Misled by a Mars Mirage: Hope for Present-Day Martian Groundwater Dries Up
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Misled by a Mars Mirage: Hope for Present-Day Martian Groundwater Dries Up:
Liquid water previously detected under Mars' ice-covered south pole is probably just a dusty mirage, according to a new study of the red planet led by researchers at The University of Texas at Austin.
Scientists in 2018 had thought they were looking at liquid water when they saw bright radar reflections under the polar cap. However, the new study published today (January 24, 2022) in the journal Geophysical Research Letters found that the reflections matched those of volcanic plains found all over the red planet's surface.
The researchers think their conclusion - volcanic rock buried under ice - is a more plausible explanation for the 2018 discovery, which was already in question after scientists calculated the unlikely conditions needed to keep water in a liquid state at Mars' cold, arid south pole.
"For water to be sustained this close to the surface, you need both a very salty environment and a strong, locally generated heat source, but that doesn't match what we know of this region," said the study's lead author, Cyril Grima, a planetary scientist at the University of Texas Institute for Geophysics (UTIG).
The south polar mirage dissolved when Grima added an imaginary global ice sheet across a radar map of Mars. The imaginary ice showed how Mars' terrains would appear when looked at through a mile of ice, allowing scientists to compare features across the entire planet with those under the polar cap.
Grima noticed bright reflections, just like those seen in the south pole but scattered across all latitudes. In as many as could be confirmed, they matched the location of volcanic plains.
Journal Reference:
C. Grima, J. Mouginot, W. Kofman, et al. The Basal Detectability of an IceCovered Mars by MARSIS, Geophysical Research Letters (DOI: 10.1029/2021GL096518)
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