* Astronomy

SPIRIT UPDATE: Rover Slips in Sandy Terrain - sol 1377-1383, November 26, 2007:

On the way to "Winter Haven 3," the spot on the north face of "Home Plate" where NASA's Spirit rover is headed, the rover has driven into an area below a hummock (elevated area). Spirit has tried unsuccessfully during the past week to climb onto the hummock and make progress toward Winter Haven 3. Because it is critical to reach the north face while enough solar energy is available to get there, Spirit spends every available day driving. In-between drives, Spirit recharges the batteries and conducts very light remote sensing.
The rover's drive on sol 1378 (Nov. 18, 2007) ended early when Spirit's unusable, right front wheel got snagged on a buried rock, causing the rover to turn and drive into a "keep-out zone." Two Martian days later, on sol 1380 (Nov. 20, 2007), the drive faulted out again when the rover experienced more than 90-percent slip after travelling 3.6 metres. The rover's handlers continue to work on strategies for enabling Spirit to drive away from the outcrop.
Spirit's top priority is to reach the north-facing slope of "Home Plate," where the rover plans to hunker down during the coming cold, winter season of waning sunlight. Spirit is healthy and all subsystems are nominal. Energy is currently around 305 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

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, and measuring atmospheric dust levels with the panoramic camera, Spirit completed the following activities:

Sol 1377 (Nov. 17, 2007): Spirit acquired an image mosaic of "West Valley" and thumbnail images of the sky with the panoramic camera.

Sol 1378: Spirit drove toward the hummock known as "Site 7," took images just before and after ending the drive with the hazard avoidance cameras, and acquired post-drive image mosaics with the navigation and panoramic cameras. The images indicated that the right front wheel had slipped off a buried rock and turned away from the targeted drive region. The rover acquired full-colour foreground images, using all 13 filters of the panoramic camera.

Sol 1379: Spirit acquired a post-drive, rearward-looking mosaic of images using the navigation camera.

Sol 1380: Spirit drove 3.6 metres, took images before and after the drive with the hazard avoidance cameras, and acquired post-drive image mosaics with the navigation and panoramic cameras. Early the next morning, the rover completed a survey of rock clasts and took images of the rover's tracks (to look for compositional changes revealed by trenching) and the Martian horizon with the panoramic camera.

Sol 1381: Plans called for Spirit to recharge the batteries.

Sol 1382: Plans called for Spirit to monitor dust on the miniature thermal emission spectrometer, acquire panoramic camera images of a target known as "Sorbet" near the centre of Home Plate, and acquire movie frames in search of dust devils using the navigation camera.

Sol 1383 (Nov. 24, 2007): Plans called for Spirit to calibrate the panoramic camera by taking images in darkness, acquire spot images of the sky with the panoramic camera, check for drift (changes over time) in the miniature thermal emission spectrometer, and survey the sky and ground with the miniature thermal emission spectrometer.

Odometry:
As of sol 1380 (Nov. 20, 2007), Spirit's total odometry was 7,428.01 metres.

The High Resolution Imaging Science Experiment, or HiRISE, camera onboard the Mars Reconnaissance Orbiter has taken a new colour image of the feature dubbed "Home Plate" in Gusev Crater on Mars.


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Credit: NASA/JPL/University of Arizona

The Mars rover "Spirit" is indicated by a circle on "Home Plate" in this part of new HiRISE image of Gusev Crater on Mars. This detail is part of a much larger image that the HiRISE camera took on Sept. 27, 2007. The rover has since been driving north, toward the top of the image.

Image taken by the Spirit rover on Sol 1377.


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Credit: NASA/JPL/University of Arizona

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 measured 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 analysed its composition with the alpha-particle X-ray spectrometer. Planned measurements over the weekend included an analysis of iron-bearing minerals with the Mössbauer 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 metres  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-colour, 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-colour 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 Mössbauer 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.