Mysterious ‘almost perfectly circular’ sand dunes have been spotted on Mars by cameras on a NASA spacecraft, leaving scientists scratching their heads.
While sand dunes may be quite common on Mars, it’s surprising that they form almost exact circles, said geologist Alfred McEwen, who examined the photo from NASA’s Mars Reconnaissance Orbiter (MRO).
The shapes were spotted by the HiRISE camera, the most powerful ever sent to another planet on NASA’s MRO, as scientists looked at how ice thaws at the end of the Martian winter.
“Dunes of many shapes and sizes are common on Mars. In this example, the dunes are almost perfectly circular, which is unusual,” wrote McEwen of the University of Arizona, where the HiRISE camera operates.
“They are still slightly asymmetric, with steep landslides at the southern ends. This shows that the sand is generally moving south, but the winds can be variable.
“This is part of a series of images to track how the frost disappears at the end of winter. this observation appears to be free of frost. An earlier image shows when the surface was covered by frost.”
An earlier image shows when the surface was covered by frost.
And last December, the orbiter imaged what looked like a bear’s face on the surface of Mars, leaving people wondering what it could be.
That left HiRISE scientists asking, “A bear on Mars? This feature looks a bit like a bear face. What is true?
“There is a mound with a V-shaped collapse structure (the nose), two craters (the eyes) and a circular fracture pattern (the head).
“The circular fracture pattern could be due to the deposition of a deposit over a buried impact crater. Perhaps the nose is volcanic or mud and the deposit may be lava or mud flows?
The Mars Reconnaissance Orbiter has been in orbit and has been studying Mars since 2006. The spacecraft is designed to study the geology and climate of Mars, provide reconnaissance of future landing sites, and transmit data from surface missions back to Earth.
There was also much discussion last year when a clean-cut “doorway” leading to a rock was seen in a photo of NASA’s Mars taken by the Curiosity rover.
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