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Mission Status 2009
Kevin V. Gilliland Stardust Spacecraft Team
September 16, 2009
All subsystems are nominal. Stardust had two passes in the past week: Thursday, September 10, and Monday, September 14. The next will be Tuesday, October 6. During Thursday's pass, all small forces data packets were received and processed successfully. Attitude control is provided by string 2 thrusters. The trend in thruster pulse commands shows the deadbanding is performing efficiently. Each day, Stardust fires its RCS-5 and RCS-8 thrusters approximately 120 times, and its RCS-6 and RCS-7 thrusters are fired approximately 30 times. Several star camera outages have occurred in the past month, while the star camera was pointed toward the constellation Capricorn. None of the outages were longer than 10 seconds, indicating the camera was able to immediately determine a solution in the next processing cycle. The outages are likely due to a bright object not in the star catalog. Control error counts were also observed during the previous month, which occasionally occur in the course of normal deadbanding. The counts occurred out of contact, so AACS telemetry for analysis is sparse. Given that the error counts are near the star camera outages and were seen only in the Z-axis, it is likely that the same bright object allows for increased noise in the Z-axis rate estimate. Consecutive rate estimates of opposite sign would result in unnecessary Z-axis thruster firings. The control error counts occurred for no more than 12 seconds, well below the 35 second threshold. Stardust is now 1.68 AU (approximately 156 million miles) from the Sun. Background sequence SN029 is executing now.
July 16, 2009
All subsystems are nominal.Stardust had its monthly pass on Tuesday July 15 and the next scheduled pass is on August 12th and 14th. During the pass we loaded the next background sequence (sn027) and the commands to perform a calibration of thrusters firing at the Tempel 1 approach attitude. In order to better estimate our fuel usage during the approach to Tempel 1 we will maneuver the spacecraft into the approach attitude, on August 5, and dwell there for two days to collect the thruster usage telemetry. We chose this date becasue the spacecraft to sun distance (1.6 AU) is similar to the Tempel 1 approach (December 2010) and will provide an excellent prediction of the fuel usage. Background sequence SN026 is executing now. Sequence SN027 is on board, and will become active Sunday, August 10th.
