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The Dunes of Mars
Story by Laurel Hamers on March 15, 2016
图1
Images of windswept dunes taken from orbit provide a tantalizing peek into Martian weather.
The surface of Mars is covered by constantly shifting sand blown by the planet’s winds. This creates an ever-evolving desert landscape with diverse and striking dunes. Loose mounds of sand are found all over Mars, ranging in height from a few dozen feet to higher than some of Earth’s tallest skyscrapers. Over the past 10 years, images taken by the HiRISE instrument aboard NASA’s Mars Reconnaissance Orbiter spacecraft have allowed scientists to study Mars’ dunes in unprecedented detail. The enhanced-color views captured from orbit reveal characteristics of their shape, composition, and movements over time, giving clues about the planet’s dynamic atmosphere and current climate. The speeds and directions of Mars’ regional wind patterns, for example, can be estimated by how quickly a dune’s shape changes. Because dune movements erode and expose rock formations that might host ancient habitable environments, understanding the planet’s winds could help researchers identify landing sites for future exploration. Explore the images to learn more.
图2
Mars' dunes are classified by shape. Star dunes (above) have a central peak with three or more arms formed by winds blowing from many directions.
图3
Linear dunes (above) are sculpted by winds blowing from one or two slightly different directions, and can extend for more than 100 miles.
图4
Barchans (above) are crescent-shaped dunes formed by winds traveling in one direction. The crescent's two ends point in the direction of the wind.
图5
The HiRISE instrument aboard the Mars Reconnaissance Orbiter spacecraft has collected images of Mars since 2006.
