The Lost Oceans Of Mars

Planetary scientists detected evidence of water relatively early on in the history of Mars exploration. As a study in Nature notes, the first glimpses of an ancient, watery Mars came when the planet was visited by NASA’s Mariner 9 space probe in 1971. Among the details it picked out on the surface of Mars were landscapes sculpted by water, some of which appeared to be caused by gargantuan floods in the distant past. NASA’s Viking 1 craft would touch down on the Martian surface soon afterward in 1976, and recent studies suggest that the barren, rock-strewn plain where it landed was itself shaped by enormous tsunamis in the distant past. Poor Mars, it seems, has had a violent history.

Mars has all the signs of a planet that used to have a lot of water on its surface, leading scientists to hypothesize what it might once have been like. In 1987, at the MECA Symposium on Mars, John Brandenburg formerly proposed the idea of a “paleo-ocean,” which is essentially a huge body of water that would have covered much of the planet’s global north back when it was still young. Brandenburg posited that, as the oceans began to freeze, aquifers along the shoreline would release their water onto the surface, causing tumultuous floods which left their indelible mark on the landscape. This seed of an idea would grow into decades of studies centered around water on Mars, both in the past and the present day.