March 15, 2007 — Radar scans of Mars have unveiled a vast reservoir of nearly pure frozen water around the planet's south pole, a deposit so rich that if it were spread evenly on the surface it would be 36 feet deep.
Work to map ice deposits on the planet's north pole are under way, but even if they matched the amount found in the south that would still be only a small fraction of the water scientists estimate Mars once had, said planetary scientist Jeff Plaut with NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Using a radar instrument on the European Space Agency's Mars Express orbiter, Plaut and an international team of 23 scientists found layered deposits of ice beneath and beyond a thin cap of frozen carbon dioxide and water at Mars' south pole. The deposits are believed to be at least 90 percent frozen water.
The scientists also found buried depressions in the ice, some as deep as 0.6 miles, that may be old impact craters.
Overall, the ice, which covers an area larger than Texas, is unevenly deposited, with sections as deep as 2.3 miles, the researchers report in this week's issue of the journal Science.
The finding raises questions about why the underlying terrain is so variable in depth. The Mars Express radar data also show streaks of a highly reflective substance, which if the environment were warmer would likely be interpreted as liquid water.
