Mars rover. Computer artwork of the micro-rover vehicle Sojourner on the surface of Mars. Sojourner was carried to Mars by the Mars Pathfinder spacecraft, which landed on 4th July 1997. The rover weighed about 9 kilograms, was 63 centimetres (cm) long and 48cm wide. It was powered by a solar panel (on top of its body) which allowed a few hours movement per day, and it was controlled by an operator on Earth. Sojourner studied rocks on the surface of Mars using its alpha-proton X-ray spectrometer (APXS) and a high-resolution camera. Sojourner's studies also provided extensive engineering data toward the design of future planetary rover vehicles.