Found: ‘Spirit of the Dunes” on Mars
How ‘Ghost Dunes’ could reveal past life on the Red Planet.
Newly published research shows that hundreds of depressions on the Mars surface, known as “ghost dunes,” could hold evidence of ancient life.
The research, published in the Journal of Geophysical Research: Planets, shows that each of the old dunes (probably dunes), the size of the U. S. Capitol. They have remained preserved for years as a result of the way they were built, with lava and sediment, partially buried by the dunes in time, allowing them to become desensitized, the research states.
“We know that the dunes on the Earth can live, and the dunes and on the Earth are very similar to the dunes on Mars. A problem Mars has that Earth is not the surface radiation,” said Mackenzie Day, a planetary geomorphologist at the University of Washington and lead author of the study in a statement to the American Geophysical Union. “If you’re in a dune, or the bottom of a dune, and the microbial life, the dune is to protect you from a lot of radiation.”
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Barchan dunes march across a plain in the Hellespontus region, west of Hellas basin, Mars. The orientation of their horns provides consistent winds from the east blowing top to bottom in this picture taken by the Mars Reconnaissance Orbiter. Sun lights up the steep slopes of the leeward, or downwind, faces, on the dunes’ the bottom. The dunes migrate with the wind, sometimes merging or extending long fingers, which spawn new dunes. (Credit: NASA/JPL/University of Arizona)
The plain language summary of the research gives more details about what researchers can expect from the dunes.
“These pits can contain the old dune sandstone around the edges of the pits and a good place to search for evidence of ancient life,” the summary reads. “The shapes of the pits also tell us how the wind behaved in the past.”
The dunes were identified thanks to satellite images of the Hellas basin, and the Noctis Labyrinthus on the Red Planet.
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The horns of barchan dunes indicate the prevailing wind from the north (top), in Egypt, in the Western Desert close to Kharga (25.706⁰, 30.347⁰).
(Credit: Google Earth)
Precedent in the universe
There is precedent for this phenomenon on Earth, as a so-called “ghost dunes” were found on the Snake River Plain in eastern Idaho in 2016.
It is very likely that the dunes at Noctis stood close to 130 feet high, which, in the Hellas basin, towered higher still, coming in at about 246 feet, before the wind and Mars’ ancient climate buried. Known as barchan dunes, these dunes (which are the most common on both Earth and Mars) “half-moon-shaped” and form on flat surfaces, “unhindered by the vegetation, when the wind is blowing mainly from one direction and sand is limited.”
Day and her co-author David Catling, an astrobiologist at the University of Washington, noted that this “spirit dunes are similar in size and scope of the active dune fields on the Red Planet, making it probably the pits are indeed sand dunes.
“One of these pits is not enough to tell you that it is a dune, or an old dune area,” Day added. “But if you put them all together, they have so much in common with dunes on Mars and on Earth, and that you have to employ a kind of fantastic explanations to explain them as something other than the dunes.”
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Day and Catling estimate that the dunes were buried approximately 2 billion years ago, during the Hesperian period, or Amazon period. The Hesperian period is important, researchers say, because that is when the planet’s climate changed from a wet environment, “with running water and active volcanoes,” on the dry and the wind swept climate currently seen on the planet.
It is unclear why the climate changed, but Space.com reports that the atmosphere thinned out, which would make it impossible for the water to flow.
“The fact that the wind was different [as the ghost in the dunes formed] tells us that the environmental conditions on Mars are not static over long periods of time, they have changed in the past few billion years, something we have to know the interpretation of the geology on Mars,” Day added in the statement.
Day pointed out on the opportunities of the life in the spirit dunes at distance, but it can provide insights into the planet the first day and help researchers understand how big has formed.
“There is probably nothing living there now,” Day said. “But if ever there was something on Mars, this is a better spot than the average to watch.”
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