* Astronomy

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 characterising 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 frequencies 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 characterising dust on the panoramic camera.

Odometry:
As of sol 1298 (Aug. 28, 2007), Spirit's total odometry was 7,169 meters.

Image taken by the Spirit rover on Sol 1295


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Credit: NASA


Image taken by the Spirit rover on Sol 1295


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Credit: NASA

SPIRIT UPDATE: Dust from Martian Sky Accumulates on Solar Panels - sol 1284-1287, August 20, 2007:

Even though the Martian sky above Gusev Crater continued to clear, solar power levels on NASA's Spirit rover remained fairly constant as dust settling from the atmosphere accumulated on top of the solar panels. Activities remained restricted. Measurements of atmospheric opacity, known as Tau, dropped from 3.6 on Martian day, or sol, 1283 (Aug. 12, 2007) to 3.3 on sol 1286 (Aug. 16, 2007), generating power levels of 301 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).
During recent wind storms on Mars, some dust appears to have gotten past the cover of the microscopic imager, based on images Spirit acquired on sols 1279 and 1284-1286 (Aug. 8, 2007 and Aug. 14-16, 2007). Engineers conducting tests with a surrogate rover on Earth hoped to position the instrument in a downward-facing position as early as sol 1290 (Aug. 20, 2007) in an attempt to get accumulated dust to fall out.
While assessing the well-being of the microscopic imager, Spirit completed an analysis of a crushed rock target known as "Innocent Bystander" with the Mössbauer spectrometer and continued to make observations of the ground and atmosphere. The rover remains healthy and is parked just east of the elevated plateau known as "Home Plate."
The forecast for the next week is for no new dust storm activity, based on weather reports provided by Malin Space Science Systems, the builder of the Mars Colour Imager on board the Mars Reconnaissance Orbiter. The camera is being used to monitor conditions on the red planet. Skies are expected to continue to clear over the next couple of months.

Sol-by-sol summary:
Except where noted, daily communications included morning, direct-from-Earth uplinks over the rover's high-gain antenna and evening relays of data to Earth at UHF frequencies via the Odyssey orbiter. In addition, Spirit completed the following activities:

Sol 1284 (Aug. 13, 2007): Spirit placed the Mössbauer spectrometer back on Innocent Bystander and began analysis with the instrument. The rover also acquired images of ripples using the front and rear hazard avoidance cameras and microscopic images looking toward the sky through the dust cover of the microscopic imager. Spirit measured atmospheric opacity with the panoramic camera and surveyed the sky and ground with the miniature thermal emission spectrometer.

Sol 1285: Spirit surveyed atmospheric opacity with the panoramic and navigation camera and acquired images of ripples using the front and rear hazard avoidance cameras. The rover acquired microscopic images looking through the dust cover of the microscopic imager and surveyed the sky and ground with the miniature thermal emission spectrometer.

Sol 1286: Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and measured atmospheric dust with the panoramic and navigation cameras. The rover continued with Mössbauer analysis of Innocent Bystander and took diagnostic images at different times of day looking skyward through the dust cover with the microscopic imager. Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and acquired images with the front and rear hazard avoidance cameras.

Sol 1287 (Aug. 17, 2004): Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and measured atmospheric dust with the panoramic and navigation cameras. The rover continued with Mössbauer analysis of Innocent Bystander and acquired images with the front and rear hazard avoidance cameras. Spirit took more skyward-oriented images through the dust cover with the microscopic imager and surveyed the sky and ground with the miniature thermal emission spectrometer.

Odometry:
As of sol 1287 (Aug. 16, 2007), Spirit's total odometry remained at 7,153 meters.

SPIRIT UPDATE: Gloomy Skies Show Signs of Clearing - sol 1274-1283, August 16, 2007:

Spirit is healthy as the amount of dust hoisted into the atmosphere by recent wind storms has leveled off and solar energy levels have held steady at about 280 to 300 watt-hours of energy (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Since the rover's 1,271st Martian day, or sol, of exploration (July 31, 2007), atmospheric opacity, a measurement known as Tau, has stabilized at about 3.8. Given the apparent relative stability of the atmosphere, the rover's handlers have returned to somewhat more normal planning procedures, allowing the rover to take on more science activities. Spirit studied a crushed rock target known as "Innocent Bystander" using the Mössbauer spectrometer on sols 1275, 1278, and 1281 (Aug. 4, Aug. 7, and Aug. 10, 2007).
Spirit appears to have accumulated some dust contamination on the optics of the microscopic imager at some point during a period of 10 Martian days between sol 1257 (July 17, 2007) and sol 1277 (Aug. 6, 2007). On sol 1282 (Aug. 11, 2007), Spirit got a look at the microscopic imager with the dust cover closed using the panoramic and hazard avoidance cameras. The rover's handlers are considering using the front hazard avoidance cameras to try to get a better look at the microscopic imager with the dust cover open. They are also considering strategies for removing dust if necessary.
Spirit remains parked just to the east of the elevated plateau known as "Home Plate" with the Mössbauer spectrometer placed on Innocent Bystander.

