Martian Samples Risk Earth Contamination in Search for Life

NASA's upcoming Mars 2020 rover is designed not only to hunt for signs of life on the Red Planet, but also to collect samples that might one day get returned to Earth. However, whereas Curiosity sought to find out how habitable Mars once was — that is, how capable it was of supporting life as it is known on Earth — "the motivating aspect of the Mars 2020 mission is astrobiology: to look for biosignatures, the signatures of life," according to Kenneth Farley, a project scientist for t