HiRISE images

Boulder tracks
Published 6/4/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: You can't easily tell here, but you're looking at a steep slope that is high at the bottom of the image and flattens out at the top of the image (the small dunes at the top sit at the foot of the wall). What's neat here are the many small boulder tracks, formed as rocks get knocked down. A road through this canyon would need a sign saying "Warning Falling Rocks". (HiRISE ESP_026356_1960) read more ❯

Active wind erosion
Published 6/3/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Bright rocks are being scoured and shaped by dark (bluish) sand. On Mars, active geologic activity is easy to identify: when there aren't many craters visible, you're probably looking at a surface that is undergoing change. This is a good example of such a surface. (HiRISE ESP_016000_1670) read more ❯

Festoons of geology past
Published 5/31/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Erosion by sandblasting has revealed layers in volcanic rock. Likely nearly horizontal, the wind here has shaped the surface so the layers appear to be festoons, swirling across the landscape. (HiRISE ESP_021627_1975) read more ❯

Swirls and stripes
Published 5/30/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: I know, I keep showing ripples. But they're all so different. This one has a distinct swirl appearance, like it's stretched and twisted taffy. The complexities of the winds that create these things are not at all understood. (HiRISE PSP_003101_1320) read more ❯

Visited wind streaks
Published 5/29/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Back in 2007, the Mars Exploration Rover Opportunity spent a great deal of time investigating the rim of Victoria crater. Here is the northern rim of the crater, showing three dark (bluish) sandy streaks formed by the wind as it blows dark sand out of the crater. You can see small dark ripples inside the crater, the source of the dark sand. And if you look very carefully you can see the tracks the rover left behind. (HiRISE PSP_009141_1780) read more ❯

Complex winds
Published 5/28/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: My brain keeps seeing it as stuffed pillows, but it's the other way around -- the sun is coming from the upper left, so the centers of the little polygons are low and their edges are sharp-crested dunes. Or maybe ripples, we're still not sure. Stare at it until your brain makes it work that way. The little ripples inside them were formed after the big ones. I can tell because their orientation is so strongly affected by the topography of the big ones. (HiRISE ESP_026599_1500) read more ❯

Tuning forks of the wind.
Published 5/27/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Small, dark ripples have overridden larger, bright ones. The larger ones have some interesting shapes -- arcs, splits that resemble tuning forks, and even circles. Their shape is accentuated by the smaller, very regular ripples between them. (HiRISE PSP_004077_1325). read more ❯

Fashionable stripes of Mars
Published 5/24/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Is it the latest in patterns for ties, or is it Mars? (Can it be both?) These are some unusually regular dunes on Mars, separated by a bouldered surface. The dunes have interesting pale bands common in this region on Mars, as well as an unending supply of long, parallel ripples. (HiRISE ESP_025108_1370) read more ❯

At the edge
Published 5/23/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Old, subdued dunes (in blue) near the south pole on Mars. This shows the edge of a dune field, with white rock-strewn surface beyond the sand. Criss-crossing the sand are the tracks that dust devils have left behind. I wonder if these whirlwinds are the main reason why the dunes are slowly eroding to a flat surface. (HiRISE PSP_005980_1085) read more ❯

When dunes die
Published 5/22/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: This is what dunes look like when they die. At least on Mars. On Earth they typically get buried or eroded away. On Mars geology works slowly enough that the steep slopes of dunes are gradually reworked and pitted, and covered in fine layers of bright dust. (HiRISE PSP_005980_1085) read more ❯

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