
This is actually kind of a big deal, if it proves true; there may be a lake of liquid water on Mars, under the south polar cap. Excerpt:
A lake of liquid water has been detected by radar beneath the southern polar ice cap of Mars, according to a new study by Italian researchers from the Italian Space Agency, published Wednesday in the journal Science.
Evidence was gathered by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument, also known as MARSIS, on the European Space Agency’s Mars Express spacecraft.
Between May 2012 and December 2015, MARSIS was used to survey the Planum Australe region, which is in the southern ice cap of Mars. It sent radar pulses through the surface and polar ice caps and measured how the radio waves reflected back to Mars Express.
Those pulses reflected 29 sets of radar samples that created a map of drastic change in signal almost a mile below the surface. It stretched about 12.5 miles across and looked very similar to lakes that are found beneath Greenland and Antarctic ice sheets on Earth. The radar reflected the feature’s brightness, signaling that it’s water.
“We interpret this feature as a stable body of liquid water on Mars,” the authors wrote in the study.
The study authors ruled out any other causes for this brightness.

No word on thoats, Tharks, or beautiful Martian princesses clad only in jewels.
So, why is this a big deal? Two reasons: The possibility of life, and the possibility of human colonization.
As I’ve said before, the discovery of any life outside of Earth, even microbes, would be the biggest scientific discovery of the modern era. There are other places where it’s possible; some folks think the Venusian atmosphere could harbor extremophile microbes, as could the oceans of Titan, Enceladus and Europa. Of course, the amount of evidence for such life remains as it was – zero. But liquid water is a prerequisite for life as we know it, and there it is.
Of more likely import is the establishment of a human colony on Mars. Liquid water makes that easier; water can provide fuel and oxygen in addition to its traditional uses.
Of course, there are still massive engineering challenges to overcome before people could live on Mars, and the lighter Martian gravity would result in some pretty odd-looking specimens of humanity after a generation or two.
Still, it’s an interesting find.