The ability of NASA's Mars Reconnaissance Orbiter to continue charting the locations of these hidden glaciers and ice-filled valleys -- first confirmed by radar two years ago -- adds clues about how these deposits may have been left as remnants when regional ice sheets retreated.
The subsurface ice deposits extend for hundreds of kilometers, or miles, in the rugged region called Deuteronilus Mensae, about halfway from the equator to the Martian north pole. Jeffrey Plaut of NASA's Jet Propulsion Laboratory, Pasadena, Calif., and colleagues prepared a map of the region's confirmed ice for presentation at this week's 41st Lunar and Planetary Science Conference near Houston.
The Shallow Radar instrument on the orbiter has obtained more than 250 observations of the study area, which is 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 common locations are around the bases of mesas and scarps, and confined within valleys or craters.
Plaut said, "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."
Future Mars outposts or colonies may seem more distant than ever with NASA's exploration plans in flux, but the rocket technology that could someday propel a human mission to the red planet in as little as 40 days may already exist. A company founded by former NASA astronaut Franklin Chang-Diaz has been developing a new rocket engine that draws upon electric power and magnetic fields to channel superheated plasma out the back. That stream of plasma generates steady, efficient thrust that uses low amounts of propellant and builds up speed over time. "People have known for a long time, even back in the '50s, that electric propulsion would be needed for serious exploration of Mars," said Tim Glover, director of development at the Ad Astra Rocket Company.