Is there life on Mars?
David Bowie sang a good song about it back in the Seventies, but NASA scientists are reporting that the presence of methane on Mars could actually signal life.

Methane can only live for a short time in the Martian atmosphere which means the gas must be constantly replenished - and that only leaves two options:
1. active volcanoes (none of which have been found yet on Mars)
2. microbes
BBC