Dune Sea of Mars' Ganges Chasma
The Mars Reconnaissance Orbiter captured this image over the eastern edge of Mars' Ganges Chasma.

NASA/JPL-Caltech/University of Arizona

Troughs in Mars' Elysium Fossae
The Mars Reconnaissance Orbiter captured this image over troughs in Mars' Elysium Fossae

NASA/JPL-Caltech/University of Arizona

Self Portrait of Mars Rover Curiosity
This self-portrait of the Curiosity rover shows the vehicle at a drilled sample site called "Okoruso".

NASA/JPL-Caltech/MSSS

Mars' Memnonia Fossae
This Mars Express image shows Mars' Memnonia Fossae.

ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Mars' Marathon Valley
Taken by the Mars Exploration Rover Opportunity, this image reveals a panoramic view of Marathon Valley.

NASA/JPL-Caltech/Cornell University/ASU

Mars' Chasma Boreale
This image is a simulated 3-D perspective view of Mars' Chasma Boreale.

NASA/JPL/ASU, R. Luk

Colorful Deposits on Mars
Mars Reconnaissance Orbiter image of colorful polar layers on Mars.

NASA/JPL-Caltech/University of Arizona

Mars' Hellas Basin Rim
Perspective view of Mars' Hellas Basin generated from the high-resolution stereo camera on the Mars Express spacecraft.

ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Dust Devil on Mars
Captured by the Mars Exploration Rover Opportunity, this image reveals a dust devil twisting through a martian valley.

NASA/JPL-Caltech

Lakebed on Mars
This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA's Curiosity Mars Rover shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake.

NASA/JPL-Caltech/MSSS

Pillinger Point, Mars
This scene from the panoramic camera (Pancam) of NASA's Mars Exploration Rover Opportunity catches "Pillinger Point," on the western rim of Endeavour Crater, in the foreground.

NASA/JPL-Caltech/Cornell/ASU

TARs on Mars
This HiRISE image shows a valley filled with an assortment of linear ridges. These ridges are often referred to as transverse aeolian ridges, or TAR, and they take a variety of forms.

NASA/JPL/University of Arizona

Barchan Dunes on Mars
The Mars Reconnaissance Orbiter's high-resolution imager HiRISE captured this false-color image of barchan sand dunes.

NASA/JPL-Caltech/University of Arizona

Linear Gullies on Mars
This image from the HiRISE camera on NASA's Mars Reconnaissance Orbiter reveals linear gullies.

NASA/JPL-Caltech/Arizona State University

First Sample Drilling on Mars
Hole drilled by NASA's Curiosity rover as its first sample drilling. The rock is called "John Klein."

NASA/JPL-Caltech/MSSS

Mars' Matijevic Hill
Panoramic photo mosaic taken by NASA's Mars Exploration Rover Opportunity.

NASA/JPL-Caltech/Cornell/ASU

Mars Landing Site Panorama
Panoramic image mosaic of the Martian landing site of NASA's Curiosity rover.

NASA/JPL-Caltech/MSSS

Ancient Streambed on Mars
NASA's Curiosity rover finds evidence of an ancient streambed on Mars at "Hottah" outcrop.

NASA/JPL-Caltech/MSSS

Layered Rock on Mars
A chapter of the layered geological history of Mars is laid bare in this postcard from NASA's Curiosity rover. The image shows the base of Mount Sharp, the rover's eventual science destination.

NASA/JPL-Caltech/MSSS

Mars' Mount Sharp
This image taken by NASA's Curiosity rover shows what lies ahead for the rover -- its main science target, Mount Sharp.

NASA/JPL-Caltech