An anonymous reader writes "The Mars rover Spirit has been inching carefully down the north slope of the feature 'Home Plate' to tilt its solar panels into the sun to survive the long Martian winter. On Friday, it reached a tilt of 29.9 degrees, probably the final tilt it will reach for the winter. Although it's used the tilt strategy to increase power over the Martian winter twice before, this year it's especially critical, since a global dust storm last summer has left the solar-powered rover covered with dust and starved for power. Geoffrey Landis, one of the MER scientists, commemorated Spirit's trek to the winter haven with a sonnet on his blog. (The second of the two rovers, Opportunity, is at a landing site that's not as far into the southern hemisphere, and hence has less need to find a tilted surface.) OSU has a website explaining some of the software used to visualize the terrain to optimize the tilt, and for the latest news, the ongoing log of the rover status is updated weekly."