreasing, reaching the location of the gimbal obstruction at 41.5 deg in early February. A special review was held on Jan 18 to discuss possible spacecraft testing to determine if the obstruction is still present. The recommendations from the review are expected by the end of the week. Any spacecraft testing would be performed over the next two weeks, prior to the start of beta supplement mapping operations.

Spacecraft Health:

All subsystems are reporting nominal health. A third Payload Data System (PDS) reset occurred on Jan 16. The reset data has been sent to JPL, who designed and built the PDS. The spacecraft team has been unable to correlate the data to any specific spacecraft activity.

Uplinks:

There have been 27 uplinks to the spacecraft during the last two weeks, including new star catalogs and ephemeris files, instrument command loads, KaBLE turn off and the mz036 mini-sequence load. Total command files radiated to the spacecraft since launch is 4345.

Upcoming Events:

The preliminary first beta supplement sequence will begin development Jan 20 in preparation for the start of beta supplement mapping operations on Feb 5. Additional MPL and MPF imaging opportunities will continue through Feb 4. The next imaging mini-sequence will be built on Jan 21 and will contain all the desired over-flight opportunities through Jan 26.

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