These might look like trees on Mars, but they're not. Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. The image was taken near the North Pole of Mars, spring 2010. Objects about 25 centimetres across are resolved on this image, which is about one kilometre wide. Close ups of some parts of this image show billowing plumes indicating that the sand slides were occurring at the time of the photo; see center left.
The "Mystery of Mars' Dunes" refers to the puzzling sight of dunes on the surface of Mars that do not behave as expected based on our understanding of dune formation on Earth.
The dunes on Mars are different from dunes on Earth in several ways. They are much larger, with some reaching heights of up to 500 feet. They also have different shapes and patterns, with some appearing to be in a star shape. Additionally, the dunes on Mars are made of different materials, such as basaltic sand and dust, whereas Earth's dunes are typically composed of quartz and other minerals.
These dunes are a mystery because they do not behave as expected based on our current understanding of dune formation. On Earth, dunes are formed by wind blowing sand and other particles, but the atmosphere on Mars is much thinner and the wind speeds are not strong enough to create and sustain the large dunes that we see. This raises questions about how these dunes were formed and what other factors may be at play.
There are several theories about the formation of these dunes. One theory is that they were formed by ancient winds that were stronger and more frequent on Mars. Another theory suggests that the dunes were formed by the movement of frozen carbon dioxide, or dry ice, on the surface. Some scientists also believe that the dunes may be the result of a combination of different processes.
Scientists are studying these dunes through various methods, including using images and data collected by orbiting spacecraft and rovers on the surface of Mars. They are also conducting experiments and simulations to better understand the conditions and processes that may have led to the formation of these dunes. Additionally, future missions, such as the Mars 2020 rover, will continue to gather data and provide more insights into this intriguing mystery.