Mars's Atmosphere Used to be Thicker. Has Curiosity Found Where it All Went?

Planetary scientists have plenty of theories about Mars and its environmental past. Two of the most widely accepted are that there was a carbon dioxide atmosphere and, at one point, liquid water on Mars' surface. However, this theory has a glaring problem: Where should the rocks have formed from the interactions between carbon dioxide and water? According to a new paper by scientists at several NASA facilities using data collected by the rover Curiosity, the answer is right under the rover's metaphorical feet.