Frozen beneath Utopia Planitia, a large plain on Mars, lies about as much water as what’s in Lake Superior, according to an international team of planetary researchers.
This image is an artist’s concept of a view looking down on NASA’s Mars Reconnaissance Orbiter. The spacecraft is pictured using its SHARAD instrument to ‘look’ under the surface of Mars. Image credit: NASA.
Cassie Stuurman, a graduate student at the University of Texas Institute for Geophysics, and her colleagues from the United States and Canada examined part of Utopia Planitia with the ground-penetrating SHARAD (SHAllow RADar) instrument on NASA’s Mars Reconnaissance Orbiter.
Analyses of the data revealed a widespread water ice deposit more extensive in area than the state of New Mexico.
This deposit ranges in thickness from about 260 to 560 feet (80-170 m), with a composition that’s 50 to 85% water ice, mixed with dust or larger rocky particles. It is shielded from the Martian atmosphere by a soil covering estimated to be about 3 to 33 feet (0.9-10 m) thick.
“This deposit probably formed as snowfall accumulating into an ice sheet mixed with dust during a period in Mars history when the planet’s axis was more tilted than it is today,” Stuurman said.
The Utopia deposit represents less than 1% of all known water ice on Mars, but it more than doubles the volume of thick, buried ice sheets known in the northern plains.
“This deposit is probably more accessible than most water ice on Mars, because it is at a relatively low latitude and it lies in a flat, smooth area where landing a spacecraft would be easier than at some of the other areas with buried ice,” said SHARAD co-investigator Dr. Jack Holt, also from the University of Texas Institute for Geophysics.
The Utopian water is all frozen now. If there were a melted layer — which would be significant for the possibility of life on Mars — it would have been evident in the radar scans.
However, some melting can’t be ruled out during different climate conditions when the planet’s axis was more tilted.
This vertically exaggerated view shows scalloped depressions in a part of Mars where such textures prompted researchers to check for buried ice, using the ground-penetrating SHARAD instrument. Image credit: NASA / JPL-Caltech / University of Arizona.
“For many years, planetary researchers have been intrigued by ground-surface patterns there such as polygonal cracking and rimless pits called scalloped depressions — like someone took an ice cream scoop to the ground,” Stuurman said.
“In the Canadian Arctic, similar landforms are indicative of ground ice, but there was an outstanding question as to whether any ice was still present at the Martian Utopia or whether it had been lost over the millions of years since the formation of these polygons and depressions,” added Dr. Gordon Osinski, of the University of Western Ontario in Canada.
The large volume of ice detected with SHARAD advances understanding about Mars’ history and identifies a possible resource for future use.
The results were published online recently in the journal Geophysical Research Letters.
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Cassie Stuurman et al. SHARAD detection and characterization of subsurface water ice deposits in Utopia Planitia, Mars. Geophysical Research Letters, published online September 28, 2016; doi: 10.1002/2016GL070138
