Located at the edge of a more than three-billion-year-old ice cap covering Mars’s south pole, the region known as Planum Australe would rank high on any list of the Red Planet’s least-interesting locales. Frozen, flat and featureless, it seemingly offers little more than windblown dust and drifts of crystallized carbon dioxide for any aspiring explorer to see. Unless, that is, one could somehow peer deep beneath its frigid surface to the base of the ice cap some 1.5 kilometers below, where a lake of liquid water nearly three times larger than the island of Manhattan may lurk.

Discovered by a team of Italian scientists using three year’s worth of data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on the European Space Agency’s Mars Express orbiter, the potential lake is at least a few meters deep, and might be a fixed, steady feature of the subsurface. If confirmed, this would be the first-known reservoir of liquid water on present-day Mars—a keystone in the search for past or even present life on the Red Planet, potentially offering fresh clues about how Earth’s neighbor so profoundly transformed billions of years ago from a warmer, wetter world to its current freeze-dried state. Announced today at a press conference in Rome, the results are detailed in a study appearing in the July 26 edition of Science. Although this is just one detection, the team wrote, “there is no reason to conclude that the presence of subsurface water on Mars is limited to a single location.”

To read more, click here.