Source 1
http://science.sciencemag.org/content/early/2018/07/24/science.aar7268.full[/link]
Quote (Source 1)
The presence of liquid water at the base of the martian polar caps has long been suspected but not observed. We surveyed the Planum Australe region using the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument, a low-frequency radar on the Mars Express spacecraft. Radar profiles collected between May 2012 and December 2015 contain evidence of liquid water trapped below the ice of the South Polar Layered Deposits. Anomalously bright subsurface reflections are evident within a well-defined, 20-kilometer-wide zone centered at 193°E, 81°S, which is surrounded by much less reflective areas. Quantitative analysis of the radar signals shows that this bright feature has high relative dielectric permittivity (>15), matching that of water-bearing materials. We interpret this feature as a stable body of liquid water on Mars.
Source 2
https://physicsworld.com/a/liquid-water-discovered-beneath-mars-south-pole/[/link]
Quote (Source 2)
The water below the ice cap must be at least tens of centimetres deep for MARSIS to detect, but it is not clear whether the body of water exists as a deep lake, like Lake Vostok on Earth, or as a shallow layer. Anja Diez, of the Norwegian Polar Institute, points out that all options are currently on the table, since Antarctic sub-glacial pockets of liquid water can come in many forms. “In Antarctica the water can exist because the temperatures below the kilometre-thick ice can reach melting point,” she says. On Mars the temperatures below the ice cap are much lower but, according to Diez, the liquid water could instead exist as a brine that would lower the freezing point of the water.
The existence of brine on Mars is likely because of the existence of perchlorate salts. In 2008, NASA’s Phoenix Mars lander found magnesium, calcium and sodium perchlorate in the Martian topsoil, and it has since been found to be widespread across the red planet. While the exact temperature of the discovered liquid water is unknown, laboratory experiments have shown that in some conditions briny water can remain liquid down to –70°C.
This was hypothesized in the 80's and it's a known fact there is an Ice cap on the Martian south pole so it's not a far stretch to think there could be water. But now we have what appears to be definitive proof.
Source 1 has a lot of detail as to how they collected and processed the information that led them to this conclusion. Not to mention citations and credits to all parties involved.
Source 2 is easier to read and just cuts to the nitty gritty without all the technobable.
Guaranteed to find some really old microbial ecosystems under that ice. Maybe even Martian worms.
This post was edited by Ep0ch on Jul 25 2018 08:44am