The Mars rovers may get most of the glory and attention, but they're not the only Earth visitors currently in residence at the Red Planet.
NASA's Mars Reconnaissance Orbiter has been in orbit since 2006, looking down and sending back images and data to mission control.
A photo from the orbiter shows a fascinating view of a Mars sand dune curling around the surface and looking like a giant leech. "These images provide information about eosion and movement of surface material, about wind and weather patterns, even about the soil grains and grain sizes," NASA notes.
The sand dune may be the star of the picture, but scientists are learning a lot by looking at the area around it. Researchers noticed a "resistant and highly fractured surface" around the dune and believe it could be shattered bedrock that is not prone to erosion. Another possible explanation is that the area consists of dried mud cracks.
The image was taken by the spacecraft on July 30, but just released Wednesday as a NASA Image of the Day.
The Mars Reconnaissance Orbiter played a big role in the recent NASA announcement confirming the presence of. Images taken by the spacecraft were key to the discovery.
The orbiter launched back in 2005 and has been taking high-resolution photos of the landscape ever since its arrival at its new home. It gives researchers plenty to puzzle over as they work to sort out the planet's geologic make-up and the processes that form dramatic landscape features like the dunes and fractures.