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You have already heard about the blue dunes on Mars, Inquisitr but what are the "ghost dunes"?
Well, as you probably know now, the surface of the red planet is punctuated by sand dunes. Some of them are newer, more modern, as are the dunes of barchan (crescent shaped) found in the craters of Oyama and Herschel; others are ancient and date back billions of years, when Mars still had flowing water and active volcanoes.
In the ancient past of the planet, some of these dunes were covered with lava, which hardened into a kind of a cast that enclosed ancient material in the sand dunes. Later, when the winds swept the top of the dunes, they carried off the upper layers of sand, leaving behind the empty casts that are now preserved as pits in the Martian surface.
Because they are hollow remains of ancient sand dunes, these empty pits or shells have been dubbed "ghost dunes", and the researchers have recently located about 800 of them, found grouped in two distinct regions on the red planet, reports Science Magazine . was made by planetary geomorphologist Mackenzie Day and astrobiologist David Catling, both affiliated with the University of Washington at Seattle and the Institute of Astrobiology at NASA California.
Scientists discover ghost dunes on #March https: / /t.co/OZBCQw3x8R
– Phys.org (@physorg_com) July 11, 2018
C & # 39 is the first time that ghost dune pits have been discovered on Mars, reveals a new study, published by Day and Catling in the Journal of Geophysical Research .
These new geological features were discovered by satellite images and are grouped into two dune fields erected in very distinct areas on Mars. About 480 of these pits were discovered at Noctis Labyrinthus, a region similar to a labyrinth of steep canyons and valleys, while another 300 dune ghosts were detected in the Planitia Hellas, an impact crater of more than 2 500 km. By comparing ghost dunes with the modern sand dunes of Oyama and Herschel craters, the two researchers were able to calculate their age, size and age.
According to GeoSpace the blog of the American Geophysical Union, the ghost dunes recently discovered on Mars appear to have been formed about two billion years ago at the end of the year. Hesperian, a tumultuous and transient period The history of the planet is characterized by extensive volcanic activity and a catastrophic flood.
In inspiring the discovery, Day noted that all the common features of these sand pits indicate an ancient dune system preserved by a partial burial.
"No matter which of these pits is not enough to tell you that it's a dune, or an old dune field, but when you put them all together, they have so much of points in common with the dunes on Mars and on Earth that you have to use some kind of fantastic explanation to explain them other than as dunes. "
The two researchers estimate that the ghost dunes of Noctis Labyrinthus were about 40 meters (130 feet) high when they were buried the lava flows, while those in the Hellas Basin were almost twice as high. At a height of 75 meters (246 feet), these sand dunes are almost the size of the US Capitol Building, note Atlas Obscura .
Another peculiarity of the ghost dunes is that they are all crescent-shaped (they look like croissants) and are oriented in the same direction, molded by winds from the north and gently pushing the sand towards the south – something that is not seen on Mars today.
about ghost dunes, that is, they tell us, for sure, that the wind on Mars was different in the past, when they formed, "said Day
In Perspective on the History of Mars [19659003] This shows that the environmental conditions on Mars do not stay static for long periods and have in fact changed a lot over the past two billion years – a very important revelation for the study of Martian geology.
relevant is because ghost dune pits can actually be dubbed with ancient dune sandstones, which could have encapsulated traces of microbial life past.
"The possibility for wind strata to be preserved in pits at an interface formerly hot or rich in water makes the pits of interest for astrobiology" wrote in their journal .
Last Science Magazine news: "Ghost dunes & # 39; spotted on Mars https://t.co/WWtVtqHfZK
– ScienceSeeker Feed (@SciSeekFeed) 11 July 2018
"We know that dunes on Earth can support life," said Day, pointing out that sand dunes on Mars are very similar to those found at home.
In fact, ghost dunes also occur on Earth. for the first time in 2016. Discoveries on the plain of the Snake River in eastern Idaho, these ghost dunes date back to the Upper Pleistocene, reports Atlas Obscura .
Whether on Earth or Mars, the flow of water could have deposited traces of microbial life at the bottom of these ancient sand dunes. And, in the case of the red planet, the dunes would have sheltered from the intense surface radiation, thus increasing the chances that they may still show some signs of extraterrestrial life from the past, Day says.
"There is probably nothing left alive here, but if there is anything on Mars, it's a better place than the average to look at."
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