STARDUST Status Report
July 30, 1999
The STARDUST spacecraft is healthy with spacecraft operations and
telecommunications normal. A new command sequence was completed and
successfully radioed to the spacecraft last night. In a communications
session with the spacecraft on Saturday, July 24, it was determined that
the spacecraft had placed itself in a safe mode the week before and was
awaiting new commands from controllers on Earth. The spacecraft was taken
out of safe mode during a subsequent communications session on Monday
night (July 26) and Tuesday afternoon (July 27). STARDUST had
placed itself in a safe mode on July 18 at 03:50 UTC (Saturday at
9:50 PM MDT), and had been turning its antenna to Earth for
telecommunications for three hours every 24 hours to receive new commands.
The spacecraft's timing of each three-hour attempt to communicate with Earth,
however, was based upon the time at which the spacecraft had entered safing.
Thus, the spacecraft missed its scheduled communications session on
Thursday, July 22, and the Deep Space Network was not listening for
STARDUST during the short period of time the spacecraft was making itself
available for telecommunications. The communications mismatch was solved
when additional Deep Space Network tracking time, donated by other
missions, allowed the STARDUST team to keep the telecommunications line
open until STARDUST checked in again on Saturday night (July 24). The
communications hiatus was related to the spacecraft's current distance
from the Sun and the need to leave its solar panels pointed at the Sun most
of the time to keep its electrical power supply constant; the resulting
geometry requires STARDUST to turn its telecommunications antenna away
from Earth except during short communications sessions with controllers.
Apparently, the event that triggered the safing event was an error in the
Payload Attitude Control Interface (PACI) card in the Command and Data
Handling (CDH) subsystem which is still under investigation.
The STARDUST Project Principal Investigator, Professor Don Brownlee,
participated in the International Asteroids, Comets, and Meteors Conference
at Cornell University this week.
For more information on the STARDUST mission - the first ever comet sample
return mission - please visit the STARDUST home page: