Water-ice clouds, polar ice, polar regions, and geological features can be seen in this full-disk image of Mars. (NASA/JPL)
Thousands of point elevation measurements from the laser altimeter onboard the Mars Global Surveyor spacecraft were processed to create this computer-generated view of the largest volcano yet known in our solar system, Olympus Mons. This volcano stands more than 90,000 feet above its base, and yet its flank slopes are only about six degrees, similar to that of its cousin volcano Mauna Loa in Hawaii. (NASA/MOLA Science Team/ O. de Goursac, Adrian Lark.)
Within a 150-km diameter crater named Proctor, in the southern highlands on Mars, is this dark dune field. The reason these dunes are so dark is because they are composed of basaltic sand that has collected at the bottom of the crater. Between the dark dunes and on the crater floor are many smaller and brighter formations. (NASA/JPL-Caltech/University of Arizona)
Chasma Boreale is a long, flat-floored valley that cuts deep into Mars' north polar icecap. Its walls rise about 1,400 meters (4,600 feet) above the floor. Where the edge of the ice cap has retreated, sheets of sand are emerging that accumulated during earlier ice-free climatic cycles. Winds blowing off the ice have pushed loose sand into dunes and driven them down-canyon in a westward direction, toward our viewpoint. (NASA/JPL-Caltech/ASU)
Mars Reconnaissance Orbiter's (MRO) HiRISE instrument has transformed our view of Mars from a barren world to one of diverse and active landscapes. (NASA/JPL-Caltech/University of Arizona)
This computer-generated view depicts part of Mars at the boundary between darkness and daylight, with an area including Gale Crater beginning to catch morning light. (NASA/JPL-Caltech)
NASA's Mars Exploration Rover Opportunity is spending the seventh anniversary of its landing on Mars investigating a crater called "Santa Maria," which has a diameter about the length of a football field. (NASA/JPL-Caltech/Cornell/ASU)
In the Gordii Dorsum region of Mars there is a large area covered with polygonal ridges in an almost geometric pattern. The ridges may have originally been dunes that hardened through the action of an unknown process. It is possible that groundwater may have been involved in that process. (NASA/JPL-Caltech/University of Arizona)
A towering dust devil, casts a serpentine shadow over the Martian surface in this image acquired by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. (NASA/JPL-Caltech/Univ. of Arizona)
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 sideways angle than earlier orbital images of this crater. (NASA/JPL-caltech/University of Arizona)
Looking a bit like chocolate mountains with forests of chocolate pine trees, these are in fact dunes from the southern hemisphere on Mars during the winter-time. The brighter tones are thought to be carbon dioxide or water frost. (NASA/JPL-Caltech/University of Arizona)
This view shows color variations in bright layered deposits on a plateau near Juventae Chasma in the Valles Marineris region of Mars. A brown mantle covers portions of the bright deposits. The view covers an area about 1.2 kilometers (three-fourths of a mile) across. (NASA/JPL-Caltech/University of Arizona)
ESA's Mars Express obtained this perspective view of an unnamed impact crater located on Vastitas Borealis, a broad plain that covers much of Mars's far northern latitudes. The coordinates are about 70.5 degrees North and 103 degrees East. (ESA/DLR/FU Berlin (G. Neukum))
View of the north polar region of Mars from orbit. The ice-rich polar cap (quasi-circular white area at center) is about 1,000 km across. It is bisected by a large canyon, Chasma Boreale, on the right side. Dark, spiral-shaped bands are troughs. Chasma Boreale is about the length of the Grand Canyon in the U.S. and up to 2-km deep. (NASA/Caltech/JPL/E. DeJong/J. Craig/M. Stetson)
The High Resolution Imaging Science Experiment (HiRISE) camera would make a great backyard telescope for viewing Mars, and we can also use it at Mars to view other planets. This is an image of Earth and the moon, acquired on October 3, 2007, by the HiRISE camera on NASA's Mars Reconnaissance Orbiter. (NASA/JPL-Caltech/University of Arizona)
This view Gale crater shows the mound of layered rocks that NASA's Mars Science Laboratory will investigate. The mission's selected landing site is just north of the mound inside the crater. (NASA/JPL-Caltech/MSSS/Tanya Harrison)
Dunes of sand-sized materials have been trapped on the floors of many Martian craters. This is one example, from a crater in Noachis Terra, west of the giant Hellas impact basin. (NASA/JPL-Caltech/University of Arizona)
This mosaic of images taken in mid-January 2012 shows the windswept vista northward (left) to northeastward (right) from the location where NASA's Mars Exploration Rover Opportunity is spending its fifth Martian winter, an outcrop informally named "Greeley Haven." (NASA/JPL-Caltech/Cornell/Arizona State Univ.)
NASA's Mars Exploration Rover Spirit captured this stunning view as the sun sank below the rim of Gusev crater on Mars. (NASA/JPL/Texas A&M/Cornell)
This image from NASA's Phoenix Mars Lander's Optical Microscope shows a strongly magnetic surface which has scavenged particles from within the microscope enclosure before a sample delivery from the lander's Robotic Arm. The particles correspond to the larger grains seen in fine orange material that makes up most of the soil at the Phoenix site. They vary in color, but are of similar size, about one-tenth of a millimeter. (NASA/JPL-Caltech/University of Arizona/Imperial College London)
This view from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter shows two classes of aeolian bedforms within Proctor Crater. The relatively bright, small ridges are ripples. (NASA/JPL-Caltech/University of Arizona)
Mars' seasonal cap of carbon dioxide ice has eroded many beautiful terrains as it sublimates (goes directly from ice to vapor) every spring. In the region where the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter took this image, we see troughs that form a starburst pattern. (NASA/JPL-Caltech/University of Arizona)
West of Valles Marineris lies a checkerboard named Noctis Labyrinthus, which formed when the Martian crust stretched and fractured. As faults opened, they released subsurface ice and water, causing the ground to collapse. (NASA/JPL-Caltech/ASU)