Terra Weekly Mission Status Update May 3 – 9, 2002

The Terra spacecraft is in nominal mode. All instruments are functioning
well in Science Mode.

The Flight Ops Team completed the NASA requested NPP 24-hour demonstration
on May 3. For the demo, the frequency of MODIS Science playbacks were
increased to twice per orbit.

The Flight Ops Team successfully performed a 19.0 second Drag Make Up
Maneuver on May 8. This was the second maneuver executed with the new
mode transition criteria. Maneuver and mode transitions were conducted as
expected.

The MODIS Instrument Operations Team successfully loaded a one-word patch
to the MODIS EEPROM on May 8. This patch will minimize the likelihood of
Survival Mode recovery problems due to Formatter resets which hindered
communications during the last recovery.

Analysis this week indicated that a Terra Science Formatter-A MODIS
Channel Overwrite Error occurred on April 21 for one telemetry sample.
The science data VCDU Header was overwritten due to an errant Direct
Memory Access in the HPM-2 Card. The MODIS Channel was the only channel
effected. The error is believed to be internal to the Science Formatter.
Telemetry has been nominal since. Investigation is ongoing.

Recent direct broadcast housekeeping playbacks performed have intermittent
data gaps. Cause unknown. Additional proficiency passes have been
scheduled with the Ground Network to help troubleshoot the problem.

There will be no MODIS roll maneuver in May due to the fact that lunar
geometry would require a roll angle greater than the maximum allowed by
the mission rules.

The Flight Ops Team will continue supporting a series of NPP latency dumps
to identify processing and transmission bottlenecks.