New findings from NASA's Curiosity Rover provide evidence that significant amounts of oxygen once permeated the atmosphere of ancient Mars. The Red Planet, it would seem, was more Earth-like than we thought. Using the ChemCam instrument atop Curiosity, scientists at the Los Alamos National Laboratory have discovered high levels of manganese oxides in Martian rocks. The rover made the discovery in mineral-filled cracks in sandstones in the Kimberley region of Gale crater. The presence of this chemical element suggests that high levels of free-floating oxygen once existed on Mars, and that in addition to having a warmer climate and lakes of liquid water, this planet was once quite Earth-like in terms of its chemical composition. But where did all this oxygen come from, and where did it all go? Lanza's team hypothesizes that oxygen seeped out of the planet's water and into the Martian atmosphere as Mars' magnetic field collapsed. Without a magnetic field to protect the surface from