'Best chance yet to detect life's traces on Mars'

The US space agency (Nasa) will launch another sophisticated rover to the Red Planet this year. Codenamed Mars 2020, the robot will find, categorise and cache rock and dust samples for later return to Earth. The hope is these samples will contain clues to the existence (past or present) of life. Katie Stack Morgan, the deputy project scientist on the mission, spoke with our science correspondent Jonathan Amos.