This result is based from methane readings taken by the ExoMars Trace Gas Orbiter and the Curiosity rover
Mars was much more Earth-like in its past than previously thought, Curiosity finds
Chemicals found in Martian rocks by the rover suggest the Red Planet once had more oxygen in its atmosphere than it does now
What would Martian life be like?
Astrobiologist Charles Cockrell tells us what creatures we might find on Mars