NASA's Mars Reconnaissance Orbiter has found vast buried Martian glaciers of water ice that extend for dozens of miles from edges of mountains or cliffs. In addition to their scientific value, they could be a source of water to support future exploration of Mars.
Seen here an artist concept of glacier on Mars. Photo Credit: NASA/JPL November 21, 2008, (Sawf News) - NASA's Mars Reconnaissance Orbiter has revealed vast Martian glaciers of water ice buried under a layer of rocky debris at much lower latitudes than any previously identified ice on the Planet.
The glaciers extend for dozens of miles from edges of mountains or cliffs. A layer of rocky debris blanketing the ice may have preserved the underground glaciers as remnants from an ice sheet that covered middle latitudes during a past ice age. The covering has prevented the ice from evaporating.
The findings have similarity to the ice glaciers detected under rocky coverings in Antarctica.
"Altogether, these glaciers almost certainly represent the largest reservoir of water ice on Mars that is not in the polar caps," said John W. Holt of the University of Texas at Austin, who is lead author of the report. "Just one of the features we examined is three times larger than the city of Los Angeles and up to one-half-mile thick. And there are many more. In addition to their scientific value, they could be a source of water to support future exploration of Mars."
This discovery has provided scientists an answer to the Martian puzzle of what are known as aprons - gently sloping areas containing rocky deposits at the bases of taller geographical features - since NASA's Viking orbiters first observed them on the Martian surface in the 1970s.
"These results are the smoking gun pointing to the presence of large amounts of water ice at these latitudes,” said Ali Safaeinili, a shallow-radar instruments team member with NASA's Jet Propulsion Laboratory, Pasadena, Calif.
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The shallow radar instrument for the orbiter, provided by Italian Space Agency, is to examine these mid-latitude geographical features and layered deposits at the Martian poles.
The buried glaciers lie in the Hellas Basin region of Mars' southern hemisphere. The radar also has detected similar-appearing aprons extending from cliffs in the northern hemisphere.
"There's an even larger volume of water ice in the northern deposits,” said JPL geologist Jeffrey J. Plaut, who will be publishing results about these deposits in the American Geophysical Union's Geophysical Research Letters. "The fact these features are in the same latitude bands, about 35 to 60 degrees in both hemispheres, points to a climate-driven mechanism for explaining how they got there."
"A key question is, how did the ice get there in the first place?” said James W. Head of Brown University, Providence, R.I. "The tilt of Mars' spin axis sometimes gets much greater than it is now. Climate modeling tells us ice sheets could cover mid-latitude regions of Mars during those high-tilt periods. The buried glaciers make sense as preserved fragments from an ice age millions of years ago. On Earth, such buried glacial ice in Antarctica preserves the record of traces of ancient organisms and past climate history."
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