Martian sand ripples are taller than Earth’s

New data gathered by a Mars-orbiting probe suggest that large ripples in sandy areas of the Red Planet are more than twice as tall as their terrestrial counterparts.

Single images taken from space rarely reveal the height of topographic features. However, by combining two orbital images taken from slightly different angles to create so-called stereo pairs of a region, researchers can calculate heights.

Kevin K. Williams and James R. Zimbelman of the Smithsonian Institution in Washington, D.C., analyzed stereo pairs garnered by the Mars Global Surveyor. Some regions revealed ripples 38 meters apart and 5.7 m high. On Earth, ripples with the same spacing reach only 2.5 m or so.

The taller sand ripples on Mars probably stem from a complex relationship among several factors, says Williams. Mars has a surface gravity that’s only about 40 percent that of Earth’s and a very thin atmosphere. Meanwhile, sand-moving winds on Mars can be much more intense than they are on Earth. The researchers presented their findings Nov. 3 in Seattle at the annual meeting of the Geological Society of America.

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