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still active, meaning they are still mobile and shaped by the wind, not just old “fossil” (petrified) dunes which are no longer active.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.
In a finding that is sure to fuel the ongoing debate about possible life on Mars, NASA announced yesterday the confirmation that intriguing seasonal dark streaks running down Sun-facing slopes are indeed flows of liquid water. The water is salty (briny), but just the fact that it is current liquid water, albeit transient and in relatively small amounts, is still big news.
Wind-eroded rocks on Mars can take many different forms, sometimes resembling common earthly objects. Some good new examples include these long, thin slivers of rock which look like “spoons” and “needles,” seen by the Curiosity rover recently on sols 1089 and 1087. These fragile formations are easier to form in Mars’ weaker gravity and thinner atmosphere and can last much longer than they would on Earth – a unique form of Martian “artwork.”
The question of how Mars changed from a once wet world to the much colder and drier one we see today is one that scientists have been trying to answer for a long time. There is plenty of evidence that Mars use to have lakes and rivers, and perhaps even oceans. But what happened to change that? Now, a new study might bring us one step closer to solving this conundrum.
After extensive investigations of rock layers in Marias Pass, a shallow valley near the base of Mount Sharp, the Curiosity rover is now heading southwest again, to continue gradually climbing the lower slopes of the mountain. Marias Pass is a region with rocks and ground which contain high levels of silica and hydrogen, more evidence that there used to be a lot more water here than there is now.