Stardust Status Report 5 Jan 2001
During the holiday period there were numerous Deep Space Network
(DSN) tracking passes. All subsystems onboard the spacecraft are
performing normally.
The STARDUST spacecraft is within 4,000,000 km from the Earth and
closing rapidly. The spacecraft will make its closest approach to
Earth on January 15, at 11:15 Universal time. There is a small
possibility that STARDUST may be visible from Earth after flyby
using sophisticated telescopes with CCD detectors. Additional
information will be available on the STARDUST website.
In preparation for the Earth Gravity Assist, the Command
Loss Timer was changed to three days from its usual value of nine days.
The CLT is an onboard countdown clock based on the last successful
command received by the spacecraft. When the CLT reaches zero or when
there is no communication from Earth for nine days — the safe mode
executive assumes there is a problem somewhere in the spacecraft’s
uplink path and requests safe mode. The SME will then autonomously
swap components in the uplink path, pausing in between swaps, until a
command is received. Since STARDUST is rapidly approaching EGA, the
command loss time was reduced to three days to allow a faster recovery
in the unlikely failure of an uplink component. This strategy will
allow the spacecraft team to respond to a failure and ensure that
critical commands are successfully sent to the spacecraft in a timely
manner.
Also, a timer in the SME was changed to ensure that if a safe mode
entry occurs, the spacecraft will remain pointed at the Sun and not
attempt to communicate with the Earth. If the spacecraft enters safe
mode just prior to the closest approach, the batteries would reach
their low state of charge limit (50%) because the Earth and Sun are 180
degrees apart. If the spacecraft enters safe mode after closest
approach, the SME will command the spacecraft to a power-friendly
communications attitude. This change will ensure the spacecraft
remains in a safe attitude, pointed at the Sun, until the spacecraft
team commands it to “phone home”.
This morning, STARDUST successfully completed Trajectory Correction
Maneuver #5 (TCM-5), the final targeting for Earth flyby in 10 days.
Five Navigation Camera images were taken to assess camera performance
after the 2nd heating sequence where both the CCD and
mirror motor heaters were turned on for about 1 month. These images
will be played back later today. The spacecraft will then be left
alone until after Earth flyby.
On January 12, a live interview with Stardust project manager Tom
Duxbury will be shown on NASA TV, followed by an animation of the
Earth flyby and pictures of the spacecraft. To see the interview,
tune to satellite GE-2, Transponder 9C at 85 degrees West longitude,
with vertical polarization. Frequency is on 3880.0 megahertz with
audio on 6.8 megahertz.
For more information on the STARDUST mission – the first ever comet
sample return mission – please visit the STARDUST home page:
