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Martian ice deposit contains as much water as Lake Superior

Martian water ice deposit.

Martian ice deposit. This vertically exaggerated view shows scalloped depressions in a part of Mars where such textures prompted researchers to check for buried ice, using ground-penetrating radar aboard NASA’s Mars Reconnaissance Orbiter. Image & Caption Credit: NASA/JPL-Caltech/Univ. of Arizona

Scientists using data from NASA’s Mars Reconnaissance Orbiter (MRO) have discovered a layer of water ice beneath a region of cracked and pitted plains on Mars that holds about as much water as what is in Lake Superior, largest of the Great Lakes.

Researchers examined part of Mars’ Utopia Planitia region using MRO’s ground-penetrating Shallow Radar (SHARAD) instrument. Analysis of data from more than 600 passes using the spacecraft’s radar instrument shows a deposit larger in area than the state of New Mexico. This deposit varies in thickness from about 260 feet (80 meters) to about 560 feet (170 meters) and is composed of 50 to 85 percent water ice, mixed with dust or large rocky particles.

In the mid-northern latitudes of Mars where this deposit is located, about halfway from the equator to the pole, water ice cannot persist on the surface of Mars – it sublimes into the water vapor in the planet’s thin dry atmosphere. The Utopia Planitia deposit is shielded from the atmosphere by a soil covering estimated to be from about 3 to 33 feet (1 to 10 meters) 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,” said Cassie Stuurman of the Institute for Geophysics at the University of Texas, Austin. She is the lead author of a report in the journal Geophysical Research Letters.

Mars today has an axial tilt of 25 degrees and accumulates large amounts of water ice at the poles. In cycles lasting nearly 120,000 years, the tilt varies to nearly twice that much, heating the poles and shifting ice to lower latitudes. Climate modeling and the discovery of previously buried ice deposits indicate that water ice accumulates away from the poles during high-tilt periods.

The newly discovered ice deposit spans latitudes from 39 to 49 degrees within the Utopia Planitia region. While the deposit represents less than one percent of known water ice on Mars, it more than doubles the volume of thick, buried ice sheets known in the northern plains. Ice deposits close to the surface could be a vital resource for future human exploration of the Red Planet.

“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 Jack Holt of the University of Texas, a co-author of the Utopia paper who is a SHARAD co-investigator and has previously used radar to study Martian ice in buried glaciers and the polar caps.

Utopia Planitia on Mars

Diagonal striping on this map of a portion of Mars’ Utopia Planitia region indicates the area where a large subsurface deposit rich in water ice was assessed using the Shallow Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter. Image & Caption Credit: NASA/JPL-Caltech/Univ. of Rome/ASI/PSI



Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.

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