Vast glaciers of ice are common on Mars, but you have to dig below the surface to find them, new radar views from a NASA spacecraft show.
These hidden deposits of buried Martian ice were first confirmed two years ago, but recent scans of the red planet by NASA's Mars Reconnaissance Orbiter are revealing new clues about how the ice may have gotten there.
Scientists think the Mars glaciers may have been left as remnants when regional ice sheets retreated.
"The hypothesis is the whole area was covered with an ice sheet during a different climate period, and when the climate dried out, these deposits remained only where they had been covered by a layer of debris protecting the ice from the atmosphere," said Jeffrey Plaut of NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The ice extends for hundreds of miles, or kilometers, in a mid-latitude region of Mars called Deuteronilus Mensae.
Plaut and colleagues recently used the spacecraft's Shallow Radar instrument to assemble a map of the Mars ice from more than 250 observations of an area about the size of California.
"We have mapped the whole area with a high density of coverage," Plaut said. "These are not isolated features. In this area, the radar is detecting thick subsurface ice in many locations."
The researchers presented the map at this week's 41st Lunar and Planetary Science Conference near Houston.
Future studies of this buried ice could reveal more about the environmental conditions at the time it was deposited. The glaciers could be a promising target for a future mission to Mars, the scientists said.
The Mars Reconnaissance Orbiter is NASA's most powerful spacecraft currently in orbit around Mars.
The probe launched in 2005 and arrived at the red planet in March 2006. To date, the orbiter has beamed more than 100 terabits of data and photographs to Earth. That's more data on Mars than that collected by all other missions to red planet combined.
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