For the first time, scientists have discovered lands on the Earth’s surface that appear to harbor no life at all. The soils came from 2 windswept, rocky ridges in the interior of Antarctica, 300 miles from the South Pole, where hills poke through ice that is thousands of feet thick.

“The assumption has always been that germs are tough, they can reside anywhere,” states Noah Fierer, a microbial ecologist at the University of Colorado, Boulder, whose staff studied the lands. Single-celled organisms consumed, after all, been discovered living in hydrothermal vents around 200 degrees Fahrenheit, alive in lakes trapped beneath half a mile of ice in Antarctica, as well as surviving 120,000 feet upward from the Earth’s stratosphere. But after a year of trying, Fierer and his PhD student Nicholas Dragone have not found any signs of life in a number of the Antarctic lands they gathered.

Fierer and Dragone studied lands from 11 different mountains, representing a broad range of conditions. Those from the lower, less frigid mountains comprised bacteria and fungi; however in some of those from the two highest, driest, and coldest mountains, no signs of life stirred.

“We can’t say they are sterile,” says Fierer. Microbiologists are utilized to finding millions of cells at a teaspoon of soil; so a minuscule number–say, 100 living cellscould potentially escape detection. “But as much as we can tell, they do not harbor any parasitic life.”

Whether some of those lands are truly lifeless, or later turn out to harbor a few surviving cells, then this new discovery–recently published in the diary JGR Biogeosciences–could help guide efforts to find life on Mars. The Antarctic lands are perpetually frozen, saturated in poisonous salts, and haven’t tasted appreciable amounts of liquid water for up to two million years–similar to Martian soils.

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They had been collected during a January 2018 expedition, financed by the U.S. National Science Foundation, to some remote section of the Transantarctic Mountains. Those cut via the continent’s inside, separating the high polar plateau at the east from the low-lying ice of the west. Scientists camped on Shackleton Glacier, a 60-mile-long conveyor belt of ice that spills down through a gap in the hills. They used a helicopter to get to the peaks and collect samples up and down the glacier.