Saturday , September 18 2021

The bright reflections observed at the southern pole of Mars may be clayey rather than watery

Two years ago, planetary scientists reported the discovery of a large saltwater lake beneath the ice at the south pole of Mars. In 202, scientists confirmed the presence of underground lakes. The discovery of the lakes of Mars deep under the ice cap at the south pole of Mars was made using a radar instrument in the orbit of the Mars Express ESA (European Space Agency).

Scientists have measured the electrical properties of the area using radar orbiting the Earth. Based on the data, they claim that the reflections of the south pole of the red planet could be smectite, a form of hydrated clay, buried about a kilometer below the surface.

The research, led by Isaac B. Smith of York University in Toronto, with significant contributions from another author, Dan Lalich, a research associate at the Cornell Center for Astrophysics and Planetary Science at the College of Arts and Sciences.

Scientists said “The presence of running water requires incredible amounts of heat and salt.”

Lalich said, “These great reflections have been big news for the last few years because they were initially interpreted as running water under ice. This interpretation is inconsistent with other observations indicating that the ice is not warm enough to melt, given what we know about conditions on Mars. ”

“The reflection is about a mile and a half below the south polar subterranean surface of Mar, where you don’t expect such a great reflection. We were getting radar reflections that were much brighter than the surface. And that’s weird. It’s not something we’ve seen before, nor expected. ”

The group studied data from MARSIS instruments. They then used a diagnostic physical property in ground-penetrating radar called dielectric transmittance, which measures the ability to store electricity. Scientists were then able, using the power of reflection, to estimate the difference in permeability between the ice and the base of the polar cap.

They then compared these estimates with laboratory smectite measurements.

Smith of York University said, “Smectites are very numerous on Mars, covering about half of the planets, especially in the southern hemisphere. This knowledge, along with the radar properties of smectites at cryogenic temperatures, suggests that they are the most likely explanation for the puzzle. “

Lalich said, “The data to confirm the hydrated clay are easily reproduced from the observed data, which means that running water is not needed to create brilliant reflections. Scientists hoped to find lakes and other geological forms. ”

“Unfortunately, it’s a bit bad because the lakes under the ice cap would be very exciting. We believe that the smectite hypothesis is more plausible and more consistent with other observations. ”

Other co-authors of the study are Craig Rezza, a graduate student, York University; Briony Horgan, Associate Professor, Purdue University; Jennifer L. Whitten, Assistant Professor, University of Tulane; and Stefano Nerozzi, postdoctoral research associate, and Jack Holt, professor, University of Arizona.

Journal reference:
  1. IB Smith et al. A solid interpretation of the bright radar reflectors beneath Mars’ southern polar ice. DOI: 10.1029 / 2021GL093618

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