The Curiosity rover discovered that the chemistry of ancient Mars could have supported simple microbes more than three billion years ago, about the time that life first arose on Earth, scientists from the National Aeronautics and Space Administration said Tuesday.

The scientists based their claim on a rock sample mined from Mars last month by NASA's $2.5 billion Curiosity rover, which has been exploring the planet since August. In the grit of fine-grained mudstone, the scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon