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als RSS Feed abonnieren📚 Giant Waves of Sand Are Moving On Mars
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🔗 Quelle: science.slashdot.org
"Researchers have spotted large waves of martian sand migrating for the first time," reports Science magazine. "The discovery dispels the long-held belief that these 'megaripples' haven't moved since they formed hundreds of thousands of years ago. They're also evidence of stronger-than-expected winds on the Red Planet." It's pretty staggering that humans can detect these changes on Mars, says Ralph Lorenz, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory who was not involved in the research. "We can now measure processes on the surface of another planet that are just a couple times faster than our hair grows...." Since the early 2000s, Mars rovers and orbiters have repeatedly spotted megaripples on the Red Planet. But they didn't seem to change in any measurable way, which led some scientists to think they were relics from Mars's past, when its thicker atmosphere permitted stronger winds. Now, using images captured by NASA's Mars Reconnaissance Orbiter, Simone Silvestro, a planetary scientist at Italy's National Institute of Astrophysics in Naples, and his colleagues have shown that some megaripples do creep along — just very slowly. The researchers focused on two sites near the equator of Mars... Megaripples in both regions advanced by about 10 centimeters per year, the team reports in the Journal of Geophysical Research: Planets... It's a surprise that megaripples move at all on Mars, says Jim Zimbelman, a planetary geologist at the Smithsonian Institution's Air and Space Museum. Just a few decades ago, there was no evidence that sands on Mars were mobile, he says. "None of us thought that the winds were strong enough...." Atmospheric models of Mars suggest winds capable of moving sand are rare. This discovery of migrating megaripples will force those models to be revised, the team suggests.... Megaripples on the move are beacons of windy conditions, which might in turn kick-start dust storms, the researchers suggest. Airborne dust can blanket solar panels, reducing their efficiency, and it can also gum up mechanical parts like gears. That's bad news for Mars rovers and human habitats alike.
Read more of this story at Slashdot.
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