Mars Exploration Rover Update - July 2, 2004

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

SPIRIT UPDATE: Moving On From 'Pot-of-Gold' - sol 171-174,
July 02, 2004

On sol 171, Spirit continued its investigation in "Hank's
Hollow" and the rock target "Pot-of-Gold." The rover
successfully completed observations of the abraded area
with the microscopic imager and alpha particle X-ray
spectrometer.

On sol 172, Spirit looked at the sky with the miniature
thermal emission spectrometer and panoramic camera. The
rover also acquired some thermal inertia observations of
nearby soil with the miniature thermal emission
spectrometer. Spirit finished up its Pot-of-Gold
observations with some microscopic images and a final
long Mossbauer integration of the abraded surface.

On sol 173, Spirit performed atmospheric observations
with the miniature thermal emission spectrometer and
panoramic camera. The rover also took some panoramic
camera context images for the sol 172 thermal inertia
observations. The rover finished the day's work by
stowing the instrument deployment device and doing a
"bump-back" to the "Bread Box" target. One last
panoramic camera shot of Pot-of-Gold ended up a bit
overexposed and will need to be retaken.

On sol 174, Spirit began the day acquiring atmospheric
observations with the mini thermal emission spectrometer
and panoramic camera. The rover then imaged the drive
direction with the panoramic camera. Last but not least,
Spirit took a look at a disturbed area of soil called
"Bright Tracks" with the panoramic camera to help
scientists learn more about the very bright material
found here.

During the next 15 or more sols, rover planners will
perform a "3,000 meter tune-up" on Spirit before the
rover embarks on a climb up the hills.

The tune-up will include a number of elements including:

A front hazard avoidance camera calibration where a
series of robotic arm poses and hazard avoidance camera
images will be used to refine the rover planners'
ability to target objects using stereo hazard avoidance
camera images. The team is currently experiencing a 2 to
3 centimeter (slightly less or slightly greater than an
inch) error in predicted versus actual target locations
in the vicinity of the instrument deployment device.

Spirit's first deep sleep. Deep sleep is a mode that
leaves the rover completely un-powered overnight,
saving the energy that would be spent powering rover
electronics and survival heaters that are normally on
even when the rover is napping. Spirit needs deep
sleep to save energy in the coming sols. Since deep
sleep is potentially harmful to the mini thermal
emission spectrometer instrument because its survival
heater is not powered, rover planners have identified
two observations that must be completed before the
first deep sleep is attempted. Opportunity has been
using deep sleep for several weeks now.

A right front wheel lubrication. Spirit's right front
wheel continues to draw roughly twice the current of
the other wheels. Spirit will drive to "Engineering
Flats," a relatively flat, hazard-free area where
rover planners will execute a series of diagnostic
drive tests and heating sequences over the course of
four to five sols. The intent is that the heating
will re-flow the lubricants in this actuator,
correcting the problem. Engineering Flats is roughly
7 meters (nearly 23 feet) from Spirit's current
location.

Engineering tests of visual odometry. Visual odometry
uses navigation camera images taken during a drive to
determine the rover's location. This rover feature
has been improved and is ready for trial runs now.
Rover planners would like to use it on a regular
basis to get Spirit where they want it to go more
quickly. Due to slippage, Spirit sometimes needs
two or more sols to make a short approach when
using the blind drive technique.