Since arriving at the rover's current location on the 807th sol, or Martian day, of exploration (April 10, 2006), Spirit's knowledge of its attitude relative to the sun has drifted. The rover uses an onboard computer to keep track of attitude changes, but error builds up in this measurement over time. On sol 855 (May 30, 2006), rover planners transmitted an attitude update of 1.97 degrees to correct for the drift. After the update, Spirit re-acquired images from the same location to allow the science team to accurately target future observations.
Meanwhile, Spirit continued acquisition of the "McMurdo panorama" and removed another 2 millimeters of soil as part of a layer-by-layer soil study.
Sol-by-sol summaries:
Sol 855 (May 30, 2006): Spirit completed a quick get-fine attitude, which is a procedure completed every couple of weeks to correct any error in the rover's knowledge of its attitude relative to the sun. Spirit also took a 360-degree view of its surroundings with the navigation camera and a forward-looking view through the front hazard avoidance camera. The rover conducted remote sensing with the miniature thermal emission spectrometer during the overhead pass of the Mars Odyssey spacecraft.
Sol 856: Spirit acquired column 16 (a one-by-five mosaic) of the McMurdo panorama.
Sol 857: Spirit spent 80 minutes brushing away another 2 millimeters of soil from the soil target "Progress." This layer of the study is known as "Progress 3."
Sol 858: Plans called for Spirit to take microscopic images of Progress
3, conduct remote sensing with the miniature thermal emission spectrometer during the afternoon overhead pass of the Odyssey spacecraft, and take two panoramic-camera images during the Martian sunset.Sol 859 (June 3, 2006): Plans call for Spirit to acquire column 17 (a one-by-three mosaic) of the McMurdo panorama.
Odometry:
As of sol 857 (June 1, 2006), Spirit's total odometry remained at
6,876.18 meters (4.27 miles).------------------------------------------------------------------------
OPPORTUNITY UPDATE: Digging Out of the Dune - sol 833-837, June 1,
2006:Opportunity is less than a kilometer (just over half a mile) from "Victoria Crater." During the last planned drive on sol 833, the rover became embedded in a soft dune. As designed, the drive was stopped by a slip check. The extraction process began on sol 836, with 5 meters (16 feet) of commanded motion, and 9 centimeters (3.5 inches) of actual forward progress. The results are encouraging, and extraction will continue on Friday (June 2, 2006) and over the weekend if necessary. Opportunity is otherwise healthy and continues to conduct atmospheric and targeted remote sensing on the path south.
Sol-by-sol summaries:
Sol 833 (May 28, 2006): For this sol, the team planned a drive of about
30 meters (98 feet), post-drive imaging, and atmospheric remote sensing. The drive started with a small turn in place to move to the center of a dune trough. The material the rover is in is soft, and the rover experienced very high rates of slippage. A slip check precluded further driving.Sol 834: On this second sol of a two-sol plan, Opportunity performed some atmospheric remote sensing (including cloud imaging) and recharged the batteries.
Sol 835: Opportunity took a break from driving and collected high-resolution images to better characterize the material in which the rover is embedded.
Sol 836: After evaluating the tracks and soil, the team began the extraction process. Five meters (16 feet) of driving was commanded, with limits imposed on rover tilt, mobility suspension angles, pitch, yaw, and total distance traversed. The drive resulted in 9 centimeters (3.5 inches) of forward progress. This is more than three times the rate of progress experienced during the "Purgatory Dune" extraction in April and May 2005. Hazard avoidance camera images also show that the front cleats are not as caked as during the Purgatory extraction.
Sol 837 (June 1): Plans called for the dune extraction to continue on this sol, with 10 meters (33 feet) of commanded motion. The sol 836 mobility safety checks were used. In addition, the allowable yaw range was narrowed, and the drive sequence also imposed a new limit for maximum visual odometry failures. Since visual odometry is likely to fail if more than expected progress is made, this will prevent the rover from traveling too far if it should happen to break free of the dune.
As of sol 836, Opportunity's total odometry is 7971.42 meters (4.95 miles).