DENVER--Glaciers may be hiding on Mars beneath piles of rocks that had been identified as a kind of landslide. If these common features of the martian landscape really are glaciers in disguise, they could contain a historical record of the planet's climate and clues to the future of Earth's climate.
Long piles of rock, stretching several kilometers, can be seen on the sides of many martian hills and mountains. The most popular interpretation has been that these are jumbles of mud and rock called debris flows. Some geologists, however, have suggested that they are masses of ice and rock that creep downhill. On Earth, these so-called rock glaciers develop regularly spaced ridges as the ice crumples at the bottom where the slope flattens out.
Richard Marston and Christopher Neel of Oklahoma State University in Stillwater noticed that some of the so-called debris flows on Mars had similar sets of ridges. So Neel sized up four rock glaciers in Colorado and compared them to one of the martian debris flows imaged by NASA's Mars Odyssey orbiter. A statistical analysis revealed that the ridge spacing is very similar on the two planets. Earlier this year, the Mars Odyssey spacecraft also revealed the presence of near-surface ice (ScienceNOW, 28 May), making glaciers seem even more plausible, Marston says. The team presented their results here this week at the annual meeting of the Geological Society of America.
"I think this type of approach is the way to determine what these are," says Bruce Jakosky, a planetary geologist from the University of Colorado, Boulder. Confirming that the features are glaciers will require another visit to the red planet, but if they do turn out to be glaciers, they could reveal aspects of past and present climate on Mars, such as whether a large ocean ever existed, he says. Some scientists have speculated that Earth is following Mars down the same climatic path, says team member John Degenhardt of Texas A&M University in College Station, so martian glaciers might provide a preview for Earth's future climate.
And if humans ever try to visit or colonize Mars, a readily available source of water could be critical. "The glaciers might be the most accessible sources of water," says Degenhardt. The water could potentially be converted to hydrogen fuel for a return trip to Earth as well, he says.