‘Is there life on Mars?,’ asked David Bowie, and would not stay for an answer. The astrobiologist Steven Benner has an answer – which is that Mars not only has had life but still does. Benner describes how the Viking mission in 1976 intended, among other priorities, to detect life. Gerald Soffen, the mission’s chief scientist, declared: ‘That’s the ballgame, no organics on Mars, no life.’ It’s much safer to insist that there is no life on Mars than to suggest that there is and be proved wrong.