HiRISE images

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 ❯

Ripples in a crater
Published 5/20/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Many small craters on Mars are filled, at least in part, by small dunes or ripples. It's one of the distinguishing features of Mars -- a surface marked by geology both old (craters) and young (dunes). This particular crater isn't so old -- boulders surrounding it were made from rocks flung from the impact when it formed, and they are usually one of the first things to erode away as a crater ages. (HiRISE ESP_026726_1790) read more ❯

Dust and oddities
Published 5/17/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: In the dustier regions of Mars, there are many small dark streaks on steep slopes that we don't understand well. Because we don't know much about them we call them "slope streaks", which is not the most imaginative name. They are actively forming on Mars today, though, and seem to be triggered by a disturbance like a nearby earth(mars)quake or a strong wind. Over the next several decades they slowly fade away. (HiRISE ESP_014394_2045) read more ❯

Wind and hills
Published 5/16/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: Blueish and yellowish ripples wind their way around a bright hill. The yellowish ones are probably not moving anymore, but the blueish ones are likely still active from time to time. (HiRISE ESP_020889_1320) read more ❯

Swirls like ribbon ice cream
Published 5/14/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: When the wind erodes layered rocks, it can create a dramatic swirly pattern like this. It looks like ribbon ice cream to me. Mmm, rocks. (HiRISE ESP_011582_1730) read more ❯

One perfect barchan on Mars
Published 5/13/2012 in Lori Fenton's Blog Author lfenton
A piece of Mars: In nature most dunes pile on one another or strongly influence each other. But occasionally, like a perfect flower or crystal, you find a perfectly shaped dune. Here is a crescentic dune, called a "barchan", formed by winds moving from right to left. (HiRISE PSP_007676_1385, NASA/JPL/Univ. of Arizona) read more ❯