NASA/JPL-Caltech/MSSS
Just below the surface, Mars is full of ice. New observations have revealed steep cliffs cut out of thick sheets of ice, which may be able to tell us about the planet’s climate over the past millions of years.
We know from previous radar studies that ice abounds just under Mars’s dusty surface, but where exactly it is in the Martian crust or how deep it goes is still unclear.
Colin Dundas at the US Geological Survey in Flagstaff, Arizona and his colleagues examined pictures from the Mars Reconnaissance Orbiter and found eight ice patches in steep cliffs, which formed as ice accumulated over millions of years just under the Martian surface. Erosion revealed these icy blue spots, and they’re still visible today.
The ice sheets start less than a metre below the surface and the team estimates that they are at