Sojourner. Mars Pathfinder 360 degree panoramic mosaic view of the robotic Sojourner rover vehicle on the surface of Mars by the large rock called Yogi". Sojourner's Alpha-Proton X-Ray Spectromet- er (APXS) studied the composition of "Yogi" by bombarding it with alpha radiation & monitoring the particles released in response. Sojourner's circular tracks are from its soil mechanics exper- iments. The rover weighs 9 kilogrammes & is power- ed by a solar panel. An operator on Earth decides Sojourner's destination, but the rover itself chooses the best route. Image taken by the Imager for Mars Pathfinder (IMP) on the 8th, 9th & 10th Martian days since it landed on 4 July 1997."