Stardust Status Report 6 October 2000

During the only scheduled Deep Space Network (DSN) tracking pass on
Wednesday October 4th, the signal from the STARDUST was suddently lost
at 16:37:40 (UT) when it entered safe mode. The following day
at 16:48:23 (UT), the signal from the spacecraft was re-acquired, as
anticipated, when the spacecraft started its daily safe mode transmission.
Early analysis of the data showed the safe mode cause was due to attitude
knowledge loss. Based on the real time telemetry that showed all systems
performing normally, the decision was made to exit safe mode prior to the
end of the three hour communication pass. At 19:20 (UT) the command to exit
safe mode was executed by the spacecraft. By the end of the Deep Space
Network (DSN) pass (21:30 UT), the preliminary estimate for the safe mode
entry remained the same. The safe mode entry has the characteristics of
the Payload Attitude Control Interface (PACI) board reset that caused two
previous safe mode entries last July/August. However, the data indicates
that there was no PACI reset this time during the entire episode.
Investigation into the root cause is ongoing and will require some time to
determine. The spacecraft was configured at the end of yesterday’s DSN
pass to use the Medium Gain antenna to point at Earth in a six degree
deadband, with the Telecommunications Subsystem powered on, and using
Gyro Based attitude determination (Inertial Measuring Units are powered on).

During the DSN pass today (Friday October 6th) commands were sent to
restart the current flight sequence, return the spacecraft to Sun point
and power off the Telecommunications Subsystem to return the spacecraft to
its normal operation. The IMUs will remain on until a better understanding
of the root cause of the safe mode entry is known. The current flight
sequence will command the spacecraft to communicate at the next
regularly scheduled time on Wednesday October 11th.

For more information on the STARDUST mission – the first ever
comet sample return mission – please visit the STARDUST home page: