Unearthly dunes

Slow-moving landforms in Alaska decipher the frigid surface of Mars.


IN 1972, scientists eagerly awaited images from NASA Mariner 9 as it mapped the surface of Mars for the first time. The orbiter sent back thousands of images of craters, canyons, and fields of sand dunes. Succeeding NASA missions took more photos of the Red Planet over the next thirty-five years. But these missions yielded more images of unmoving landscapes. Although fascinating and a source of new research for many scientists, the images of these still landforms disappointed geomorphologists, who study land surfaces and the processes that shape them. “On Mars, we are always looking for signs of active surface processes like erosion, or evidence of wind and water–any sign of something happening on the planet today,” geologist Donald Hooper said.

Then in 2008, researchers looked more closely at the images that the Mars Global Surveyor took of the planet’s north polar region, and found dunes that shrank or completely disappeared over three Martian years (six Earth years). Curiously, the surrounding dune field showed no other changes. “Since that discovery, scientists have wanted to know whether the surrounding dunes are also active,” Hooper said. With sparse data on Mars, scientists turned to sand dunes on Earth, to gain insight that would help them study and interpret dunes on Mars. They chose a location that is most similar to the north polar dune fields of Mars: the Great Kobuk Sand Dunes in Alaska.

Originally published in Sensing Our Planet: NASA Earth Science Research Features. Read the full story here.

Image courtesy U.S. National Park Service.