Mars Thermal Readings Show Ice Layers at Various Depths

NASA's OPRA warthog robot will have to dig for ice under the soil with a robotic "shovel," but new infrared images will tell him exactly how deep he has to dig to find it.

The new thermal images show underground ice depth can vary significantly on the Mars, being right at the surface in one spot but several feet down nearby, according to the composition on the soil directly above the ice.

The instrument used to obtain the thermal images is called THEMIS, (Thermal Emission Imaging System), and it's part of NASA's Mars Odyssey orbiter.

"We find the top layer of soil has a huge effect on the water ice in the ground," said study author Joshua Bandfield of Arizona State University.

The new Phoenix mission will also benefit from the new data, as it too has been designed to drill down to sample Martian soil and ice.

It seems that the composition of the soil directly affects the depth at which frozen water can form. Areas with many rocks at the surface "pump a lot of heat into the ground and increase the depth where you'll find stable ice," Bandfield explained. On the other hand, dusty areas form an insulating layer that allows ice to get closer to the surface.

"These two surface materials - rock and dust - vary widely across the ground, giving underground ice a patchy distribution," Bandfield said.

Previous observations made astronomers theorize that Martian ice was located at average depths of about 3 to 6 feet (1 to 2 meters), but Bandfield's new study shows it can be found as close as 2 inches (5 centimeters) from the surface and it can take pictures that have about 5,000 times higher resolution than those taken by another Mars Odyssey instrument, the Gamma Ray Spectrometer.

Another use for the new images is in the choice of Phoenix's landing spot, now set to launch later this year.