Mars rover
Media playback is unsupported on your device

Mars rover finds evidence that the red planet was once habitable

19 July 2013 Last updated at 06:53 BST

Nasa's Curiosity rover has found strong evidence that Mars was once habitable.

Results of the most detailed analysis of the Martian atmosphere suggests that more than four billion years ago it was quite similar to Earth.

Pallab Ghosh reports.