Mars Exploration Rovers Update - November 12, 2007

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

SPIRIT UPDATE: Spirit Continues Drive As Power Levels Decline - sol
1363-1369, November 12, 2007:

Spirit has been gradually losing power, with energy levels dropping to
320 watt-hours per Martian day (100 watt-hours is the amount of energy
needed to light a 100-watt bulb for one hour). Measurements of
atmospheric dust, known as Tau, have been averaging 0.65. That dust
level is typical of levels measuring throughout most of the mission, but
power levels are lower than in previous years because of higher dust
accumulation on the solar panels. (The rover estimates dust levels by
measuring opacity – the degree to which the atmosphere is impenetrable
by light. During most of Spirit’s mission on Mars, except during the
recent dust storms, tau values have fallen between 0 and 1.)

During the trek to reach the north edge of “Home Plate” before the next
Martian winter, Spirit had time to conduct only one scientific campaign.
Scientists selected a rock target nicknamed “Pecan Pie” (investigators
are nicknaming targets on top of Home Plate for things served in bowls)
for closer investigation, at a location known as “Site 5.” Spirit
brushed Pecan Pie, took pictures of it with the microscopic imager, and
analyzed its composition with the alpha-particle X-ray spectrometer.
Planned measurements over the weekend included an analysis of
iron-bearing minerals with the Moessbauer spectrometer before resuming
the drive.

The successful brush of Pecan Pie marked the first time that Spirit had
used the new, two-sol brushing procedure that enabled continued use of
the rock abrasion tool following the failure of the grind encoder.

Spirit continued to collect images of the west side of Home Plate (known
as “West Valley” to science team members) while advancing northward. The
images are important for understanding the geology as well as for
planning the hoped-for, post-winter drive to a hill known as “von Braun”
south of Home Plate.

Spirit remains healthy. On Sol 1369 (Nov. 9, 2007), plans called for
Spirit to run a diagnostic of the rock abrasion tool by pointing it at
the hazard avoidance camera for photo documentation while running the
motor at various voltages. The resulting measurements of the spinning of
the tool will provide a baseline for eventual failure of the motor and
for comparison with Spirit’s twin, Opportunity, on the other side of Mars.

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 1363 (Nov. 3, 2007): Spirit acquired pre-drive, panoramic camera
images of targets known as “Posole,” “Green Chile,” and “Flan,” then
drove 24.83 meters (84.46 feet) to Site 5 on Home Plate. The rover
acquired post-drive image mosaics with the navigation and panoramic
cameras. The next morning, Spirit completed a survey of rock clasts with
the panoramic camera and took a mosaic of images with the navigation
camera.

Sol 1364: Spirit acquired images of the distant dune field known as “El
Dorado” with the panoramic camera, and after communicating with the
Odyssey orbiter during its overhead pass, measured atmospheric argon
with the alpha-particle X-ray spectrometer. In the morning, Spirit
completed a full-color, systematic ground survey using all 13 filters of
the panoramic camera.

Sol 1365: Spirit spent the day recharging the battery. The following
morning, Spirit searched for dust devils using the navigation camera.

Sol 1366: Spirit placed the rock abrasion tool on Pecan Pie and acquired
a mosaic of images known as the “West Valley View” with the panoramic
camera. The next morning, the rover took spot images of the sky with the
panoramic camera and acquired movie frames in search of dust devils with
the navigation camera.

Sol 1367: Spirit acquired another mosaic of images of West Valley View
with the panoramic camera. In the morning, Spirit acquired full-color
images, using all 13 filters of the panoramic camera, of the rover’s
tracks.

Sol 1368: Spirit conducted scientific studies of Pecan Pie, including
brushing the surface of the rock target with the brush on the rock
abrasion tool, acquiring stereo microscopic images of the brushed
surface, and collecting 9 hours of compositional data with the
alpha-particle X-ray spectrometer. The rover also acquired a mosaic of
images of West Valley View with the panoramic camera. The following
morning, Spirit took thumbnail images of the sky with the panoramic camera.

Sol 1369 (Nov. 9, 2007): Plans called for Spirit to run diagnostic tests
of the rock abrasion tool and acquire a mosaic of images of West Valley
View with the panoramic camera. The rover was to spend 22 _ hours
acquiring data with the Moessbauer spectrometer, be on the lookout for
morning dust devils, and acquire movie frames at 8-minute intervals to
record the progress of dust devils if they occurred.

