“During the next 2062 sols, NASA’s Mars Exploration Rovers traversed the surface of the Red Planet with the objective of determining if Mars was once wet.” In a new study, Professor de Souza revisited data collected by the MIMOS II spectrometer, which can identify iron-bearing minerals by measuring how iron atoms in a sample absorb gamma rays. The consolidated spectrum pointed to the presence of common Martian soil minerals such as olivine and pyroxene, along with a poorly crystalline, paramagnetic iron-bearing phase. “One of the most important discoveries was finding crystalline hematite in ordinary Martian soil,” Professor de Souza said. “This mineral’s widespread presence suggests not only that water was present, but that significant areas of Mars may have once been covered by water.”