Mars Exploration Rovers Update - December 14, 2004

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

SPIRIT UPDATE: Trekking Toward 'Husband Hill' - sol 326-332,
December 14, 2004

Spirit drove five of the last seven days, continuing its trek towards
the top of "Husband Hill." Spirit's intermediate goal is a ridge dubbed
"Larry's Lookout," which is roughly 75 meters (246 feet) away. Getting
there using Spirit's current path will be a challenge given the sand,
slope, and rocks in this area. Spirit paused for a set of weekend
observations of a rock called "Wishstone." Total odometry for the
mission is now 3,944 meters (2.45 miles).

The amount of electric current drawn by the motor on the right front
wheel is in the normal range. Near the end of Spirit's long series of
drives from "Bonneville Crater" to the "Columbia Hills," the right
front
wheel began to draw roughly twice the current of the other five wheels.
The increased current prompted engineers to limit the use of this wheel
to preserve its life. Since arriving at the hills, Spirit has had
relatively few driving days. The rover team's current working theory on
this problem suggests that the recent rest periods have allowed the
lubricant in this wheel to redistribute, causing the current draw to
return to normal. Periodic rest days will be included in rover drivers'
plans, and Spirit will alternate forward and backward driving to keep
the lubricant in all of the wheels more evenly distributed.

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OPPORTUNITY UPDATE: Out of 'Endurance' - sol 306-315,
December 14, 2004

Opportunity has finished its work inside "Endurance Crater" and climbed
out. Before leaving, the rover examined a transition point between dark
and light rock layers about 20 meters (about 66 feet) from the rim of
the crater. Communication with Mars Odyssey has been good, so the
backlog of onboard data has improved. The rover spent six months inside
the stadium-sized crater to study layered bedrock exposed there. The
exit drive on sol 315 put Opportunity completely outside the crater for
the first time since sol 134. Opportunity continues to be in excellent
health.

Sol details:

Sol 306 was the second sol of inspecting a rock target called "Paikea"
with tools on the robotic arm. On the previous sol, Opportunity had
cleaned the surface of Paikea with its rock abrasion tool brush. During
sol 306, the rover observed the target with the panoramic camera and
the
microscopic imager, then ground away a patch of the rock's surface for
about two hours with the rock abrasion tool. After the grind, the rover
examined the fresh hole in the rock with the panoramic camera,
hazard-avoidance camera and microscopic imager. This was followed by
placement of the alpha particle X-ray spectrometer on the abraded area
for later data collection. The rover woke at about 4:45 a.m. (local
solar time) for a morning communication-relay pass with Odyssey on sol
307. Then it turned on the alpha particle X-ray spectrometer and
gathered data until mid-morning.

Sols 307 through 309 were planned together as a three-sol plan. Sol 307
was similar to sol 306, with imaging, rock grinding, and overnight
X-X-ray
spectrometer measurements, this time targeted on "Wharenhui." Also,
between 1:30 p.m. and 2 p.m. local solar time, Opportunity used its
miniature thermal emission spectrometer and panoramic camera to make
observations coordinated with a Mars Global Surveyor overflight. In the
late morning of sol 308, the rover placed its Mossbauer spectrometer on
the freshly drilled hole in Wharenhui, and then collected data nearly
continuously for the next two sols. In order to provide sufficient
energy for this extended integration, overnight communication passes
for
the early mornings of sols 309 and 310 were sacrificed.

The grinding activity on sol 307 was not as productive as hoped, so
plans for the next couple of sols were revised. Because the team had to
wait for retransmission of some rock abrasion tool data on sol 310, the
sol was spent using the microscopic imager, placing the alpha particle
X-X-ray spectrometer, and performing about an hour of remote-sensing
observations.

Sol 311 was spent re-grinding Wharenhui. The plan was to grind another
3
to 4 millimeters (0.1 to 0.2 inches) into the rock. The grind went as
planned, microscopic images were taken and the alpha particle X-ray
spectrometer was placed in the hole. That spectrometer's integration
was
not started until the sol 312 early-morning Odyssey pass at 4:20 a.m.
Mars local time.

The plan for sol 312 was to complete the alpha particle X-ray
spectrometer integration begun in the early morning, perform about 45
minutes of observations with the panoramic camera and navigation
camera,
then drive about 12 meters (39 feet) toward the crater rim.
Total odometry after sol 311 was 1,766.07 meters (1.1 miles).