Edited Mars Reconnaissance Orbiter image of layers at the base of a cliff of ice on Mars.

Edited Mars Reconnaissance Orbiter image of Swiss Cheese Terrain in the Martian South Polar Region. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of Roddy Crater.

Edited Mars Reconnaissance Orbiter image of possible jarosite-rich strata in Ius Chasma on Mars. (Jarosite is a sulfate mineral formed by the oxidation of iron (I had to look that up).) Processing variant.

Edited Mars Reconnaissance Orbiter image of megadunes (or is that "mega-dunes"?) in Hyperborei Cavi on Mars.

Edited Mars Reconnaissance Orbiter image of a crater on Mars with a central uplift mountain.

Edited Mars Reconnaissance Orbiter image of slopes of impact craters on Mars. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of a heavily degraded crater (by lava and wind) on Mars.

Edited Mars Reconnaissance Orbiter image of watching gullies for something interesting to happen. (Like flowing water - that would be interesting.)

Edited Mars Reconnaissance Orbiter image of erosion caused by CO2 in rugged terrain.

Edited Mars Reconnaissance Orbiter image of landforms near Aeolis Highlands.

Edited Mars Reconnaissance Orbiter image of a dark part of Mars with dust devil trails. Processing variant.

Edited Mars Reconnaissance Orbiter image of mountains in a field of sand.

Edited Mars Reconnaissance Orbiter image of teardrop defrosting features (presumably shapes) on sand dunes. Martian sand dunes tend to defrost in the oddest shapes...

Edited Mars Reconnaissance Orbiter image of rocky units on a crater floor. ("Rocky units" are, I assume, big chunks of rocks.)

Edited Mars Reconnaissance Orbiter image of a circular crack on the surface of Mars.

Edited Mars Reconnaissance Orbiter image of a recent "candidate" (meaning, "never mind - it's real") impact crater on Mars. Color variant.

Edited Mars Reconnaissance Orbiter image of bedforms that look like petrified sand (or at the least, somehow affixed together) at the bottom of an old crater.

Edited Mars Reconnaissance Orbiter image of possible Pyroxene deposits in Terra Sabaea.

Edited Mars Reconnaissance Orbiter image of a trough on Mars with a strange feature at the bottom. Color/processing variant.

Original caption: This image from NASA's Mars Reconnaissance Orbiter is a close-up of a trough, along with channels draining into the depression. Some HiRISE images show strange-looking formations. Sometimes it helps to look at Context Camera images to understand the circumstances of a scene -- like this cutout from CTX 033783_1509 -- which here shows an impact crater with a central peak, and a collapse depression with concentric troughs just north of that peak.

On the floor of the trough is some grooved material that we typically see in middle latitude regions where there has been glacial flow. These depressions with concentric troughs exist elsewhere on Mars, and their origins remain a matter of debate.

NB: The Context Camera is another instrument onboard MRO, and it has a larger viewing angle than HiRISE, but less resolution capability than our camera.

The map is projected here at a scale of 50 centimeters (19.7 inches) per pixel. [The original image scale is 51.3 centimeters (20.2 inches) per pixel (with 2 x 2 binning); objects on the order of 154 centimeters (60.6 inches) across are resolved.] North is up.

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.

Credit

NASA/JPL-Caltech/Univ. of Arizona

Edited Mars Reconnaissance Orbiter image of the slopes of Nectaris Montes, being monitored for changes. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of a crater on Mars with a central uplift mountain. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of gullies in a crater near Newton Crater on Mars. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of Curiosity next to Namib Dune in Gale Crater. Cropped to show the local region of Curiosity.

Edited Mars Reconnaissance Orbiter image of Gale Crater slopes (but no Curiosity in sight).

Edited Mars Reconnaissance Orbiter image of carbon dioxide frost on sand dunes on Mars. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of dunes in the north polar erg of Mars. Color variant.

Edited Mars Reconnaissance Orbiter image of Barchan sand dunes in the Hellespontus Region. Color variant.

Edited Mars Reconnaissance Orbiter image of a very nicely textured (by wind, probably) surface of Mars with sand dunes on top. Processing variant.

Edited Mars Reconnaissance Orbiter image of a crater 203 meters in diameter in the north polar layer.

Edited Mars Reconnaissance Orbiter image of terrain west of Lasswitz Crater.

Edited Mars Reconnaissance Orbiter image of part of a degraded crater in the Nili Fossae region of Mars.

Edited Mars Reconnaissance Orbiter image of a crater on a snowy plain with snow in the middle and a nice, red ring around the interior.

Edited Mars Reconnaissance Orbiter image of small patches of carbon dioxide snow on sand dunes in the north polar region of Mars. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of slopes of impact craters on Mars.

Edited Mars Reconnaissance Orbiter image of landforms north of Huygens Crater on Mars. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of the residual cap on the south pole of Mars.

Edited Mars Reconnaissance Orbiter image of Gale Crater with Curiosity visible within the image. Grayscale (probably red channel) version.

Edited Mars Reconnaissance Orbiter image of crater slopes on Mars. Color/processing variant.

Edited Mars Reconnaissance Orbiter image of a crater in Meridiani Planum.

Edited Mars Reconnaissance Orbiter image of dark sand dunes on light terrain, or light sand dunes on dark terrain.

Edited Mars Reconnaissance Orbiter PR image of fractured mounds in Elysium Planitia. Processing variant.

Edited Mars Reconnaissance Orbiter image of layers in the wall of Tinto Vallis. Color variant.

Edited Mars Reconnaissance Orbiter image of a pit on Mars.

Edited Mars Reconnaissance Orbiter image of a ridge standing out near the bottom of a crater.

Edited Mars Reconnaissance Orbiter image of Curiosity next to Namib Dune in Gale Crater. Annotated to show location of Curiosity.

Edited Mars Reconnaissance Orbiter image of sublimation on the surface of Mars.

Edited Mars Reconnaissance Orbiter image of the colors at the top of Coprates Chasma on Mars.

Edited Mars Reconnaissance Orbiter image of a Martian crater with persistent ice. Color/processing variant.

Edited Mars Reconnaissance Orbiter</b image of "sustained" bright patches in the Martian north polar region.