Cliffs in Ancient Ice

Scientists have come to realize that, just below the surface, about one third of Mars is covered in ice. We study this ice to learn about Mars' ancient climate and astronauts' future water supplies. Sometimes we see the buried ice because cliffs form like the one in this image. On the brownish, dusty cliff wall, the faint light-blue-colored ice shows through. Some of these cliffs change before our eyes and boulders of ice can tumble downhill.