Continuing our impact related theme of the past two days, a new discovery has been made on Mars that incoming meteors large enough to create craters are also causing dust avalanches. The avalanches are caused by the shockwave that precedes the incoming impactor which is traveling at several times the speed of sound. Because the Martian atmosphere is not as dense as Earth's, a lot of meteors that would burn up in our atmosphere survive on Mars to create new craters.
From the University of Arizona Press Release, "Each year, about 20 fresh craters between 1 and 50 meters (3 to 165 feet) show up in images taken by the HiRISE camera on board NASA’s Mars Reconnaissance Orbiter. The High Resolution Imaging Science Experiment, or HiRISE, is operated by the UA’s Lunar and Planetary Laboratory and has been photographing the Martian surface since 2006, revealing features down to less than 1 meter in size. For this study, the team zoomed in on a cluster of five large craters, which all formed in one impact event close to Mars’ equator, about 825 kilometers (512 miles) south of the boundary scarp of Olympus Mons, the tallest mountain in the solar system. Previous observations by the Mars Global Surveyor orbiter, which imaged Mars for nine years until 2006, showed that this cluster was blasted into the dusty surface between May 2004 and February 2006."
In looking at the HiRise images of the crater cluster there were a large number of dust avalanches observed, over 64,000. The "ah-hah!" moment came when one photo showed a pair of scimitar-shaped features were seen which were subsequently shown to precisely fit computer models of the blast wave.
Read More About It: http://uanews.org/node/43798.
Sky Guy in VA
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