The ice caps above the lake likewise increase pressure, impacting the melt point and potentially helping pave the way for a subglacial liquid water lake.
Given how the Martian landforms have shaped, with mountains and valleys and riverbeds, researchers have known that the planet held historically large waterbodies. Then, concerned that their hope the bright spots might be water could blind them to other explanations, Orosei and colleagues spent nearly as long trying to demolish their own data. Putting an end to decades of doubt and debates, scientists have finally found evidence that there is not just frozen water on the surface of Mars, there actually is a massive reservoir-like catchment of liquid water just under the surface of the red planet.
Between May 2012 and December 2015, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (or "MARSIS" for short) surveyed the region of Mars known as the Planum Australe, a 200-kilometer area on the planet's southern polar plain, which is composed of water ice, Carbon dioxide ice, and admixed dust. The liquid water is likely to be very salty and sludgy (briny). On Mars. And the new research is published in Science, one of the most legit journals around. The scan took place between May 2012 and December 2015. These waves dig into the icy shell and soil, and travel down until they encounter geological structures before bounding back to the craft.
It's been tricky arriving at this conclusion. Up until 2010 or 2011, Pettinelli said, scientists weren't sure if the signal was due to a problem with the radar or something under the ice. "The problem is that this water is located 1.5km underneath the South Pole, so there is an very bad lot of ice to be drilled to before you reach this liquid water", he added.
Whether below an Earthly glacier or a Martian ice cap, the mechanism for melting is much the same: heat trickling up from below combines with the enormous bulk of an insulating blanket of material pressing down from above to form lakes of meltwater. He suspects Mars may contain other hidden bodies of water, waiting to be discovered.
The potential body of water
"This water would be extremely cold, right at the point where it's about to freeze".
Several researchers said it would be crucial to figure out whether this body of water is the only one, or part of an interconnecting body of underground aquifers - in part because a network increases the possibility it could have harboured life. "It's the kind of signal we would expect for liquid water". It is a prime candidate for habitability anywhere and the presence of water in general attracts a lot of attention for planetary missions. On Earth those lakes are often connected by channels, forming branching riverlike networks of water that extend across vast spaces beneath the ice. Certain materials, like dry rocks or CO2, have low permittivity while others, like liquid water, produce high values.
"We discovered water on Mars", says Roberto Orosei, a researcher with the Italian National Institute for Astrophysics (INAF). For the first time, there were images of an alien world, one that the inhabitants of Earth knew basically nothing about.
Not all's impossible, though. Future missions with more advanced technology will undoubtedly help solve the water on Mars mystery.
The discovery was made by Italian scientists who were analysing images from the the Mars Express spacecraft - a European satellite.
There is no reason to conclude that the presence of subsurface water on Mars is limited to a single location.