Rocks can tell us a lot about a planet. The study of geology has been around on Earth for hundreds of years and has led to scientific discoveries such as the theory of plate tectonics and the discovery of dinosaur fossils. The geology on Mars didn’t last that long and has a long history, but with the rovers landing on the planet in the past few decades, the geology of Mars has started to bloom. Curiosity, one of those rovers, did an especially good job documenting the rock formations near Gale Crater. Now researchers, led by a team at Imperial College London, have published a paper that uses data from Curiosity describing a series of ancient dunes on Mars that provide insight into the planet’s former habitability.
Sand dunes are common on both Earth and Mars. On earth, they are viewed as changing features that literally change with the wind. There is so little environmental activity on Mars that sand dunes are much more stationary and can turn into rock.
Close up of the Stimson Formation in the Murray Buttes with details of the degree of banding.
Photo credit: Imperial College London
This is exactly what happened to a series of sand dunes in Gale Crater, now known as the Stimson Formation. These rocks originally formed as dunes over the rocks deposited in the crater when it was a lake. They then layered in clearly identifiable layers next to Mount Sharp, the highest part of Gale Crater that was not eaten away when it was filled with water.
A noticeable feature of the stratification was that the dunes were apparently caused by winds blowing in two different directions. In particular, they pointed out a feature known as “cross bedding,” where nearby dunes are stacked on top of each other. Usually these are two dunes deposited by competing winds trying to lay sand in different directions.
Detailed top view of the surveyed area of Gale Crater.
Photo credit: NASA / JPL / University of Arizona
These winds were likely to have been well active after the lake bed dried up and the area became much drier. Most likely, the crater would not have been very hospitable during the deposition of the dunes, and the winds that carried abrasive sand might even have scraped away evidence of previous life that existed.
But not all hope of a potentially habitable Gale crater is lost. The frozen dunes form only part of the wall of Mount Sharp, and there are other geological processes that take place further up the mountain. As the researchers continue to comb through the images sent back by Curiosity, they will continue to contribute to the science of geology on Mars. All of this new knowledge will ultimately help answer one of the most asked questions in space exploration – did life ever arise on Mars?
ICL – The changing habitability of Mars as recorded by ancient dune fields in Gale Crater
JGR Planets – A rock record of complex Aeolian bed shapes in a Hesperian desert landscape: The Stimson Formation as exposed in the Murray Buttes, Gale Crater, and Mars
UT – Curiosity finds a region with old dried mud. It could have been an oasis billions of years ago
Part of the Gale Crater that is still being explored by Curiosity
Photo credit: NASA