Artist concept of Glaciers on Mars

This enhanced image shows the inside of a rimless pit about 310 meters (1,017 feet) in diameter, northwest of the mountain Ascraeus Mons in the northern hemisphere of Mars.

NASA's Mars Reconnaissance Orbiter shows bright ripples line the topography in this region, formed within a past climate. Dark dunes and sand streaks, composed of basaltic sand, have moved and fill...

These images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter show how the appearance of dark markings on Martian slope changes with the sea...

The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter caught this view of NASA's Mars Exploration Rover Opportunity on Feb. 14, 2014.

A path resembling a dotted line from the upper left to middle right of this image is the track left by an irregularly shaped, oblong boulder as it tumbled down a slope on Mars before coming to rest...

This map shows the route driven by NASA's Curiosity Mars in its approach to and April 1, 2014, arrival at a waypoint called "the Kimberley," which rover team scientists chose in 2013 as the locatio...

Amazingly, this HiRISE image has captured at least four avalanches, or debris falls, in action.

This image of Victoria Crater in the Meridiani Planum region of Mars was taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter at more of a s...

The upper portion of this map is from an observation by the Context Camera on NASA's Mars Reconnaissance Orbiter of a field of dark sand dunes in the Nili Patera region of Mars.

In the novel and movie "The Martian," an astronaut's adventures take him to the rim of Mawrth Crater. This image from the HiRISE camera on NASA's Mars Reconnaissance Orbiter shows the nature of thi...

These long, smooth features are sand ridges shaped by the constant martian wind. They run perpendicular, or at right angles to, the direction of the wind and often found in channels and crater inte...

This image covers a region of Mars near Nili Fossae that contains some of the best exposures of ancient bedrock on Mars.

Lucus Planum is a part of the enigmatic Medusa Fossae Formation, a broad, soft, and easily eroded deposit. Here this deposit is thin and considerably rougher than elsewhere, implying that it is hea...

This picture of a crater resembling a "happy face" was taken by the Mars Reconnaissance Orbiter's Context Camera. The unnamed crater is almost 2 miles (about 3 kilometers) across That's a BIG smile!

NASA's Curiosity Mars rover can be seen at the "Pahrump Hills" area of Gale Crater in this view from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orb...

These collapse pits probably formed when lava erupted from the side of Arsia Mons, draining underground magma reservoirs. The resulting voids collapse due to the weight of the solid lava above them...

This near-global map was captured by NASA’s Mars Reconnaissance Orbiter using its Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM. The yellow square indicates the Nili Fossae region ...

Sand dunes are among the most widespread wind-formed (aeolian) features present on Mars.

HiRISE image of Planum Chronium Region.

This March 20, 2014, image from the MARCI camera on NASA's Mars Reconnaissance Orbiter has a dark spot (at center of inscribed rectangle) noticed while the image was being examined for a weather re...

This image from NASA's Mars Reconnaissance Orbiter shows an impact crater that triggered a slope streak. When a meteoroid hit the surface and exploded to make the crater, it destabilized the slope ...

This picture of a heart-shaped feature in Arabia Terra on Mars was taken on May 23, 2010, by the Context Camera (CTX) on NASA's Mars Reconnaissance Orbiter.

Shown in this image from NASA's Mars Reconnaissance Orbiter are fan-shaped deposits emerging from regions of steep topography called alluvial fans. Alluvial fans on Mars are thought to be ancient a...

This enhanced-color image shows sand dunes trapped in an impact crater in Noachis Terra, Mars.

NASA's Mars Reconnaissance Orbiter (MRO) keeps finding new impact sites on Mars. This one occurred within the dense secondary crater field of Corinto Crater. The new crater and its ejecta have dist...