STARDUST Status Report

May 28, 1999

The STARDUST spacecraft and subsystems continue to perform nominally as flight sequence SC005 started on Tuesday when the spacecraft was 1.4 AU from the Sun and 0.4 AU from Earth. Both the University of Chicago Dust Flux Monitor Instrument (DFMI) and the Max Planck Institute Cometary and Interstellar Dust Analyzer (CIDA) continue to be pointed into the interstellar dust stream.

With only one communication session per week, the flight team at Lockheed Martin Astronautics (LMA) determined that CIDA had rebooted itself late last week and was operating nominally within its rebooted state, which is not its operational state. During the communication session, sufficient time was not available to transmit all CIDA data down and the data around the time of reboot still remains on the spacecraft. Commands will be sent to download the remaining CIDA data and also set CIDA back to its operational mode late next week.

LMA also observed that the Solid State Power Amplifier (SSPA) started to show signs of trapped charges again where the SSPA exhibits low amplitude variations in gain and temperature (~2 dB in signal strength and 4 degrees C), within nominal operating values. Concern exists that over the 7 year mission lifetime this behavior could reduce the reliability of the SSPA. The project is therefore considering powering off the SSPA during non-contact time periods (over 90% of the time) starting in flight sequence SC006, allowing the trapped charges to dissipate as was successfully done previously by power cycling the SSPA.

A team of DFMI, LMA and JPL experts was formed to analyze the DFMI anomalous behavior which occurred a few weeks ago after which the DFMI was powered off and remains off. The symptoms of the DFMI behavior resemble a "galloping" power converter which causes large amplitude and high frequency changes to the output power. Detail circuit modeling studies and tests of the engineering unit in a varying thermal environment are underway. The DFMI operated nominally for 2 months at near room temperature. The temperature dropping to -20 degrees C a few weeks ago when the spacecraft was turned to point DFMI and CIDA into the interstellar dust stream. At the present time the anomalous behavior of the DFMI performance has not been tied to this large temperature change, but this is under study.

Near-term activities for the next few months include setting CIDA back to its operational state, turning the DFMI and Navigation Camera back on, and going to all stellar attitude.

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