In 2018, planetary scientists made an astonishing claim: They had found a large lake of liquid water under the surface of Mars near the Martian south pole.
The evidence was pretty striking, but not quite 100% convincing.
In a new paper, the same team of scientists announce that they have collected more data, reanalyzed what they had before, and not only do they say it strengthens their earlier claim, but they have also found three more lakes under the frozen Martian surface!
So, yeah, this is very exciting.
The data come from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), an instrument about the ESA's Mars Express spacecraft, which has been orbiting the red planet since late 2003. It sends pulses of radar to the planet below, which reflects them back up. Different materials reflect the radar with different efficiencies, so that scientists can get an idea of the kinds of stuff on the surface.
But, these pulses can also penetrate fairly deeply into the ground before being reflected, and that allows scientists to literally get a picture of material below the surface.
A spectacular mosaic of the south polar region of Mars, taken by Mars Express in ...