Before, during, and after avalanches on Mars
Posted by Emily Lakdawalla
03-03-2008 16:46 CST
These are some amazing photos that I think pretty much speak for themselves. They contain billowing dust clouds tossed into the air just moments after an avalanche of dusty material cascaded down the steep slope at the edge of Mars' north polar cap. As usual for images from the HiRISE camera on Mars Reconnaissance Orbiter, I'm only showing you a tiny little bit of the entire image; you should visit the HiRISE website and use their "IAS Viewer" to check out and wander around the whole image and see what else you can find.That image shows two of the four avalanches the HiRISE team spotted in the full image; here's a third. Finally, the HiRISE team also pointed out the existence of a "before" image, the same area seen just two weeks prior. What they didn't mention was that the "before" image also contains at least one active avalanche! Here's a blink comparison between the two. Because HiRISE was looking at the area from different directions to take the two images, I couldn't line up all the landscape features -- the very steep slope is much more foreshortened in the "before" image than it is in the "after" view. But you can easily see where there is an avalanche near the bottom of the February 3 image and one near the top of the February 19 image. (Thanks to Astro0 on unmannedspaceflight.com for pointing this out!) The polar cap is one place where Mars scientists expect to see changes happen every season, as the winter deposits of carbon dioxide frost (the white stuff in these images) ebb and flow. But I don't think they expected to see avalanches actually happen! It serves as a reminder that although Mars is quite a bit slower-paced than Earth, it still has active geology.
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