Mars Exploration Rovers Update - April 3-16, 2008

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

SPIRIT UPDATE: Spirit Still “Sitting Pretty” for This Time of Year - sol 1517-1524, April 09-16, 2008:

Despite a slight increase in atmospheric opacity caused by dust, Spirit is still enjoying higher-than-expected energy levels for this time of year. Solar array input has been approximately 240 watt-hours per Martian day, or sol (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

Clear skies have had the unfavorable effect, however, of causing a drop in temperatures at the surface of Mars, increasing the bitter cold experienced by Spirit’s rover electronics module. Nighttime temperatures are creeping closer to the point where they will trigger the survival heaters, which draw a large amount of power. A much more desirable strategy is to keep Spirit awake long enough each day to keep the electronics module sufficiently warm with heat from normal operations, providing more time for science observations. “Awake time” vs. heating time is just one of the many trade-offs the team makes each day to keep Spirit going through the Martian winter.

Sol-by-sol summary:

In addition to daily communications that include direct-from-Earth instructions via the rover’s high-gain antenna and, as power permits, data relays to Earth via the Odyssey orbiter, Spirit continues to monitor atmospheric dust levels each day with the panoramic camera. In addition, during the past week, Spirit completed the following activities:

Sol 1517 (April 9, 2008): Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; acquired column 8, part 3 of the full-color “Bonestell Panorama” using all 13 filters of the panoramic camera; and shot movie frames in search of clouds with the navigation camera.

Sol 1518: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; acquired a 2-by-1-by-1 stack of microscopic images of the rover’s solar array; acquired column 9, part 1 of the Bonestell panorama; and took spot images of the sky for calibration purposes with the panoramic camera.

Sol 1519: Spirit surveyed the rover’s external calibration target with the miniature thermal emission spectrometer and acquired column 9, part 2 of the Bonestell panorama. To conserve energy, the rover did not relay data to Odyssey.

Sol 1520: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; measured atmospheric opacity caused by dust with the navigation camera (as well as the panoramic camera); and acquired movie frames in search of clouds with the navigation camera. The rover took spot images of the sky and surveyed the horizon with the panoramic camera. Spirit did not relay data to Odyssey.

Sol 1521: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; calibrated the elevation of the miniature thermal emission spectrometer; and acquired column 9, part 3 of the Bonestell panorama.

Sol 1522: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; took thumbnail images of the sky and surveyed the horizon with the panoramic camera; and acquired lossless-compression images of wind-blown deposits next to the rover with the hazard-avoidance cameras. Spirit did not relay data to Odyssesy.

Sol 1523: Spirit recharged the battery and did not relay data to Odyssey.

Sol 1524: (April 16, 2008): Spirit recharged the battery.

Odometry:

As of sol 1524 (April 16, 2008), Spirit’s total odometry remained at 7,528.07 meters (4.68 miles).


OPPORTUNITY UPDATE: Driving on Mars Is Hard - sol 1491-1497, April 03-09, 2008:

This week Opportunity demonstrated the challenges of operating a vehicle on the surface of another planet. The rover is en route to Cape Verde to acquire high-resolution images of the layering in the rocks. To get there, Opportunity must cross some sandy stretches. Before entering the sandy areas, Opportunity will need to stop and take a "toe dip’’ – that is, drive forward a short distance and back out again – to characterize the terrain.

On Sol 1491 (April 3, 2008), Opportunity performed a 4-wheel toe dip, driving forward until the front four wheels were on the sand and backing up again.

As part of ensuring vehicle safety, rover drivers set conservative limits on what the rover may do. For example, if Opportunity exceeds the maximum amount of wheel slippage or the maximum amount of tilt allowed, the rover must abort the drive. This gives the rover’s handlers a chance to further evaluate the situation and make changes to the drive plan on subsequent sols (Martian days). The toe dips provide valuable insight into the nature of the terrain Opportunity is likely to encounter on the way to Cape Verde.

Opportunity is healthy and all subsystems are performing as expected.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover’s high-gain antenna, sending data back to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1491 (April 3, 2008): Before the day’s drive, Opportunity took panoramic-camera and navigation-camera images of a previously made wheel scuff. The rover stowed the robotic arm and drove toward Cape Verde, taking hazard avoidance-camera images before and after ending the drive. Opportunity unstowed the robotic arm and acquired post-drive images with the navigation and panoramic cameras.

Sol 1492: In the early part of the sol, Opportunity took spot images of the sky for calibration purposes and surveyed the horizon with the panoramic camera.

Sol 1493: Opportunity monitored dust on the panoramic-camera mast assembly, stowed the robotic arm, and continued driving toward Cape Verde. Just before and after ending the drive, Opportunity took images of the area close to the rover with the hazard-avoidance cameras. The rover unstowed the robotic arm, took post-drive images with the navigation camera, and after communicating with Odyssey, obtained measurements of argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.

Sol 1494: Opportunity took thumbnail images of the sky with the panoramic camera and six movie frames in search of clouds with the navigation camera.

Sol 1495: Opportunity took spot images of the sky for calibration purposes with the panoramic camera, stowed the robotic arm, and drove toward Cape Verde. Before and after ending the drive, the rover took images with the hazard-avoidance cameras. Opportunity unstowed the robotic arm (known to engineers as the instrument deployment device) and acquired post-drive images with the navigation camera.

Sol 1496: In the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera and shot a 4-frame movie in search of clouds with the navigation camera. Opportunity stowed the robotic arm and drove backward onto bedrock to extract its wheels from the sand before proceeding toward Cape Verde. Before and after ending the day’s drive, the rover took images with the hazard-avoidance cameras. The rover then unstowed the robotic arm.

Sol 1497 (April 9, 2008): In the morning, Opportunity took thumbnail images of the sky with the panoramic camera and shot another 4-frame movie in search of clouds with the navigation camera. The rover acquired diagnostic images with the hazard-avoidance cameras and a mosaic of images of the work volume reachable by the robotic arm with the panoramic camera. When the evening Sun was low, Opportunity surveyed the sky with the panoramic camera. Plans transmitted to the rover for the following morning called for another 6-frame movie of potential clouds in the Martian sky.

Odometry:

As of sol 1497 (April 9, 2008), Opportunity’s total odometry was 11,689.21 meters (7.26 miles).