Sol-by-sol summary:
Except where noted, daily communications included morning, direct-from-Earth uplinks over the rover's high-gain antenna and evening relays of data to Earth at UHF frequencies via the Odyssey orbiter. In addition, Spirit completed the following activities:

Sol 1274 (Aug. 3, 2007): Spirit acquired wide-range, panoramic camera images for measuring atmospheric dust, searched for clouds using the navigation camera, acquired movie frames in search of dust devils, and acquired images of surface ripples to the front and rear of the rover with the hazard avoidance cameras. The rover surveyed the external calibration target with the miniature thermal emission spectrometer.

Sol 1275: Spirit conducted studies with the Mössbauer spectrometer, acquired a 3x1 mosaic of images of ripples with the navigation camera, acquired wide-range, panoramic camera images for measuring atmospheric dust, and took images of ripples with the front and rear hazard avoidance cameras. The rover scanned the sky and ground with the miniature thermal emission spectrometer.

Sol 1276: Spirit acquired images of ripples with the front and rear hazard avoidance cameras, acquired wide-range, panoramic camera images for measuring atmospheric dust, acquired a 360-degree panorama of the rover's surrounding with the navigation camera, and searched for clouds with the navigation camera.

Sol 1277: Spirit acquired a stack of microscopic images of targets known as "Stealing Second" and "Stealing Third," a microscopic image of Innocent Bystander, and both wide-range, panoramic camera images and navigation camera images for measuring atmospheric dust. The rover monitored dust on the rover mast, acquired images of ripples with the front and rear hazard avoidance cameras, and surveyed the sky and ground with the miniature thermal emission spectrometer.

Sol 1278: Spirit studied Innocent Bystander using the Mössbauer spectrometer, acquired images of ripples using the navigation camera, and measured atmospheric dust by acquiring wide-range, panoramic camera images as well as navigation camera images. The rover took thumbnail images of the sky and acquired movie frame images in search of dust devils with the navigation camera.

Sol 1279: Spirit acquired images of surface ripples using the rear and front hazard avoidance cameras, acquired a microscopic image looking through the dust cover, and acquired images of the microscopic imager from the outside using the panoramic and navigation cameras. The rover acquired wide-range, panoramic camera images as well as navigation camera images for measuring atmospheric dust, took spot images of the sky, and surveyed the horizon.

Sol 1280: Spirit measured atmospheric properties using the alpha-particle X-ray spectrometer and measured atmospheric opacity with the panoramic and navigation cameras. The rover took images of ripples with the front and rear hazard avoidance cameras, searched for clouds with the navigation camera, and conducted a mini-survey of the sky and ground with the miniature thermal emission spectrometer.

Sol 1281: Spirit acquired wide-range, panoramic camera images and navigation camera images to measure atmospheric dust. The rover conducted studies with the Mössbauer spectrometer, completed a survey at high sun with the panoramic camera, and took images of surface ripples using the navigation and panoramic cameras.

Sol 1282: Spirit extended the robotic arm for panoramic camera images, retracted the robotic arm for hazard avoidance camera images, and extended the rock abrasion tool into ready position. The rover acquired images of ripples using the front and rear hazard avoidance cameras, acquired wide-range, panoramic camera images to measure atmospheric dust, and monitored dust on the rover mast. Spirit conducted a mini-survey of the sky and ground using the miniature thermal emission spectrometer.

Sol 1283 (Aug. 12, 2007): Spirit acquired wide-range, panoramic camera images and navigation camera images for measuring atmospheric dust, took spot images of the sky, surveyed the horizon, acquired a 3x1 mosaic of navigation camera images of surface ripples, and completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer.

Odometry:
As of sol 1283 (Aug. 12, 2007), Spirit's total odometry remained at 7,153 meters.