http://www.jpl.nasa.gov/mer2004/daily/3-5-04.cfm Opportunity Status for sol 40 Opportunity Fit at Forty posted Mar. 5, 12:15 pm PSTAfter 40 good days on the surface, Opportunity is showing no signs of middle age. On sol 40, which ended at 9:32 a.m. PST, March 5, 2004, Opportunity finished a set of overnight alpha particle X-ray spectrometer measurements at "Last Chance" and completed a morning set of panoramic camera and miniature thermal emission spectrometer remote sensing observations. At 11:30 Local Solar Time, engineers retracted the alpha particle X-ray spectrometer off the target, took a final set of 24 microscopic images, and stowed the arm for driving. Opportunity then scored another first by successfully using visual odometry to navigate autonomously on Mars. During a drive along the crater wall, the vehicle properly identified wheel slippage on the steep slope of the crater wall using features in the navigation camera imagery. This effectively provided a mid-course correction that landed the science and engineering team exactly at the target location where they want Opportunity to do work using the instruments on the rover arm on sol 41. The plan for sol 41, which will end at 10:12 a.m. PST, March 6 will be to take microscopic images of an area dubbed "Wave Ripple" in the "Last Chance" area, followed by a traverse to "Slick Rock" in the "Berry Bowl" area.