The discovery of life in extreme ecosystems beneath the ice sheets covering Antarctica raises the tantalizing possibility that similar severe environments in our solar system could harbor some kind of life, scientists say.
That's the thought offered by researchers who've retrieved samples of healthy bacteria and other microorganism living in a freshwater lake buried beneath a half mile of ice on the frigid continent.
The environment in Lake Whillans might not be all that different from environments on a number of the icy moons of Saturn and Jupiter, they say.
Europa, a moon of Jupiter, and Enceladus, orbiting Saturn, both have been found to possess large amounts of liquid water lying beneath their icy crusts.
Drilling down into the depths of Lake Whillans, scientists were surprised to find almost 4,000 microbial species living in the dark water, many of them dining on inorganic compounds as their primary energy source.
"People weren't really thinking about ecosystems underneath the ice," says biologist Brent Christner of Louisiana State University. "The conventional wisdom was that they don't exist, it's a place that's too extreme for this kind of thing."
It's the extreme nature of the environment in the coldest place on Earth that has scientists thinking of the possibilities of life existing elsewhere in our solar system.
There are almost 400 similar lakes trapped deep beneath the permanent ice cover of Antarctica, with a number of them -- including Lake Whillans -- connected by subterranean streams and rivers.
Those waterways regularly fill and drain Lake Whillans like a giant bathtub in a cycle lasting between five to 10 years.
The lake has been completely entombed in ice for at least a million years, the researchers say.
In a $10 million project funded by the National Science Foundation, the researchers broke through the covering ice of the West Antarctic Ice Sheet into Lake Whillans in 2013 using a special heated-water drilling system equipped with a decontamination system designed to ensure any samples brought up for the lake's waters were pure and not contaminated with surface organisms.
After the successful drilling project, the scientists returned to the U.S. and their laboratories with around 8 gallons of lake water and a number of sediment cores drilled from the lake's bottom.
A number of institutions were involved in culturing the sample single-cell organisms and sequencing their DNA.
"We were surprised about the number of organisms," Christner says. "It's really not that different than the number of organisms in a lake on the surface."
The exciting part of the discovery is that the ecosystem of Lake Whillans is probably the closest found on Earth so far to possible environments on distant moons or planets, the researchers said.
"I think this does strengthen the case for finding life on icy bodies," Christner says.
