WASHINGTON, Nov 20: NASA scientists have discovered enormous underground reservoirs of frozen water on Mars, away from its polar caps, in the latest sign that life might be sustainable on the Red planet.

Ground-penetrating radar used by the Mars Reconnaissance Orbiter reveals numerous huge glaciers up to one half-mile thick buried beneath layers of rock and debris. Researchers said one glacier is three time the size of Los Angeles in area.

“All together, these glaciers almost certainly represent the largest reservoir of water ice on Mars that's not in the polar caps,” said John Holt, a geophysicist at the University of Texas at Austin and lead author of a report about the discovery, which appears in the Nov 21 issue of the journal Science.

“In addition to their scientific value, they could be a source of water to support future exploration of Mars,” said Holt.

Scientists on the 12-member research team surmise that the frozen water deposits are remnants of a Martian ice age millions of years ago.

Because water is one of the primary requirements for life, scientists said the frozen reservoirs are an encouraging sign of extra-terrestrial life.

The buried glaciers reported by Holt and his 11 co-authors lie in the Hellas Basin region of Mars' southern hemisphere, and scientist said even larger frozen water reservoirs may exist in Mars' northern hemisphere.

“The fact that 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,” said Holt.

Another member of the research team noted however, that a basic mystery about the glaciers remains unsolved. “A key question is 'How did the ice get there in the first place?'” said James Head of Brown University.

Unanswered questions also persist, Brown said, about what might be contained in the frozen water.

“On Earth, such buried glacial ice in Antarctica preserves the record of traces of ancient organisms and past climate history,” he said.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA.—AFP