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The bright Antarctic reflection on Mars could be clay instead of water

The South Pole of Mars looks like a creamy whirlpool of cappuccino, but is an icy cap with carbon dioxide and other geological features. About a mile below the cap is smectite, a hydrated version of clay. Credit: ESA / Mars Express

The bright reflections observed in the South Pole of Mars serve as evidence of water. But seeing may be fooling.


After measuring the area Electrical properties Orbit and penetrate the ground radarAccording to a July 29 report in the journal, an international group of scientists said that the Antarctic reflection of the red planet could be smectite, a type of hydrated clay buried about a mile below the surface. It states that there is. Geophysics Research Letter..

Isaac B from York University in Toronto. The study, led by Smith and contributed significantly by second author Dan Lalich, a researcher at Cornell University’s Center for Astrophysics and Planetary Sciences in the Faculty of Arts and Sciences, said it was necessary for the presence of liquid water. .. Incredible amount of heat and salt.

“These bright reflections were initially interpreted as liquid water under ice, which has been a big news in the last few years,” says Lalich. “That interpretation contradicts other observations, which means that the ice is not warm enough to melt, given what we know about the state of Mars.”

Even on Earth, we rarely see underground reflections from radar that are brighter than surface reflections, Lalich said.

The reflex is about a mile below the surface of the planet, “I don’t think it’s as bright as the reflex,” he said. “We were getting radar cross sections that were much brighter than the surface, and that’s really weird. It wasn’t what we actually saw before, and it wasn’t what we expected.”

The group scrutinized data from MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) equipment, a radar that inspects the underground of Mars with a 130-foot antenna via the European Space Agency’s Mars Express orbiter. The MARSIS instrument, jointly developed by the Italian Space Agency and NASA’s Jet Propulsion Laboratory, can explore planets to a depth of three miles.

Lalich and other scientists used the diagnostic physical characteristics of ground penetrating radar, called permittivity, to measure the ability to store electrical energy.Group used Reflection Strength to estimate the difference in permittivity between ice and the bottom of the polar cap. The estimates were then compared to smectite laboratory measurements.

“Mars is very rich in smectites, especially in the Southern Hemisphere, which covers about half of the Earth,” said Smith at the University of York. “That knowledge, along with the radar characteristics of smectites at very low temperatures, shows that they are the most likely explanations of the mystery.”

Lalich said the data for identifying hydrated clay can be easily reproduced from the observed data. That is, no liquid water is needed to produce bright reflections. Scientists wanted to find lakes and other geological forms.

“Unfortunately, it was a little depressed,” he said. “The lake under the ice cap would have been very exciting. We believe that the smectite hypothesis is more likely and more consistent with other observations.”

In addition to Smith and Larich, the co-author of “A Solid Interpretation of Bright Radar Reflectors Under the Antarctic Ice on Mars” is Craig Lezza, a graduate student at the University of York. Briony Hogan, Associate Professor at Purdue University. Jennifer L. Witten, Associate Professor at Tulane University. Postdoctoral fellow Stefano Nerozzi and University of Arizona professor Jack Holt.


Research sheds new light on composition at the base of Mars’ Antarctic crown


For more information:
IB Smith et al, a solid interpretation of bright radar reflectors under Martian Antarctic ice, Geophysics Research Letter (2021). DOI: 10.1029 / 2021GL093618

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Cornell University

Quote: The bright Antarctic reflex on Mars can be clay. Obtained from https://phys.org/news/2021-07-mars-bright-south-pole-claynot.html on July 29, 2021, not water (July 29, 2021).

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The bright Antarctic reflection on Mars could be clay instead of water

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