Mars Exploration Rovers Update - December 17, 2007

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

SPIRIT UPDATE: Final Winter Haven Selection Near - sol 1398-1403, December 17, 2007:

To make the most of waning sunlight during the approach of Martian winter, Spirit’s handlers have returned to “Mars time.” This means their working hours coincide with the Martian day, as they did for the first three months after the rover landed on the red planet. Because a Martian day is about 40 minutes longer than an Earth day, Mars time can coincide with all hours of the day and night on Earth. The alarm might go off the same time one day, 40 minutes later the next day, an hour and 20 minutes later the next day, and so on.

Spirit’s solar power levels continue to drop, with solar array energies recently ranging from 293 watt-hours to 254 watt-hours, depending on the vehicle’s orientation relative to the Sun. (One hundred watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.)

All members of the rover science team – drivers, engineers, and scientists – are evaluating data to select a place where the rover will attempt to survive another Martian winter, focusing on areas that will tilt the rover’s solar panels to the north more than 25 degrees. They will select a final location from a narrowed list of choices based on proximity to the rover’s current position and the characteristics of the terrain, with an eye for accessibility as well as continued exploration in the spring.

Spirit reached the northern edge of “Home Plate” after driving 13.24 meters (43.44 feet) on Martian day, or sol, 1397 (Dec. 8, 2007). Three Martian days later, on sol 1400 (Dec. 11, 2007), Spirit finished collecting reconnaissance images of the northern exposure of the elevated plateau.

During the past week, rover planners got a special visit from two Tuskegee Airmen, the first black pilots to serve in the U.S. military. The pilots shared stories about serving in World War II while learning about rover operations.

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 1398 (Dec. 9, 2007): Spirit drove 6.5 meters (21.3 feet) in a path nearly parallel to the northern edge of Home Plate. The rover acquired post-drive images with the hazard avoidance cameras and a mosaic of images with the navigation camera.

Sol 1399: Spirit drove 7.19 meters (23.6 feet) toward a small promontory to acquire images of the slopes below. The rover acquired post-drive images with the hazard avoidance cameras and a mosaic of images with the navigation camera. The following morning, Spirit acquired a series of navigation camera images to complete a 360-degree view of the rover’s location after completing the drive.

Sol 1400: Spirit nudged 0.75 meter (2.5 feet) closer to the edge of Home Plate for a better view of what lay below. The rover acquired post- drive images with the hazard avoidance cameras and a mosaic of images with the navigation camera.

Sol 1401: Spirit took a break from driving and acquired images with the panoramic camera before turning around to back down the steep slope where the rover will spend the winter. After turning, the rover’s solar arrays blocked the view of the slope by cameras on the rover mast assembly. Following the maneuver, Spirit acquired two image mosaics with the panoramic camera.

Sol 1402: Spirit acquired a pre-drive image of a pointy rock known as “General B.O. Davis” before backing up 2.5 meters (8.2 feet) and turning 180 degrees. The rover acquired post-drive images using the hazard avoidance cameras and a mosaic of images using the navigation camera. The following morning, Spirit monitored dust on the panoramic camera mast assembly and completed a systematic ground survey and a survey of rock clasts with the panoramic camera.

Sol 1403 (Dec. 14, 2007): Plans called for Spirit to approach the edge of Home Plate backward and acquire post-drive images with the hazard avoidance cameras as well as an image mosaic with the panoramic camera.

Odometry:

As of sol 1402 (Dec. 13, 2007), Spirit’s total odometry was 7523.31 meters (4.67 miles).


OPPORTUNITY UPDATE: Opportunity Maneuvers Around Steeper Slopes in “Victoria Crater” - sol 1375-1381, Dec 17, 2007:

Opportunity is now in the process of driving to the third band of light-colored rocks that circumvent “Victoria Crater” beneath the rim. Scientists had initially planned to have the rover head directly downhill to a rock target nicknamed “Ronov,” within the band known as “Lyell.” They selected an alternate rock exposure, dubbed “Newell,” when engineers determined that the original drive route would tilt the rover 25 degrees, somewhat higher than desired. The estimated tilt along the new route is a much gentler 20 degrees but the drive is somewhat more complex and required two days of planning.

During the past week, Opportunity completed scientific investigation of the second band of rocks, known as “Smith,” with an analysis of elemental chemistry and iron-bearing minerals beneath the surface of a rock exposure labeled “Smith2.” To do this, the rover collected data with the alpha-particle X-ray spectrometer Moessbauer spectrometer, respectively.

If next week’s planned drive goes as anticipated and closer inspection of Newell deems it to be an acceptable target, Opportunity is likely to stay at the new location for several weeks collecting data. Scientists plan to have the rover conduct a complete campaign of studies with the alpha-particle X-ray and Moessbauer spectrometers, microscopic imager, rock abrasion tool, and on-board cameras.

During the planned drive, Opportunity will complete a “Get Quick Fine Attitude,” a procedure for determining the rover’s position relative to the changing position of the Sun. This activity recalibrates the inertial measurement unit and eliminates tiny errors that accumulate over time in pointing the antenna.

Opportunity is healthy and all subsystems are operating as expected. The latest available power readings, taken on Martian day, or sol, 1379 (Dec. 10, 2007), show solar energy levels at a robust 601 watt-hours, enough to light a 100-watt bulb for 6 hours.

Sol-by-sol summary:

In addition to morning uplinks directly from Earth via the rover’s high-gain antenna, evening downlinks to Earth via the Odyssey orbiter at UHF frequencies, and standard measurements of atmospheric opacity caused by dust using the panoramic camera, Opportunity completed the following activities:

Sol 1375 (Dec. 6, 2007): Opportunity placed the alpha-particle X-ray spectrometer on Smith2 and, after the overpass of the Odyssey orbiter, collected data with the instrument. The next morning, when the Sun powered the solar arrays, Opportunity scanned the sky for clouds with the navigation camera.

Sol 1376: Opportunity conducted extensive measurements of atmospheric dust and scanned the sky for clouds with the navigation camera.

Sol 1377: Opportunity placed the Moessbauer spectrometer on Smith 2 and collected data with the instrument. Opportunity acquired calibration images and part 1 of a panoramic view of the rover deck that involved 23 pointings with the panoramic camera. The rover surveyed the sky at high sun with the panoramic camera and scanned the sky for clouds with the navigation camera.

Sol 1378: Opportunity re-started the Moessbauer spectrometer and continued data collection from Smith2. The rover acquired part 2 of a panoramic view of the rover deck, completing 24 pointings of the panoramic camera. Opportunity surveyed and took spot images of the sky for calibration purposes using the panoramic camera.

Sol 1379: Opportunity re-started the Moessbauer spectrometer and resumed data collection from Smith2. The rover then acquired part 3 of the panoramic view of the spacecraft deck, a series that entailed 29 pointings of the panoramic camera. In the morning, Opportunity scanned the sky for clouds with the navigation camera and monitored dust on the rover mast assembly.

Sol 1380: Opportunity scanned the sky for clouds with the navigation camera.

Sol 1381 (Dec. 12, 2007): Opportunity surveyed the sky at low sun with the panoramic camera and measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer. The rover searched for clouds in the morning sky with the navigation camera.

Odometry:

As of sol 1379 (Dec. 5, 2007), Opportunity’s total odometry remained at 11,584.32 meters (7.2 miles), where the rover has been stationed since the last drive on Sol 1329 (Oct. 20, 2007).

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