Terra Weekly Mission Status Update

Weekly Update Archive

February 25 - March 3, 2005

The Terra spacecraft is operating nominally in science mode. Terra successfully performed a minus 16.99-degree Roll Maneuver for MODIS calibration purposes during this period.

MMS ATC late change build issues occurred on Feb. 24-25, 2005. When built, multiple loads were created simultaneously which gave undesirable results. The MMS Systems Engineer in both cases successfully performed a work around. However, the work around is risky and can potentially delay the ATC from being loaded by the 20:00z boundary where instrument safe commands are issued. Until further notice, no late changes are being generated unless critical for spacecraft. Raytheon Denver is investigating.

MMS ATC drop command status: Last occurrence has been on February 18. Since then, the problem has been isolated and a patch developed. Delivery of patch may be delayed until other late change issues are resolved.

Spacecraft Activities/Anomalies/Issues: MIR= Mission Impact Report
Two MIRs occurred this week having to do with the High Gain Antenna Motor Drive Assembly (MDA2) BITE failures while in the South Atlantic Anomaly (SAA). In both cases, there was no impact to science objectives and no data loss.

Ground System and Data Processing System Anomalies/Issues:
One MIR occurred this week having to do with a late acquisition with TDW. There was no impact to current science objectives and no science data loss.

One MIR occurred this week during an X-band EPGN proficiency contact with Datalinks/PF1. There was an unusually high number of X-band dropouts with 5285 uncorrectables and 160 lost frames. Since this contact used old science data, there was no impact to current science objectives.

One MIR occurred this week during an X-band EPGN proficiency contact with TNOC/SKS. Two old science replays were attempted. The front-end processor failed to lock on data for both replays. Since this contact used old science data, there was no impact to current science objectives.

One MIR occurred this week involving mutual interference at AOS. Two forward re- acquisitions were needed to acquire spacecraft resulting in a roughly 4-minute delay in AOS. There was no impact to current science objectives and no science data loss.

One MIR occurred this week where EDOS was not configured properly to capture science data via an EPGN contact. Only giving EDOS 2 minutes to switch from the previous TDRS contact to this EPGN contact probably did not help matters. In any event, 95% of MISR data was captured on the next pass. Therefore, there was a 5% loss (440 EDUs) of MISR data. No other science data was lost.