Using data from the High Resolution Imaging Science Experiment (HiRISE) on NASA’s Mars Reconnaissance Orbiter (MRO), researchers from the SETI Institute and the Mars Institute discovered light-toned deposits (LTDs) on the surface of Mars. These features consist of bright sulphate salts, fissure fields and moraine bands, which are indicative of a “relict glacier”.This relict glacier is located near the Martian equator at 7° 33′ S, 93° 14′ W, and is estimated to be 3.7 miles (6 kilometers) long and up to 2.5 miles (4 km) wide, with a surface height reaching up to 1.1 miles (1.7 km), according to a declaration (opens in new tab) from the SETI Institute.
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“What we have found is not ice, but a salt deposit with the detailed morphological features of a glacier,” Pascal Lee, lead author of the study and a planetary scientist at the SETI and Mars Institutes, said in the statement. “What we think happened here is that salt formed on top of a glacier while preserving the shape of the ice below, down to details like fissure fields and moraine bands.”
The presence of such a glacier suggests that there may have been surface water ice on it Mars more recent than previously thought, which has implications for both our understanding of the red planet’s habitability and future exploration missions.
“This region of Mars has a history of volcanic activity. And where some of the volcanic material came into contact with glacial ice, chemical reactions would have occurred at the boundary between the two to form a hardened layer of sulfate salts,” Sourabh Shubham, study co-author and graduate student in the University of Maryland’s Department of Geology, said in the statement, “This is the most likely explanation for the hydrated and hydroxylated sulfates we observe in this light-toned deposit.”
The observed LTDs consist of sulfate salts formed when freshly erupted pyroclastic materials—volcanic ash, pumice, and hot lava—come into contact with water ice. As these deposits build up, they form a hardened, crusty layer of salt. Over time, erosion would have exposed the salt deposits along with fissures and moraine bands that are unique to glaciers.
“Glaciers often present distinctive types of features, including marginal, extended fissure fields and tic-tac-toe fissure fields, and also thrust moraine bands and sheets,” John Schutt, co-author of the study and a geologist at the Mars Institute, said in the statement. “We see analogous features in this bright deposit in shape, location and scale. It’s very exciting.”
Previous research has found glacial activity near the Martian equator in the more distant past, whereas recent glacial activity has only been seen at higher latitudes until now. The recent HiRISE observations suggest that these low-latitude LTDs are geologically young, according to the statement.
“A relatively young relict glacier at this site tells us that Mars has experienced surface ice in recent times, even near the equator, which is new,” Lee said in the statement.
Although water ice is not stable at the surface of Mars near the equator at these altitudes, it is possible that some of the glacial water ice may be preserved beneath the sulfate salts. Further research is needed to confirm, but if water ice is indeed present in this equatorial region, there is the possibility that it could be mined as a resource for future missions.
“The desire to land people in a place where they might be able to do that extract water ice from Earth has pushed mission planners to consider locations at higher latitudes. But the latter environments are typically colder and more challenging for humans and robots. If there were equatorial locations where ice could be found at shallow depth, then we would have the best of both environments: warmer conditions for human exploration and still access to ice,” Lee said in the statement. “We must now determine whether , and how much water ice is actually present in this relict glacier, and whether other light-toned deposits may also have or have had ice-rich substrates.”
The results were submitted (opens in new tab) at the 54th Lunar and Planetary Science Conference held in The Woodlands, Texas, on March 15.
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