Stardust Status Report July 13, 2001
There was one Deep Space Network (DSN) tracking pass in the past week.
All subsystems are performing normally.
The Cometary and Interstellar Dust Analyzer (CIDA) instrument continues
to observe the interstellar dust stream with an optimal spacecraft
attitude when not in communication with Earth.
The remaining Navigation Camera guide star images were downlinked. These
images looked at the exact star field that will be behind Comet Wild 2,
2.5 years from now. Before launch, it was expected that the longest effective
exposure would be about 1 second, limited by attitude rates being 1 pixel
per second or larger. Based upon these rates, it was expected that a
perfect, uncontaminated navigation camera could see as star as dim as about
10.5 visual magnitude. We were pleased to see that the lowest attitude rate
is 10 times less than predicted. Also, in one five-second exposure guide
star image, at least 90 stars were identified the dimmest was as low as
11.7 visual magnitude. There are many more star-like images that were not
identified. These could be stars dimmer than 11.7 magnitude, since the star
catalog that was used only went down to 11.7 visual magnitude.
The power subsystem engineers have been conducting tests of the spare
flight battery to simulate the expected performance when the spacecraft is
at 2.4 AU. These tests indicate that we can expect approximately two hours
of communications per DSN pass before the battery will need to be
recharged. The pre-launch prediction was three hours of
communications. The test assumed the spacecraft is at a 0.95 state of
charge (SOC) when the DSN pass starts and will be at a 0.60 SOC at the
end. Fault protection is activated if the SOC reaches 0.50. The expected
recharge time is approximately 25 hours, matching the pre-launch predict.
For more information on the Stardust mission — the first ever comet sample
return mission — please visit the Stardust home page:
