HiRISE images

A piece of Mars: Sometime in the past, large ripples wandered the dusty lanes of this landscape, sandblasting the hills as they marched on by. Those ripples stopped moving and turned into the fossils you see here. Their bumpy texture indicates that they too are slowly being eroded away. (HiRISE ESP_026462_1740) read more ❯

A piece of Mars: Here is an example of an aeolian enigma. Dunes are depositional, meaning they are made of stuff that piles up on a surface. But these dunes show the strata of the underlying rock within them, which means these things were made from erosion of this rock. So we don't really know how they form, although a few ideas have been kicked around. (HiRISE PSP_008313_1730) read more ❯

A piece of Mars: Dunes near the north pole take on a stretched appearance. It's been proposed that ice in the dunes acts to cement them, which makes them look elongated. (HiRISE PSP_010219_2785) read more ❯

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 ❯

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 ❯

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 ❯

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 ❯

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 ❯

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 ❯

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 ❯