Mars Exploration Rover Update - April 12, 2004

http://marsrovers.jpl.nasa.gov/mission/status.html

OPPORTUNITY UPDATE: Opportunity Stands Down for Flight Software
Update - sol 78, Apr 12, 2004

Opportunity began a four-sol stand-down on sol 75, which ended
at 8:58 a.m. PST on April 9, 2004. During this time, the rover
will receive a flight software update that should make its
remaining martian days even safer and more productive. The
upload will run through sol 78 with a rover re-boot on sol 79,
Tuesday, April 13.

Opportunity is currently parked near the trench it dug on its
73rd martain sol. It will remain there for the duration of the
flight software update. To keep the battery charge high,
engineers are not planning to integrate the rover spectrometers
on a target in the trailings of the trench during the flight
software update.

The flight software update package includes three key changes.
First is an update to the autonomous navigation software that
will allow both rovers to travel longer distances autonomously.
The current autonomous navigation software sometimes gets stuck
when it detects a hazard that it can't navigate around. The new
version will allow the rovers to turn in place to find the best
possible path.

The second part of the flight software update will allow the
rovers to recover more easily from an anomaly like the one that
occurred on Spirit's sol 18. Although operational processes and
software have already been updated to prevent something like this
from ever happening again, engineers have included additional
safety nets in the software that would allow the rovers to
autonomously react to a similar anomaly and recover to a more
stable state.

The third portion of the update is specific to Opportunity and is
intended to mitigate against energy loss associated with the stuck
heater on Opportunity's instrument deployment device. The fix
allows rover planners to put the rover in a deep sleep mode, where
the batteries are totally removed from being able to power the
stuck switch. Therefore, with no power reaching the stuck heater
switch, the Opportunity rover battery will not be drained. Rover
controllers will not initiate the deep sleep capability on Spirit
unless it becomes necessary.