Mars may conceal giant reservoirs of liquid water underneath its dusty surface, which future explorers might one day tap for long-term expeditions on the red planet. “What a perfect medium for life on Mars,” added Mars expert Bill Hartmann at the Planetary Science Institute in Tucson, Ariz. “These findings may have huge implications for the search for life there.” Evidence for underground aquifers is found in decades-old pictures of craters taken by the Mars Viking Orbiter, reports a research team led by Nadine Barlow of the University of Central Florida in Orlando. These craters, ranging from 5 to 50 kilometers (3 to 30 miles) in diameter, were blasted out from Martian soil by impacts with meteors. Scientists have suggested the patterns in the ejecta — the debris around the impact craters — indicate the presence of water underground.