New images released from the Mars satellite reveal glimpses of the planet's complex past that has turned arid and dusty.
From high above the Martian surface, the orbiting High Resolution Imaging Experiment (HiRISE) is in Danielson Crater, just north of the Martian equator. This region is of great interest to space geologists because of the layers of sediment that line the craters.
Layered deposits can be found all over Mars, but Danielson Crater contains some of the most spectacular and best-preserved. Even more interesting, these areas appear to be equally spaced with different levels of erosion: the stronger layers form the steps, with the softer layers of material inside.
Quoted from Science Alert, the flatness of these layers means they cannot be created by random processes, such as impact events. Instead, scientists think that an orderly and iterative process deposited the layers.
"The rock was formed millions or billions of years ago when loose sediment settled in the crater, one layer at a time, and then cemented in place," NASA wrote in a blog post.
"The cyclical variation in sediment properties makes some layers more resistant to erosion than others. After thousands of years, these harder layers protrude like steps. Across these steps, the wind spreads the sand (usually it appears darker and less red, i.e. 'bluer' in contrast-enhanced colors), giving rise to a zebra stripe-like pattern."
On a small scale, there are large areas of rock that are heavily fractured. Scientists have studied these fractures and determined that because the pieces fit together perfectly, this occurred after the sediment had turned to rock. It's not clear exactly how these deposits were formed, but they could be made over a span of years, or even longer.
Some scientists have suggested that the periodic process could be the result of climate change associated with variations in the orbit of Mars. Other studies suggest that groundwater upwelling may be responsible for this formation.
There are so many amazing Martian rocks that planetary geologists want to see firsthand. Meanwhile, orbiters with extraordinary cameras, such as HiRISE, are helping to uncover Mars' fascinating history.