Team Probes Flash Memory Following Odd Glitch
NASA's Phoenix Mars Mission generated an unusually high volume
of spacecraft housekeeping data earlier this week, causing the loss
of some non-critical science data. Phoenix engineers are now
analyzing why this anomaly occurred; in the meantime, the science
team at JPL plans spacecraft activities for Thursday that will not
rely on Phoenix storing science data overnight but will make use of
multiple communication relays to gain extra data quantity.
"The spacecraft is healthy and fully commandable, but we are
proceeding cautiously until we understand the root cause of this
event," said Phoenix Project Manager Barry Goldstein of NASA's Jet
Propulsion Laboratory.
Usually Phoenix generates a small amount of data daily about
maintaining its computer files, and this data gets a high priority
in what gets stored in the spacecraft's non-volatile flash memory.
On Tuesday, the quantity of this data was so high that it prevented
science data from being stored in flash memory, so the remaining
science data onboard Wednesday, when the spacecraft powered down
for the Martian night after completing its 22nd Martian day, or
sol, since landing, was not retained.
Fortunately, NASA says, none of that science data was
high-priority data. Almost all was imaging that can be retaken,
with the exception of images taken of a surface that Phoenix's arm
dug into after the images were taken.
To avoid stressing Phoenix's capacity for storing data in flash
memory while powered off for overnight sleeps, the team commanded
Phoenix Tuesday evening to refrain from any new science
investigations on Wednesday and to lower the priority for the type
of file-housekeeping data that exceeded expected volume on
Tuesday.
"We can continue doing science that does not rely on
non-volatile memory," Goldstein said. Most science data collected
during the mission has been downlinked to Earth on the same sol it
has been collected, not requiring overnight storage, but on some
sols the team has intentionally included imaging that yields more
data than can fit in the afternoon communication passes. This has
been done in order to take advantage of the capacity to downlink
additional data during communications passes on the following
Martian mornings. In the short term, while the root cause of the
unexpected amount of housekeeping data is being determined, the
science team will forgo that strategy of storing data
overnight.
Meanwhile, extra communication-relay opportunities have been
added to Thursday's schedule, so the science plan for the day will
be able to generate plentiful data without needing overnight
storage. Trench-digging, imaging and weather monitoring are in the
plan.
The Phoenix mission is led by Peter Smith of the University of
Arizona with project management at JPL and development partnership
at Lockheed Martin, located in Denver.
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