Stardust mission update: 38 days to Tempel 1
Posted by Emily Lakdawalla
07-01-2011 10:25 CST
The Stardust mission posts regular status updates to its website but they're a bit buried, so I'm glad for the watchful members of unmannedspaceflight.com who point them out as soon as they're posted. The latest update, dated yesterday, says that the spacecraft is healthy after performing a "cold boot" to clear a memory address problem (a "memory address latch-up") that occurred late last year and caused the spacecraft to go into safe mode three times. "This cold boot clears the latched line and resets the memory to its factory settings. The activity, performed on January 4 went exactly as expected, and the spacecraft is now back in its comet approach configuration, ready to take the next set of Optical Navigation images on January 6."
However, there are some new challenges facing Stardust: they have downgraded their estimate of how much maneuvering fuel remains onboard the spacecraft, and they could not find Tempel 1 in their first two sets of optical navigation images collected in December. "Current estimates show that the comet may not be bright enough to detect with the Navcam until the latter half of January. Since optical navigation is key to the approach targeting, the trajectory correction maneuver plan has changed to accommodate this information."
So here is a timeline for the approach phase of the mission based on the rest of the status update.
|January 6||Daily Optical Navigation imaging begins|
|January 31||Trajectory Correction Maneuver (TCM) 31|
|February 7||TCM 32|
|February 7||Approach science imaging begins|
The update says: "This new plan accommodates positive fuel margin through encounter, preserves fuel reserves to accommodate larger than expected deviations in the comet ephemeris estimates, and places the TCMs at times best able to accommodate late detection of the comet. The spacecraft team is completing the tests of the approach and flyby sequences, and is building the approach sequences that will control the spacecraft over the next several weeks."