Mars Sojourner, 1996.
© Science Museum / Science & Society Picture Library
Full size replica. Launched in 1996, NASA's Pathfinder mision was planned as a low cost means of sending scientific instruments, including the Sojourner micro-rover, to Mars. Sojourner was an experiment in itself, to determine how such a vehicle would cope with the harsh weather conditions and terrain of the Martian surface. It was also equipped to take pictures of its surroundings and to analyse the chemical composition of soil and rocks. Roughly the size of a microwave oven, the rover was powered by a solar panel and could move around at about 1 mph, controlled remotely by scientists on Earth. Sojourner was deployed on 4th July, 1997, with the expectation of operating for a week, but in fact continued to function for twelve times longer than anticipated.