Odometry:

As of sol 1367 (Oct. 30, 2007), Spirit’s total odometry was 7,383.75
meters (4.59 miles).


OPPORTUNITY UPDATE: Rock Abrasion Tool Shows Anomalous Behavior - sol
1336-1342, Nov 12, 2007:

During the past week, Opportunity continued to investigate the rock
layer known as “Smith,” the second of three “bathtub-ring” layers of
rock inside “Victoria Crater.” The vehicle is mostly healthy, except for
a recent anomaly involving the rock abrasion tool.

Planned operations with the rock abrasion tool failed on Martian day, or
sol, 1334 (Oct. 25, 2007), during both the calibration and grind-scan
(the procedure for placing the instrument on the target). Data from the
vehicle indicated unusual behavior in the encoder of the revolve motor.

On sols 1336 (Oct. 27, 2007) and 1339 (Oct. 30, 2007), the rover
conducted diagnostic tests of the rock abrasion tool. Data from the
actuator that makes the rock abrasion tool revolve indicated that the
encoder was functioning as expected. However, the encoder for the
actuator that causes the rock abrasion tool to grind has not been
functioning since it failed on sol 1045 (Jan. 1, 2007). Based on the
test results, the team decided to go ahead and retry the grind-scan
procedure on sol 1341 (Nov. 1, 2007).

Sol-by-sol summary:

In addition to standard observations that included measurements of
atmospheric dust with the panoramic and navigation cameras, surveys of
the horizon with the panoramic camera, and transfers of data to Earth
via the Odyssey orbiter, Opportunity completed the following activities:

Sol 1336 (Oct. 27, 2007): Opportunity conducted diagnostic tests of the
rock abrasion tool, placed the Moessbauer spectrometer on Smith, and
acquired full-color images of a rock target known as “Walther” using all
13 filters of the panoramic camera. The rover acquired panoramic camera
images of the band of rock known as “Lyell” and acquired data from Smith
using the Moessbauer spectrometer. The next morning, the rover took a
mosaic of images of the lower part of Lyell.

Sol 1337: Opportunity re-started the Moessbauer spectrometer for
continued analysis of Smith, completed a survey of the sky at high sun
with the panoramic camera, and acquired images of a rock target known as
“Ronov” with the panoramic camera. The next morning, Opportunity
surveyed and took thumbnail images of the sky with the panoramic camera.

Sol 1338: Opportunity conducted diagnostic tests of the rock abrasion
tool and looked for iron-bearing minerals with the Moessbauer
spectrometer. The rover acquired panoramic camera images of targets
called Lyell, “Lyell NorthPart2,” and “Lyell SouthPart2,” as well as
full-color images of a rock target known as “Sorby” with all 13 filters
of the panoramic camera. The following morning, Opportunity surveyed and
took spot images of the sky with the panoramic camera.

Sol 1339: Opportunity ran more diagnostic tests of the rock abrasion
tool and resumed analysis of iron-bearing minerals in Smith with the
Moessbauer spectrometer. Opportunity acquired additional panoramic camera
images of Lyell. After communicating with the Odyssey orbiter during its
overhead pass, Opportunity surveyed the sky at low sun with the
panoramic camera.

Sol 1340: Opportunity re-started the Moessbauer spectrometer for
continued studies of Smith and acquired additional image mosaics of
Lyell using the panoramic camera.

Sol 1341: Plans called for Opportunity to again follow the grind-scan
procedure for placing the rock abrasion tool on the target. The rover
was to acquire full-color images of a rock target known as “Oppel” and
watch the sky for clouds. After communicating with Odyssey, the rover
was to turn the alpha-particle X-ray spectrometer skyward and measure
atmospheric argon and watch for clouds in the sky.

Sol 1342 (Nov. 2, 2007): Plans called for Opportunity to acquire
panoramic camera images of “Cape Verde,” on the rim of Victoria Crater.
Opportunity was then to go into a deep sleep and not conduct any science
activities on the morning of sol 1343 (Nov. 3, 2007).

Odometry:

As of sol 1340 (Oct. 31, 2007), Opportunity’s total odometry was
11,584.32 meters (7.2 miles).