Exploring Mars from Earth

Want to poke around on Mars? Since it might be a while before you can actually go there, I suggest you instead make frequent visits to the images page for the HiRise camera on Mars Reconnaissance Orbiter. The pictures that appear here are routinely breath-taking. Below is a cropped image showing the flat top of a mesa in Coprates Chasma. The full image shows detailed layers down the side of the mesa as well as rippled dunes on the mesa top. Everything is remarkably reminescent of something you’d see if you visited the Grand Canyon. Only on Mars, this grand canyon is many times larger and deeper.

Mesa top on Mars

Boulder tracks on Mars

Here’s a nice picture from the HiRISE camera on Mars Reconnaissance Orbiter, released July 7, showing the boulder tracks left by rocks bouncing down the escarpment of Kasei Valles in the low gravity of Mars. Fun quote:

Some of these blocks traveled downhill several hundred meters (yards) as they rolled and bounced, leaving behind a trail of indentations or poke marks in the surface’s fine-grained, light-toned soils. The raised borders in some of these poke marks indicate they are relatively recent features, unaffected by wind erosion, or that this soil has cohesive properties, such as if it was cemented.

Boulder tracks on Mars

Avalanches on Mars

Saturday’s weekly dump of publications from the American Geophysical Union also included a paper that showed visual proof of avalanches on Mars! In this case, the location is Russell Crater, “a large crater in the southern hemisphere that exposes a large dune field in its center.” The avalanches occur because a frost layer made up of dry ice and a little bit of frozen water builds up on the crest of the dunes. When that frost melts, dark streaks about three to six feet wide and about 150 feet long appear, flowing downhill. The scientists believe these are avalanches made up of “a mixing of sand, dust, and unstable CO2 gas.”

wide shot of before and after
Before and after shots of the dark streaks flowing down the dune.

close-up, before and after
Close-ups of the streaks, before and after.

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