Today, the surface of Mars is an arid desert – but UCI and European researchers have found strong evidence that an ocean once covered part of the red planet. UCI Earth system scientist Jeremie Mouginot and colleagues analyzed more than two years of data collected via radar by the European Space Agency’s Mars Express orbiter. The craft detected sediments reminiscent of an ocean floor within the boundaries of areas previously identified as ancient shorelines on Mars. “We interpret these as sedimentary deposits, maybe ice-rich,” Mouginot said. “It is a strong new indication that there was once an ocean here.” To find evidence of life, astrobiologists will have to look even further back in Mars’ history, when liquid water existed for much longer periods.