Mars Exploration Rover Update - November 2, 2007

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

SPIRIT UPDATE: Spirit to Head North for the Winter - sol 1355-1362,
November 02, 2007:

With Martian winter approaching, the science and engineering teams have
been hard pressed to select a site where Spirit can spend the winter.
After previously narrowing the list of candidates to two sites, Spirit’s
handlers decided to send the rover to the northern edge of the elevated
plateau known as “Home Plate,” which Spirit has been exploring for many
months now.

Previously considered sites included “von Braun,” “South Promontory,”
“Batter’s Box” (“West Knoll”), and “North Home Plate.” The decision
means the rover will move farther away from tantalizing, new terrain to
the south, but maximizes the rover’s chances of surviving another winter
given the excessive coating of dust on the solar arrays.

As Project Manager John Callas announced in an e-mail, “the principal
discriminator was the achievable slope at each site. The north side of
‘Home Plate’ offers slopes of 25 degrees of northerly tilt, while ‘South
Promontory’ offers 20 degrees of northerly tilt. That difference is
about 10 watt-hours per sol, which can mean the difference between
surviving and not surviving the cold, dark winter.”

Meanwhile, Spirit remains healthy and all subsystems are nominal. Energy
has been averaging 355 watt-hours (100 watt-hours is the amount of
electricity needed to light one 100-watt bulb for one hour) and
atmospheric dust measurements (Tau) have been steady at about 0.63.

Plans called for Spirit to head in a northerly direction, toward an area
known as “Site 5” on top of Home Plate, starting on sol 1362 (Nov. 2,
2007). Once there, Spirit may investigate some targets with instruments
on the robotic arm before continuing to the north end of Home Plate.

Meanwhile, engineers working on the rover’s miniature thermal emission
spectrometer have determined that degradation in performance of the
spectrometer on both Spirit and its twin, Opportunity, is the result of
dust deposition on the scan mirror or in the panoramic camera mast
assembly. They have decided not to use the instrument on Opportunity and
to use it only for high-priority targets and weekly atmospheric
measurements on Spirit while they try to develop strategies for removing
the dust.

In addition, tests run on sols 1355, 1358, and 1360 (Oct. 25, Oct. 29,
and Oct. 31) determined that the grind motor on Spirit’s rock abrasion
tool failed on sol 1341 (Oct. 11, 2007) , as it did previously on
Opportunity on sol 1045 (Jan. 1, 2007). However, because the rover’s
handlers have devised an alternate technique for grinding and brushing
that takes two Martian days, they are still able to use the brushes on
both rock abrasion tools.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via
the high-gain antenna, sending evening data to Earth at UHF frequencies
via the Odyssey orbiter, measuring atmospheric dust levels with the
panoramic camera, and surveying the sky and ground with the miniature
thermal emission spectrometer, Spirit completed the following activities:

Sol 1355 (Oct. 25, 2007): Spirit unstowed the robotic arm, conducted
imaging diagnostics of the rock abrasion tool, and took microscopic
images of the capture magnet. The rover placed the alpha-particle X-ray
spectrometer on the capture magnet, took panoramic camera images of the
rover deck, and transmitted data overnight via the Odyssey orbiter.
Spirit monitored dust on the panoramic camera mast assembly, surveyed
the horizon with the panoramic camera, acquired a mosaic of images with
the navigation camera, and acquired movie frames in search of dust
devils with the navigation camera.

Sol 1356: Spirit acquired panoramic camera images of the rover deck and
of rock targets nicknamed “Grays Peak,” “Elk,” and “San Juan.” The rover
acquired 6 hours worth of data with the alpha-particle X-ray
spectrometer and took thumbnail images of the sky with the panoramic
camera.

Sol 1357: Spirit used the navigation camera to survey the surface
darkened by the rover’s shadow. The rover acquired full-color images of
its tracks using all 13 filters of the panoramic camera. Spirit acquired
another 6 hours of data with the alpha-particle X-ray spectrometer and
took spot images of the sky with the panoramic camera.

Sol 1358: Spirit took images of the filter magnet with the microscopic
imager, performed diagnostic tests on the rock abrasion tool, and used
the panoramic camera to take images of the rover deck and survey the
horizon.

Sol 1359: Spirit turned in place for communications relays and performed
a “get quick fine attitude” to check for changes in the inertial
measurement unit to determine the rover’s precise location. Spirit
acquired post-drive images with both the navigation and panoramic
cameras. In the morning, the rover completed a systematic ground survey
with the panoramic camera.

Sol 1360: Spirit unstowed the robotic arm, performed diagnostic tests of
the rock abrasion tool, and acquired a mosaic of microscopic images of a
soil target known as “Pumpkin Pie” before placing the alpha-particle
X-ray spectrometer on the target. Spirit acquired full-color images,
using all 13 filters of the panoramic camera, of another soil target
known as “Candy Corn.” The rover collected data from Pumpkin Pie with
the alpha-particle X-ray spectrometer and in the morning, scanned the
sky for clouds with the navigation camera. Spirit also surveyed the
horizon with the panoramic camera and acquired movie frames in search of
dust devils with the navigation camera.

Sol 1361: Spirit stowed the robotic arm in preparation for the next
day’s drive and took full-color images, using all 13 filters of the
panoramic camera, of Elk and San Juan. The rover acquired a mosaic of
images with the navigation camera as part of a 360-degree panorama for
drive planning. Spirit surveyed the sky at both low sun and high sun
with the panoramic camera.

Sol 1362 (Nov. 2, 2007): Plans called for Spirit to drive toward Site 5,
acquire full-color, mid-drive images of Pumpkin Pie with all 13 filters
of the panoramic camera, and acquire post-drive images with both the
navigation and panoramic cameras. The following morning, Spirit was to
complete a survey of rock clasts with the panoramic camera and scan the
sky for clouds with the navigation camera.

Odometry:

As of sol 1359 (Oct. 30, 2007), Spirit’s total odometry was 7,339.70
meters (4.56 miles).