HOUSTON—Researchers using radar data from NASA’s Mars Reconnaissance Orbiter have observed a subsurface ice deposit on the Red Planet that rivals the size of Lake Superior, the largest of the U.S. Great Lakes.
It is located beneath Utopia Planitia, an ancient impact crater basin in Mars’ mid-northern latitudes.
More extensive in area than New Mexico, the buried ice deposit ranges from 260 ft. to 560 ft. thick and is comprised of 50 to 85% water ice mixed with rocky particles and dust, according to data gathered from more than 600 overhead passes by MRO, which launched and entered orbit around Mars in 2005-06.
The ice deposit is covered by layers of Martian soil ranging from 3 to 33 ft. thick.
The find, using MRO’s Shallow Radar instrument, could serve as a resource for future human explorers as well as scientists pursuing the time scales and circumstances for a change in the global Martian environment from warm, wet and possibly suitable for microbial life to one that is cold and dry with a thin atmosphere composed primarily of carbon dioxide.
The findings, published in Geophysical Research Letters (GRL), suggest the deposit originated as snowfall during an earlier era when Mars was tilted off its rotational axis to a greater extreme than the current 25 deg., according to Cassie Stuurman, a researcher from the University of Texas Institute for Geophysics who led the study.
“This deposit is probably more accessible than most water ice on Mars because it is at a relatively low latitude and it lies in a flat, smooth area where landing a spacecraft would be easier than at some of the other areas with buried ice,” according to fellow University of Texas researcher and co-author Jack Holt in a joint statement with Stuurman. It was issued Nov. 22 by the university and NASA’s Jet Propulsion Laboratory.
Last year NASA’s Human Exploration and Operations and Science directorates initiated an ongoing effort called the Human Landing Sites Study initiative. It was established to identify candidate landing zones for future human explorers on the Red Planet that would be within range of in situ resources, as well as regions of scientific value to address whether Mars hosts or once hosted biological activity and when and why it underwent environmental change.
“Where water ice has been around for a long time, we just don’t know whether there could have been enough liquid water at some point for supporting microbial life,” Holt said of the Planitia Utopia subsurface ice deposit, which stretches from 39 deg. to 49 deg. north latitude.
Scientists from the University of Arizona’s Lunar and Planetary Laboratory described a similar discovery last year in GRL. It was a subsurface ice deposit estimated to be the combined size of California and Texas and about 130 ft. thick. It was also in the mid-latitudes of the Martian northern hemisphere in a region known as Arcadia Planitia.
Utopia Planitia, site of the recent discovery, covers a region just more than 2,000 mi. in diameter created by an impact with another Solar System object early in Mars’ history.
In 1976, NASA’s Viking 2 mission lander settled onto the center of the basin, just northeast of the site studied by Stuurman and her science colleagues.
“The ice deposits in Utopia Planitia aren’t just an exploration resource,” stresses University of Texas researcher and co-author Joe Levy. “They’re also one of the most accessible climate change records on Mars.
We don’t understand fully why ice has built up in some areas of the Martian surface and not in others. Sampling and using this ice with a future mission could help keep astronauts alive, while also helping them unlock the secrets of Martian ice ages.”