Martian ice has a thin skin. The newly discovered exposure of ice on steep banks suggests that the Red Planet’s ice sheets are buried by just a meter or two of soil, researchers report in Science January 12.
“What’s new and exciting here is that these ice sheets start quite shallowly,” says planetary scientist Colin Dundas of the U.S. Geological Survey in Flagstaff, Ariz. That could be good news for future astronauts hoping to use that water to drink, or to create oxygen to breathe or make fuel for returning spacecraft (SN: 1/20/18, p. 22).
Dundas and his colleagues used the Mars Reconnaissance Orbiter satellite to observe eight regions where steep slopes called scarps seem to reveal ice. In 2008, the Phoenix Mars lander revealed ice in regions close to the planet’s north pole (SN Online: 6/20/08). But these scarps were closer to the equator, at latitudes of about 55° north or south.
High-resolution images showed that the ice is organized into thin layers. Dundas says these layers probably originated as snowfall millions of years ago, when the north pole pointed in a different direction.
“It’s essentially giving a cross section through recent history,” Dundas says.
The researchers also saw large boulders that appear to have emerged from the ice, suggesting that erosion is making the ice sheets retreat by about a few millimeters every year.
The scarps themselves are so steep that it would probably be dangerous for humans or rovers to land there. “It’s not necessarily that these specific sites are where you would go,” Dundas says, but they’re useful for learning more about where ice may be found.