[meteorite-list] Mars Exploration Rover Update - August 30, 2007

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 31 Aug 2007 08:45:11 -0700 (PDT)
Message-ID: <200708311545.IAA07115_at_zagami.jpl.nasa.gov>

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

SPIRIT UPDATE: Spirit Slowly Emerges from Blanket of Dust -
sol 1295-1302, August 30, 2007:

Spirit remains healthy as the rover slowly picks up more solar energy.
The dust storms appear to be over, at least for now, and the skies are
slowly clearing. Unfortunately, what energy Spirit has gained from
cleaner skies has been offset by losses to dustier solar arrays. Still,
Spirit has the energy, about 325 watt-hours, to finally be roving again.

Tau, a measure of atmospheric dustiness, declined slightly. As of Sol
1299 (Aug. 29, 2007), the Sun was at about 8 percent of its full
brightness, an increase of a little more than 2 percent compared with
five sols earlier. Dust on the rover's solar arrays increased by about 3
percent and only about 59 percent of the sunlight hitting the arrays
gets through to make electricity.

But rather than getting a 1-percent boost in solar power, the rover has
been just about breaking even. The reason is that Tau measures direct
sunlight but there's also scattered sunlight and it, too, increased by
about 1 percent.

Much of the dust previously seen on the turret has blown or fallen off.
Dust contamination remains a concern, particularly for the microscopic
imager, where some of the dust clumps visible in earlier images have
fallen out or moved out of the line of sight.

On Sol 1296 (Aug. 25, 2007), Spirit resumed driving to "Home Plate" and
more specifically, to a location with gentle slopes and few rocks known
as "the on-ramp." This drive was a turn-in-place, given Spirit's frozen
right front wheel, to get the rover pointed in the right direction.

After two sols of remote sensing with emphasis on characterizing
whatever dust had accumulated on the panoramic camera, Spirit's handlers
decided to have the rover retrace its tracks to assess what dust
contamination might be present on the miniature thermal emission
spectrometer. To do this, they needed to measure a known target.

With a blanket of dust everywhere, scientists needed a way to
distinguish dust on targets of scientific interest from dust on the
optics. The best target for that was "Gertrude Weise," a patch of nearly
pure-silica soil uncovered by Spirit's wheels. Rover planners decided to
have the rover drag its wheels through it again to scrape off newly
acquired dust and expose the same pure silica as before. Differences
between old and new measurements would be due to dust on the instrument
itself; once that signature was known, it could be subtracted from
future measurements.

The first drive to Gertrude Weise was a little short and didn't uncover
the silica as hoped. Spirit's handlers planned a second drive on Sol
1300 (Aug. 30, 2007), during which the rover was to scuff the soil with
a half-turn of the left front wheel, then scuff it more by locking both
left and right front wheels and driving them backward across Gertrude
Weise. They then planned to have the rover back up some more to take
images and move toward the Home Plate on-ramp.

Spirit was expected to resume the long-awaited trek to Home Plate on sol
1303 (Sept. 2, 2007).

Sol-by-sol summary:

In addition to daily direct-from-Earth uplinks over the rover's
high-gain antenna, relays to Earth at UHF frequences via the Odyssey
orbiter, surveys of the sky and ground with the miniature thermal
emission spectrometer, measurements of atmospheric opacity with the
panoramic and navigation cameras, and image acquisition with the front
and rear hazard avoidance cameras, Spirit completed the following
activities:

Sol 1295 (Aug. 25, 2007): Spirit conducted remote sensing and acquired
panoramic camera images of targets known as "Eileen Dean," "Dorothy
Mueller," and "Stealing Third."

Sol 1296: Spirit drove and turned in place 156 degrees to point toward
the on-ramp of Home Plate. The rover assessed dust accumulation on the
lenses of the panoramic camera and measured atmospheric opacity (Tau) at
different times of day.

Sol 1297: Spirit conducted remote sensing and general atmospheric
science, including characterizing dust on the panoramic camera.

Sol 1298: Spirit drove, returning to Gertrude Weise.

Sol 1299: Spirit conducted remote sensing and general atmospheric
science, including characterizing dust on the panoramic camera.

Sol 1300: Plans called for Spirit to drive, scuff and drag its wheels
over Gertrude Weise, and acquire images of the target. The rover was to
conduct atmospheric science.

Sol 1301: Plans called for Spirit to conduct remote sensing and general
atmospheric science, including characterizing dust on the panoramic
camera. The rover was to measure atmospheric argon with the
alpha-particle X-ray spectrometer.

Sol 1302 (Sept. 1, 2007): Plans called for Spirit to conduct remote
sensing and general atmospheric science, including characterizing dust
on the panoramic camera.

Odometry:

As of sol 1298 (Aug. 28, 2007), Spirit's total odometry was 7,169 meters
(4.45 miles).
Received on Fri 31 Aug 2007 11:45:11 AM PDT