Meteorites traveling towards the surface of Mars can often be traveling at several times the speed of sound as they hit the planet's thin atmosphere. A new study of images taken from NASA's Mars Reconnaissance Orbiter (MRO) suggests the hurtling rocks trigger shockwaves that roll through the air actually triggering avalanches on the dusty surface before they strike.
The images from the MRO show dark streaks that resemble scimitar or crescent shapes that did not fit patterns researchers expected from seismic shaking caused by impact. Instead they bore the signature one would expect from a shockwave.
When the team ran computer models to simulate the geologic features of a shockwave, the hunch paid off. The results showed the same exact same characteristics of those from the images on the surface of Mars.
University of Arizona undergraduate student Kaylan Burleigh, who led the research project, said, "Those scimitar tipped us off that something other than seismic shaking was causing the dust avalanches."
With Mars' atmosphere 100 times less dense than that of Earth, it can't protect the surface from even the smallest meteors. In fact, scientists report about 20 new impact craters between three and 165 feet across each year as it regularly gets pummeled. The shock wave induced avalanches bring an added understanding to the havoc the space rocks can bring.
"This is one part of a larger story about current surface activity on Mars, which we are realizing is very different than previously believed," said Alfred McEwen, principal investigator of the HiRISE (High Resolution Imaging Science Experiment) camera on the MRO, and one of the co-authors of the new study. "We must understand how Mars works today before we can correctly interpret what may have happened when the climate was different, and before we can draw comparisons to Earth."