Geoboffins spot hundreds of ghost dunes on Mars

Mars was once covered in hundreds of giant dunes as big as the US Capitol Building billions of years ago, according to new research.

A pair of scientists from the University of Washington have discovered more than 300 crescent-shaped structures wedged into the eastern side of Hellas Planitia, an impact crater measuring over 2,700 kilometers (1,678 miles).

They studied satellite images and found pits also known as “ghost dunes”. Flowing liquid or lava partially swamped the dunes, where they hardened over time. Winds wore away the exposed tips and emptied them from the inside out, leaving the empty husks behind.

“They are all going the same way, which you would expect for dunes because they are all migrating and forming in the same wind regime. So just the shape and size tell us that these are features that are coming from an ancient dune system," said Mackenzie Day, first author of the paper published in the Journal of Geophysical Research Planets.

It is estimated that the average size of dune stood about 40 meters (130 feet) high at Noctis Labyrinthus, a region of Mars known for the deep patterns carved from channels of lava. At Hellas basin, an impact basin, the dunes were probably larger at about 75 meters tall.

It’s an exciting find as it provides more evidence to support the idea that Mars may have harbored life at one point.

"We know that dunes on Earth can support life, and dunes on Earth are very similar to dunes on Mars. One problem that Mars has that Earth doesn't is the surface radiation. If you are inside a dune, or at the bottom of a dune, and you are microbial life, the dune is protecting you from a lot of that radiation," Day said. "There is probably nothing living there now. But if there ever was anything on Mars, this is a better place than average to look." ®