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The Strangely Beautiful Sand Dunes of Mars


Sand Dunes in Proctor Crater
NASA's Mars Global Surveyor spacecraft orbiting overhead in September 2000 recorded this picture of the oddly pretty sand dunes created by winds blowing in the Proctor Crater on Mars. The crater is named for 19th Century British astronomer Richard A. Proctor.

More defrosting dune pix:
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Over 26 Days »
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Recent Wind Action »
We've known about the exotic sand dunes on Mars since 1972 when NASA's Mariner 9 spacecraft sent home photos of their interesting shapes.

Launched from Earth in 1971, Mariner 9 was the first artificial satellite of Mars. It transmitted data and images to Earth from martian orbit for nearly a year. The probe's final transmission was in 1972.

NASA had been exploring Mars with its Mariner series of spacecraft in the 1960s and 1970s. Mariner 9 marked the transition in exploration of the Red Planet from flying by the planet to spending time in orbit around it.

Awaiting a clear day. A great dust storm obscured the whole planet beneath it as Mariner 9 arrived at Mars. Ground controllers on Earth sent commands to the spacecraft to wait for the storm to die down. When the dust finally settled after a month, a clear view of the surface revealed a very different planet than astronomers had expected.

What they saw were gigantic volcanoes and a grand canyon stretching 3,000 miles across the planet's surface. Relics of ancient riverbeds were carved in the landscape of a dusty, dry planet. Mariner 9 went on to map the entire surface of the planet. It sent home the photos of Proctor Crater in February and March 1972.

Sand dunes. A sand dune is a mound, hill or ridge of loose wind-driven sand heaped up on Earth in hot deserts and along sandy seashore and lake coastlines, and along some river valleys.

Dunes discovered. Amidst the surprises and curiosities of the martian landscape, Mariner 9 spotted a fascinating field of sand dunes in a place known as in Proctor Crater. Recently, they have been photographed by the Mars Global Surveyor satellite orbiting above the Red Planet.

Proctor Crater is a 106-mi.-wide bizarre place named for 19th Century British astronomer Richard A. Proctor.

Active today. Mars Global Surveyor images show the Proctor Crater dunes are active today. Its pictures depict dark sand dunes with bright patches of southern winter frost. Dark streaks on the frost-covered slopes are a result of recent avalanches of sand on the steep down-wind "slip face" sides of the dunes.

Because the dark sand streaks are superposed upon the bright frost, the streaks can only be as old as the frost. This frost cannot be more than eleven months old. That tells scientists that the dunes must be active today in order to show such streaks. A year on Mars is 669 Earth days.

Changing rocks. By observing changing patterns in the dunes, scientists learn about the interaction between the Martian surface and the atmosphere. The fascinating dune activity helps them understand how the Martian wind moves sediments around. Then they can estimate how long it takes for windblown sand to wear down the surfaces of rocks.

Sand dunes at various locations around Mars appear striking, peculiar, even weird. Some dark dunes have been said to look like shark's teeth or Hershey's Kisses chocolate candy. In reality, they are mounds of sand rising from the complex relationship between the sandy surface and high winds on Mars.
Dune Activity in Proctor Crater  »

Backstage. The Mars Global Surveyor (MGS) spacecraft's Mars Orbiter Camera (MOC) was built by the California Institute of Technology and Malin Space Science Systems (MSSS) using spare hardware left over from the failed Mars Observer spacecraft lost in 1992. MSSS operates the camera from its facilities in San Diego, California. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California, and Denver, Colorado.

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Sand dunes: Dust Storms: Air: Carbon Dioxide: Outflow Channels: Valley Networks: Rift Valley: Water: Artesian Water: Ice: Ice caps: Frost: Mars Weather: Mars Photo Galleries: Planet features: Canals: Rocks: Mountains: Dating and aging: Seasons:
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