NASA scientists have developed a map detailing the presence of water ice on Mars, with some believed to be as little as 2.5 centimetres below the Red Planet's surface. The researchers, including those from the American space agency's Jet Propulsion Laboratory (JPL) in California, said in a press statement that water ice will be a key consideration for any potential landing site on Mars.
They added that with little room to spare aboard a spacecraft, any human missions to Mars may have to harvest what is already available there for drinking water, and for making rocket fuel.
In the current study, published in the journal Geophysical Research Letters, the scientists used data from two satellites orbiting the Red Planet -- NASA's Mars Reconnaissance Orbiter (MRO), and Mars Odyssey orbiter -- to locate water ice that could potentially be within reach of astronauts.
"You wouldn't need a backhoe to dig up this ice. You could use a shovel," said study lead author, Sylvain Piqueux from JPL.
"We're continuing to collect data on buried ice on Mars, zeroing in on the best places for astronauts to land," Piqueux said.
The regions noted in the study are near the Martian poles, and have been studied by NASA's Phoenix lander, which scraped up ice, and by the MRO, which has taken many images from its orbit of meteor impacts that have excavated this ice.
To find the ice deposits, the scientists used two heat-sensitive instruments -- the MRO's Mars Climate Sounder, and the Thermal Emission Imaging System (THEMIS) camera on Mars Odyssey.
They said, the buried water ice changed the temperature of the Martian surface.
So the researchers cross-referenced temperatures suggestive of ice with other data, such as reservoirs of ice detected by radar, or seen after meteor impacts.
They also used data from Odyssey's Gamma Ray Spectrometer, which they said is tailor-made for mapping water ice deposits.
Based on their analysis, the researchers said a trove of water ice is present throughout the Martian poles and mid-latitudes.
The new map particularly shows shallow deposits of water ice that future mission planners may want to study further.