STARDUST Status Report

August 6, 1999

During the scheduled STARDUST Deep Space Network (DSN) pass on Wednesday, August 4, it was discovered that the spacecraft was in safemode. After approximately an hour of waiting for a signal, commands were transmitted to the spacecraft to power on the Exciter and Solid State Power Amplifier (SSPA). This resulted in a weak signal and carrier lock being detected from the spacecraft at the DSN tracking station. Following this, commands were then sent to deadband walk the spacecraft to Medium Gain Antenna (MGA) Earth point with a resulting increase in signal strength. Further commands were transmitted to start telemetry download from the spacecraft, and it was then confirmed that a reboot had occurred on July 30, approximately 2 hours after the last DSN pass. Event Reports (EVRs) were obtained from the spacecraft and the apparent cause is very similar to the last safemode entry about 2 weeks ago. Commands were sent to exit safemode and restore the spacecraft to its normal configuration. Presently, the spacecraft configuration is Nominal Mode, with uplink using the Low Gain Antenna #2 (LGA2), downlink using the MGA, SSPA1 powered on, and Earth pointed with 4 degree deadbands.

In both safemodes, the problem appears to be the same: the lack of Star Camera image transfer through the Payload and Attitude Control Interface (PACI) board. Both problems occurred within a day after normal communications. This tends to rule out an Single Event Upset (SEU) of the PACI board. Also, the problems seems to be unrelated to specific flight software patches for going to All-Stellar attitude control and also task priority swapping, which are in their final phases of Spacecraft Test Laboratory (STL) testing. Since the Cometary Interstellar Dust Analyzer (CIDA) instrument was not powered on during the second safing event, CIDA appears not to be a factor.

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