The underside of Antarctica’s dry valleys isn’t so dry after all.
Researchers have discovered extensive saltwater basins more than 100 meters beneath the permafrost, glaciers and frozen lakes that cover one of the McMurdo Dry Valleys. Scientists had previously believed this underground realm was hard, frozen earth. The newly discovered groundwater may have been sealed off for millions of years and could support microbial life, the researchers report online April 28 in Nature Communications.
“From the sky, you see isolated lakes and a polar desert,” says lead author Jill Mikucki, a microbiologist at the University of Tennessee in Knoxville. “But when you look underground, you see a very different story, and that’s what’s so exciting.”The subterranean water hunt was sparked by Taylor Valley’s Blood Falls, where reddish water oozes from between a glacier and a frozen lake. The color in the oxygen-deprived water comes from iron that quickly rusts when it contacts air. This unusual water contains microbes, but scientists didn’t know the water’s source or if liquid water existed anyplace else beneath the dry valleys.
Mikucki and colleagues hung a roughly 25-meter-wide hoop from a helicopter and skimmed over Taylor Valley. An electric current passing through the hoop triggered electric currents in the ground below. Because groundwater more strongly resists currents when frozen, the researchers could distinguish between liquid and frozen water up to 350 meters belowground.
The team detected two groundwater basins beneath the valley that form underground connections between glaciers and frozen lakes previously believed to be isolated. This newfound groundwater is warm enough to support microbial life, and it probably feeds Blood Falls, Mikucki says.
The finding backs the notion that life could exist under Mars’ ice, says microbiologist Brian Lanoil of the University of Alberta in Canada, who was not involved in the study. “These dry valleys are about the closest things we’ve got on Earth to what we see on Mars,” he says.