Scientists have discovered the remains of a recent glacier near Mars’ equator, raising the prospect that ice may still exist in the area at shallow depths.
The discovery of ice on Mars could have important ramifications for future human exploration of the Red Planet, but scientists emphasised at the 54th Lunar and Planetary Science Conference in Texas that it is “a salt deposit” with “glacier-like structures,” not ice.
The surface feature known as a “relict glacier” is one of several light-toned deposits (LTDs) found in the area. LTDs are often made up of light coloured sulphate salts, however this deposit also has many of the characteristics of a glacier, including as crevasse fields and moraine bands.
The glacier is believed to be 6 km long and up to 4 km wide, with a surface elevation ranging from 1.3 to 1.7 km. This finding shows that Mars’ recent history was more wet than previously thought, which could have consequences for comprehending the planet’s habitability.
“What we’ve found is not ice, but a salt deposit with the detailed morphologic features of a glacier. 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 crevasse fields and moraine bands,” said lead author Dr. Pascal Lee, a planetary scientist with the SETI Institute and the Mars Institute.
The fine-scale characteristics of the glacier, its related sulphate salts deposit, and the overlying volcanic materials are all very sparsely cratered by impacts and must be geologically young, most likely Amazonian in age, the most recent geologic epoch that includes current Mars.
“We’ve known about glacial activity on Mars at many locations, including near the equator in the more distant past. And we’ve known about recent glacial activity on Mars, but so far, only at higher latitudes. A relatively young relict glacier in this location tells us that Mars experienced surface ice in recent times, even near the equator, which is new,” said Lee.
It needs to be observed whether water ice is still there beneath the light-toned coating or if it has vanished completely.
“Water ice is, at present, not stable at the very surface of Mars near the equator at these elevations. So, it’s not surprising that we’re not detecting any water ice at the surface. It is possible that all the glacier’s water ice has sublimated away by now. But there’s also a chance that some of it might still be protected at shallow depth under the sulphate salts,” Lee noted.