ON UNDER THE ROCKS: Mars hides thick sheets of ice just below the surface.

The newer Mars Reconnaissance Orbiter mapped the surface in greater detail. Dundas and his colleagues used its pictures to locate exposed ice in small craters, glaciers and ice sheets. “The high-resolution data has greatly improved our understanding of various ice-related land forms,” he said.

These cliffs are “rare peeks into the subsurface of Mars, giving us access to an undisturbed slice through Mars’s ice in the mid-latitudes — a fantastic find!” said Susan Conway, a planetary scientist at the University of Nantes in France who was not involved with this research.

That will come in handy.