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On Mars, the wind wins

ESP_039057_1485_1.0x A piece of Mars: This scene (600×450 m or 1969×1476 ft) is covered in small craters, formed by the splash of a larger crater nearby. They cover everything, even the bright ripples visible on the right. So the ripples were there before the impact that formed all these little craters. And yet… there are itsy little gray ripples on the upper right, merging with the crater rims – these are new ripples, younger than the craters. On Mars, it’s the wind that wins in the end. (HiRISE ESP_039057_1485, NASA/JPL/Univ. of Arizona)

Wind eroded mantle

ESP_039195_1755_0.398xA piece of Mars: The curving ridge of a mountain has signs of many small landslides. Mantled on top of these is an older set of landslides that has been partially eroded away. The rippled edge of this older deposit suggests that it is wind that has done the erosion. So the history here goes: mountains, then landslides, then wind erosion, then new smaller landslides. (HiRISE ESP_039195_1755 NASA/JPL/Univ. of Arizona)

Bearded craters and dunes

ESP_0038826_1700_1.0x
A piece of Mars: This 600×450 m (1969×1476 ft) scene has a complex sedimentary history. How are bearded craters and dunes formed? They weren’t always bearded. At some point, a deposit of bright material accumulated on this surface, and was then eroded so that all that remains of it is what is protected by topography (anything that pokes up like dunes or crater rims). Can you find the boulder that has tumbled downslope (it too has a beard!). (HiRISE ESP_038826_1700, NASA/JPL/Univ. of Arizona)

The long, low dune

ESP_038615_1665_1.0xA piece of Mars: A long, low dune covered in long, linear ripples stretches across the scene (600×450 m; 1969×1476 ft). Dark gray areas on the dune show where sand has most recently moved. A small slip face has formed on the southeast side of the dune, but ripples have formed on it, so there haven’t been any recent avalanches here. (ESP_038615_1665, NASA/JPL/Univ. of Arizona)

Wind, wind, impact(!), and then more wind…

ESP_038918_1650_0.437xA piece of Mars: Some time ago, something hit the ground on Mars and made this impact crater, right into a field of ripples. Stuff thrown up during the impact fell back down, burying the ripples with the gray ejecta rays that radiate from the crater. But the wind kept blowing, and in some places you can see where new ripples have formed on top of the ejecta. That’s Mars for you: wind, wind, wind, impact(!), more wind… (HiRISE ESP_038918_1650, NASA/JPL/Univ. of Arizona)

Aeolian shoreline

ESP_038799_1590_1.0xA piece of Mars: On the left is a steep slope leading to a hill. On the right are waves – but not waves of water or any other kind of liquid. These are dunes or very large ripples, blown by the wind into intricate patterns. Sharp eyes might spy boulders that have rolled downslope into this “sea” – there’s even a dotted track that one boulder made as it went. Can you find the boulder? (HiRISE ESP_038799_1590, NASA/JPL/Univ. of Arizona)

Inverted crater

ESP_038309_1870_0.501xA piece of Mars: This circular hill is 200 m (~656 ft) across and ~48 m (~160 ft) high. It stands alone on a relatively flat plain. Why is it there? The surface here used to be ~48 m higher than it is now – on that old surface, a crater formed. The crater was filled in by sediment. And then the surrounding terrain was eroded away by the wind (that’s a whole lot of stuff to be removed over time!). What’s left is the old crater fill, but one day it too will be blown away. (HiRISE ESP_038309_1870, NASA/JPL/Univ. of Arizona)

MAHLI landscapes

0817MH0003250050301497E01I just… felt like putting up a pretty picture from MAHLI, the microscopic imager on Curiosity. This is image 0817MH0003250050301497E01_DXXX, taken Nov. 23, 2014 (sol 817). The camera mainly takes closeup images of rocks, but it’s also good for a quick landscape shot. You can see where the camera was pointing here.

Panda stripe dustslides

ESP_038387_1855_1.0xA piece of Mars: This 600×450 m (1969×1476 ft) scene of a hillside shows new, dark dustslides that slid downhill (to the lower left). Faint stripes of older dustslides are visible, covered by bright dust and small ripples. Thousands of these form every year on Mars, stretching several kilometers downslope – there is nothing quite like this here on Earth! (HiRISE ESP_038387_1855, NASA/JPL/Univ. of Arizona)

Textured gullies

ESP_038389_1105_0.501xA piece of Mars. These are gullies on a martian hillside (upslope is to the upper right). Water may be what forms the channels, carrying soil and rocks downslope. The textured pattern of the lower slope is caused by the wind forming ripples on loose sediment that has been transported partway down the hill. (HiRISE ESP_038389_1105, NASA/JPL/Univ. of Arizona)