Mars's Polar Canyon
Mars's Polar Canyon
Image courtesy NASA
The swirling troughs of Mars's north polar ice cap are seen above in a recently released picture from the no-longer-operating Mars Global Surveyor orbiter, whose mission was terminated in 2007.
Hidden by a permanent layer of ice, the subsurface features that gave rise to these troughs—including the giant Chasma Boreale, a rift about the same length as the Grand Canyon—have long been shrouded in mystery.
But now radar data from the Mars Reconnaissance Orbiter have helped astronomers bisect a region of ice 1.2 miles (2 kilometers) thick and 155 miles (250 kilometers) across. The readings show how thin layers of ice bulge and tilt in relation to each other, which offers clues to the shape of the underlying ice sheet.
Published June 1, 2010
