A self-portrait of the Mars rover Curiosity.
Photograph by NASA, Ap
This field of dunes lies on the floor of an old crater in Noachis Terra, one of the oldest places on Mars.
Photograph by NASA, JPL, University of Arizona
This enhanced colour image shows several craters somewhere in the southern mid-latitudes of Mars. The bluish deposits are most likely iron-bearing minerals that have not been previously oxidised, or rusted.
Photograph by NASA, JPL, University of Arizona
The impact site of the heat shield from NASA's Mars Exploration Rover Opportunity.
Photograph by NASA, JPL, Cornell
Sand dunes are among the most widespread aeolian, or wind-blown, features on Mars. These areas provide clues to the sedimentary history of the surrounding terrain.
Photograph by NASA, JPL Cal-tech, University of Arizona
Groups of dark brown streaks were photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost.
Photograph by Hirise, NASA
The panoramic camera on NASA's Mars Exploration Rover Opportunity captured this scene of the west rim of Endeavour Crater during the summer of 2014.
Photograph by NASA, JPL, Hirise
Sand dunes litter the floor of Aram Chaos, an eroded impact crater east of Mars' Valles Marineris canyon range.
Photograph by NASA Jpl-caltech, University of Arizona
Melas Chasma is the widest segment of Valles Marineris, the largest canyon in the solar system.
Photograph by NASA, JPL, University of Arizona
The Opportunity rover spent four months perched on the northern slope of Greely Haven and snapped more than 800 images of its surroundings.
Photograph by NASA
Russell Crater dunes are a favourite target for the Mars Reconnaissance Orbiter's HiRISE camera, not only because of their incredible beauty, but for measuring the accumulation of frost each autumn and its disappearance in the spring.
Photograph by NASA
The holes visible in this image are not impact craters, but rather material that was ejected from a large crater called Hale that does not appear in here. Explosions formed moats, which have been partially covered over time by sand dunes (top).
Photograph by Hirise, Jpl, NASA
NASA's Curiosity rover snapped this 360-degree panorama as part of a long-term campaign to document the context and details of the geology and landforms along Curiosity's traverse since landing in 2012.
Photograph by Jpl, NASA
Recurring slope linae (RSL) are seasonal flows on warm slopes, and are especially common in central and eastern Valles Marineris.
Photograph by Jpl, NASA
Victoria Crater has a distinctive 'scalloped' shape to its rim, caused by erosion and downhill movement of crater wall material.
Photograph by Hirise, NASA
Dust accumulation on a rover's solar panels reduces its power supply, and the rover's mobility is limited until winter is over or wind cleans the panels.
Photograph by NASA
The Curiosity rover captured the Bagnold Dunes inside Gale Crater on Sept. 25, 2015.
Photograph by NASA
Partially exposed bedrock is revealed within the Koval'sky impact basin.
Photograph by Hirise, Jpl, NASA
This dramatic, fresh impact crater spans approximately 30 metres in diameter and is surrounded by a large, rayed blast zone.
Photograph by NASA
The north polar layered deposits are layers of dusty ice up to three kilometres (two miles) thick and approximately 1,000 kilometres (620 miles) in diameter.
Photograph by NASA
Sand dunes are among the most widespread wind-formed features on Mars. Their distribution and shapes are affected by changes in wind direction and wind strength.
Photograph by NASA
This selfie from NASA's Curiosity rover shows the vehicle at the site from which it reached down to drill into a rock target called 'Buckskin' on lower Mount Sharp.
Photograph by NASA
Researchers used the Curiosity rover in March 2015 to examine the structure and composition of the criss-crossing veins at the 'Garden City' site in the centre of this scene.
Photograph by NASA
This crater near Sirenum Fossae has steep inner slopes carved by gullies.
Photograph by NASA
This image covers many shallow irregular pits with raised rims, but researchers aren't sure how these odd features formed.
Photograph by NASA
At this site in the lower mounter in Gale Crater, orbiting instruments have detected signatures of both clay minerals and sulphate salts. This change in mineralogy may reflect a change in the ancient environment in Gale Crater.
Photograph by NASA
Viscous, lobate flow features are commonly found at the bases of slopes in the mid-latitudes of Mars, and are often associated with gullies.
Photograph by NASA
Many Martian landscapes contain features that are familiar to ones we find in Earth, like river valleys, cliffs, glaciers and volcanoes.
Photograph by NASA
Two of the raised treads, called grousers, on the left middle wheel of NASA's Curiosity rover broke during the first quarter of 2017, including the one seen partially detached at the top of the wheel in this image from the camera on the rover's arm.
Photograph by NASA
In the scenic 'Murray Buttes' area, individual buttes and mesas were assigned numbers. This one is referred to as 'M9a'.
Photograph by NASA
This observation from NASA's Mars Reconnaissance Orbiter shows late summer in Mars' southern hemisphere. The sun is low in the sky, highlighting the subtle topography.
Photograph by NASA
NASA's Curiosity rover team has assessed the small bright object just below the centre of this image and believes it is debris from the spacecraft.
Photograph by NASA
The 'High Dune', which is part of the 'Bagnold Dunes', was the first Martian sand dune ever studied up close. The dunes are active, migrating up to about one yard or metre per year.
Photograph by NASA
A towering dust devil casts a serpentine shadow over the Martian surface in this stunning, late springtime image of Amazonis Planitia.
Photograph by NASA
Landforms called 'gullies' found on many large Martian sand dunes consist of an alcove, channel, and apron.
Photograph by NASA
NASA plans to launch a rover to Mars in 2020.
Photograph by NASA
