This image taken at NASA's Jet Propulsion Laboratory shows engineers rehearsing the sol 133 (June 8, 2004) drive into "Endurance" crater by NASA's Mars Exploration Rover Opportunity. Engineers and scientists have recreated the martian surface and slope the rover will encounter using a combination of bare and thinly sand-coated rocks, simulated martian "blueberries" and a platform tilted at a 25-degree angle. The results of this test convinced engineers that the rover was capable of driving up and down a straight slope before it attempted the actual drive on Mars.