But the origins of the gas remain unclear
Searching for signs of Martian life in the United Kingdom
A series of acidic streams in Dorset, United Kingdom, resemble Mars billions of years ago, which could help scientists find microbial life on Mars
VIDEO: Proton rocket reaches launchpad with Mars spacecraft
The Russian rocket prepares for blast off on Monday, carrying ExoMars 2016
What would Martian life be like?
Astrobiologist Charles Cockrell tells us what creatures we might find on Mars
All About Space issue 24 on sale today
Grab yourself a free preview of the latest issue of All About Space