Shades and textures

A Piece of Mars: This 480×270 m (0.3×0.17 mi) scene shows the contact between two very different terrains. On the left is a bright surface with polygonal cracks (characteristic of periglacial terrain – this is at a high latitude). On the right is a dark rippled sand sheet that superposes the polygonally-cracked surface. The long

A mighty wind

A piece of Mars: I just adore that the wind can do this to a landscape. Over a long period of time, two different winds have scratched deep grooves in a rocky surface. Wind-carved rocks like this are called “yardangs”. We have them in some deserts on Earth, too, but I’ve never seen two overlapping

Oh, gravity, the things you can do

A piece of Mars: Steep slopes in some parts of Mars are prone to very thin landslides that leave behind dark tracks. The landslides may be triggered by the wind or nearby impacts. They always move downslope — in this case from upper left to lower right, meandering around craters and lapping up against old,

The dunes near Curiosity

A piece of Gale crater, Mars: Here are some of the large, dark dunes not far from where Curiosity has landed. They’re pretty big monsters, 200-300 meters across. Their shape indicates they’ve been formed from two different wind directions: one blowing from the north and one from the ENE. These are the winds that Curiosity

In Curiosity’s channel

A piece of Gale crater, Mars (Aug 11, 2012): This is a tiny portion of the ancient river channel that Curiosity will use to climb up Mt. Sharp in the coming year. It’s a fascinating place, full of pale fractured rocks and partially buried by bluish-gray sand and ripples. (HiRISE ESP_025935_1750)

And the wind blew

A piece of Gale crater, Mars: These are rocks on Mount Sharp, where the Curiosity rover will be headed in the coming months. Like many of the surfaces in Gale crater, these have been streamlined by sandblasting over the eons. (HiRISE PSP_009861_1755)

Patch of blue

A piece of Mars: Most of the image, stretching beyond the edges of this frame, shows a bland gray landscape of lava blanketed in dust. But one small patch of blue shows where sand is still actively moving and piling up. As usual, it’s in the lee of a topographic feature. (HiRISE ESP_027002_1765)

Barely a dune

A piece of Mars: What makes a dune different from a random pile of sand? Usually the requirement is that it has a “slipface”, a steep avalanching slope. The central dune in the image here has a small one, making it a type of dune called a barchan. The other dunes are called “dome dunes”,