Nasa is looking for space enthusiasts to help it find and classify craters on Mars. Scientists at the American space agency’s Ames Research Center want to recruit “clickworkers” who are happy to spend time looking through a series of images of the Martian surface and rating the craters they find. Nasa is turning to people to do the job because they tend to be more discriminating than computer software designed for the same task. If the pilot project proves successful, the clickworkers could be asked to help the agency process the huge amounts of data from Nasa’s present and future Martian probes.