ChemCam findings hint at oxygen-rich past on Mars

The discovery of manganese oxides in Martian rocks might tell us that the Red Planet was once more Earth-like than previously believed. A new paper in Geophysical Research Letters reveals that NASA's Curiosity rover observed high levels of manganese oxides in Martian rocks, which could indicate that higher levels of atmospheric oxygen once existed on our neighboring planet. This hint of more oxygen in Mars' early atmosphere adds to other Curiosity findings—such as evidence of ancient lakes