Spirit is heading toward the summit of "Husband Hill." The rover has been making slow progress recently due to slippage on new, sandy terrain, but it is persevering to reach the target. The rover team performed image brightness tests with the navigation camera to assess how late in the sol Spirit can use sunlight for imaging.
Sol-by-sol summaries:
Sol 436 (March 25, 2005): Spirit took panoramic camera images of areas dubbed "Cottontail" and "Blanket." The rover also completed a 24-meter (79-foot) drive.
Sol 437: Spirit took some post-drive images and performed other remote sensing. It took a sky survey, measured the opacity of the atmosphere, and looked for dust devils.
Sol 438: Spirit did a lot of remote sensing on sol 438, taking three surveys of the sky, measuring the opacity of the atmosphere, searching for dust devils, and looking for clouds.
Sol 439: Spirit drove 3 meters (10 feet). It also conducted an image brightness test with its navigation camera. The rovers can't take images when it is too late in the sol since they use the natural light from the Sun to illuminate features on Mars. The rover team experimented with taking pictures later and later this sol. Currently, the rover team does not usually take pictures after long drives, but if the images taken later in the sol come back clear and useful, then the team will start commanding the rover to take images later in the sol, after drives.
Sol 440: Spirit completed a 1.7-meter (5.7-foot) drive.
Sol 441 (March 31, 2005): The rover completed a 2.28-meter (7.48-foot) drive. On the new terrain that Spirit has reached, the rover slipped 45 percent on an 11-degree slope. In the past, when Spirit was on an 11-degree slope, the rover did not slip as much, but this terrain is much sandier than previous terrain Spirit has driven on. The rover used to have a slip limit at 40 percent, so the rover would automatically shut off if it slipped that much. The rover team increased the allowable slippage to 60 percent to enable the rover to progress and move forward.