The surface of Mars

A field of barchan sand dunes appear turquoise blue on the surface of Mars in this enhanced image taken by themore

The base of Mars' Mount Sharp in an image taken by the Curiosity rover. REUTERS/NASA

Dunes on Mars are almost free of their seasonal ice cover during early Martian summer, with pockets of ice stimore

The surface of Mars after a meteoroid hit and exploded, creating an impact crater 5 meters across that triggermore

A view of the Ophir Chasma on the northern portion of the vast Mars canyon system, Vallles Marineris, taken bymore

Nili Patera, one of the most active dune fields on the planet Mars. Image taken by NASA's Mars Reconnaissance more

Rough spherical features in an area called Yellowknife Bay. These features are interpreted as concretions, impmore

An impact crater on Mars is seen in an image taken by NASA's Mars Reconnaissance Orbiter. REUTERS/NASmore

A rock outcrop called Link pops out from a Martian surface. Rounded gravel fragments, or clasts, up to a couplmore

The northern-most sand dunes are seen as they begin to emerge from their winter cover of seasonal carbon dioximore

A location on Mars associated with the best-selling novel and Hollywood movie, "The Martian" This area is in tmore

Portions of the Martian surface showing many channels from 1 meter to 10 meters wide on a scarp in the Hellas more

A view of the Noctis Labyrinthus region of Mars, perched high on the Tharsis rise in the upper reaches of the more

The surface of the planet Mars inside Gale Crater seen from Curiosity. REUTERS/NASA

Curiosity appears as a bluish dot near the lower right corner of this enhanced-color view from Orbiter. REUTmore

Part of the wall of Gale Crater. Here, a network of valleys believed to have formed by water erosion enters Gamore

Inclined layering known as cross-bedding in an outcrop called Shaler on a scale of a few tenths of a meter. more

Two trenches dug by Phoenix's Robotic Arm. REUTERS/NASA/JPL-Caltech/University of Arizona

Mars' Victoria Crater at Meridiani Planum. REUTERS/NASA/JPL/Caltech

An iron meteorite on Mars in an image taken by the Mars Exploration Rover Opportunity. REUTERS/NASA/JPL/Cornmore

This image, cropped from a larger panoramic image mosaic taken by the Mars Exploration Rover Spirit panoramic more