Unless, that is, one could somehow peer deep beneath its frigid surface to the base of the ice cap some 1.5 kilometers below, where a lake of liquid water almost three times larger than the island of Manhattan may lurk.
What they believe to be a lake sits under the planet's south polar ice cap, and is about 20km across.
Also, the Martian soil is filled with magnesium, calcium and sodium salts, a mix that would have the effect of lowering the freezing temperature of water further still, to perhaps a minimum -60 degrees Celsius.
The hunt for evidence of past or present life on Mars has gotten a number of boosts in recent decades, including the discovery of what might be organic molecules in rock samples, but the biggest question on the minds of those who imagine the planet might have supported life is that of water. InSight is also the first mission dedicated exclusively to learning more about the planet's interior in an attempt to glean clues about how rocky terrestrial planets like Earth formed during the birth of the solar system 4.5 billion years ago. MARSIS surveyed Mars' Planum Australe region between May 2012 and December 2015 and utilized radar pulses, sending them through the surface and the polar ice caps, ultimately measuring how the radio waves came back.
"This subsurface anomaly on Mars has radar properties matching water or water-rich sediments", Roberto Orosei, principal investigator of the MARSIS experiment and lead author of the paper, said in a press release.
"This is the first body of water it has detected, so it is very exciting", David Stillman, a senior research scientist in the Department of Space Studies at Southwest Research Institute in Texas, told AFP in an email.
"For water to exist under the surface it has to be deep and really salty, and that last part is significant because that is exactly the type of place you go look for lifeforms".
Scientists may have found liquid water on Mars
The process requires a detailed understanding of the radar signals that were transmitted downward toward Mars by Mars Express . Salts in the lake are believed to have kept the water - which has a temperature as low as -68C (-90F) - from freezing over.
Twenty-two years later, as with every discovery of liquid water on another world, one inevitably asks: Is there life? "This finding would have profound implications on the potential biological evolution of the planet". Water is considered a fundamental ingredient for life.
But if water is still there, it would mean it has likely been constant throughout Mars' 4.6 billion year history - making the possibility of life much more likely.
According to early hypotheses, however, the lake is most likely too cold and salty to sustain any sort of life.
This find was made using the Mars Express spacecraft and its on board Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument.
"It will require flying a robot there which is capable of drilling through 1.5km of ice".
Dr Manish Patel from the Open University explains: "We have long since known that the surface of Mars is inhospitable to life as we know it, so the search for life on Mars is now in the subsurface". There are hundreds of this of subglacial lake on Earth, mostly in Antarctica.
Some experts are skeptical of the possibility since the lake is so cold and briny, and mixed with a heavy dose of dissolved Martian salts and minerals. The south polar layered deposits - layers of ice and dust - are seen to a depth of about 1.5 km. Subsurface echo power is color coded and deep blue corresponds to the strongest reflections, which are interpreted as being caused by the presence of water.