Mars is often referred to as a desert world, being bone-dry for the most part, with dust and sand blanketing most of the surface. Some regions are covered in vast sand dunes, reminiscent of deserts like the Sahara on Earth, only much colder. Gale crater, where the Curiosity rover landed in 2012, features extensive dune fields around the base of Mount Sharp, and the rover is now approaching some of them for the first time; their dark color makes them stand out starkly against the surrounding terrain. These dunes are also still active, meaning they are still mobile and shaped by the wind, not just old “fossil” (petrified) dunes which are no longer active.
Phobos is the largest of Mars’ two tiny moons, but 50 million years from now, that may no longer be the case. According to new research, Phobos is gradually being pulled apart by Mars’ gravity and will eventually be destroyed. The unusual long grooves on Phobos’ surface, which have been a puzzle for planetary scientists, are a key piece of evidence that point to eventual structural failure of this little worldlet.
The various rover and lander missions on Mars have provided unprecedented glimpses into the planet’s past, including geological history and environmental conditions. In many ways, ancient Mars was similar to Earth, with abundant water and volcanic activity. Now, new research has revealed that there was also another related Earth-like phenomenon: acid fog.
Last week there was the exciting news that Mars still has flows of briny water occurring now, and this week there is more water-related news: additional findings from the Curiosity rover that the huge Gale crater was once a lake or series of lakes a long time ago. Curiosity had already found evidence that there used to be shallow lakes and streams in this area, but the new data confirms this and suggests that the lake(s) once filled Gale crater and were long-lasting, explaining the formation of Mount Sharp in the middle of the crater and also providing a potentially habitable environment for life.
Another beautiful panoramic image of the foothills of Mount Sharp, taken by Curiosity on Sep. 9, 2015. The mesas, buttes and valleys can be seen in greater detail as the rover keeps getting closer. The image has been white-balanced to show the terrain under more Earth-like lighting conditions. The full-size version of the image is available here.