Antarctic microbes have astrobiologists looking to Europa

Posted by Eric Betz
on Wednesday, August 27, 2014

The WISSARD team cultured bacterial colonies from Lake Whillans water column samples. // Image courtesy Louisiana State University
There’s life half a mile beneath the icy surface of Antarctica. And that has astrobiologists talking about the possibilities for life on other planets.

In a study published last week in the journal Nature, researchers say they’ve found what might be the first hints of a massive microbial ecosystem buried beneath as much as 5 million square miles (13 million square kilometers) of ice sheet.

Scientists analyzed samples collected from the subglacial Lake Whillans and found a diverse community of microbes. The organisms aren’t just surviving there; they are thriving in a robust ecosystem far from sunlight. According to the paper, the newly found life pulls energy from rocks and sources its carbon from C02.

“Before we drilled into this place and sampled it, we weren’t sure that we were going to find these active ecosystems,” said Brent Christner, lead scientist on the Whillans Ice Stream Subglacial Access Research Drilling project, or WISSARD.

In a press release issued by the National Science Foundation, John Priscu of Montana State University, Bozeman referred to the subglacial habitat as Earth’s largest wetland. Hundreds of other lakes, rivers, and streams are thought to exist beneath the ice of our planet’s southernmost continent.

The discovery has major implications for the possibilities of life on other worlds, including some in our own solar system. Jupiter’s icy moon Europa as well as Saturn’s Enceladus both have oceans and are geologically active, leading to speculations that they could be home to extraterrestrial life.

“This is easily one of the most exciting ecosystems on Earth,” said Kevin Hand, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California.

Similar to Antarctica, the surface of a place like Europa would have sunlight available for photosynthesis, but it would be far too cold for life to thrive. The greater chance to find life is in the substantially warmer oceans far below the ice, which could be as much as 100 km thick.

And as the WISSARD team showed, drilling to those depths and successfully sampling an alien sea will be no small challenge.

Members of the Antarctic team were heavily scrutinized in the 1990s after finding microbes in Lake Vostok, providing indirect evidence for what was happening on the bottom of the ice sheet. After that experience, they spent years just trying to find a way to drill half a mile without contaminating the lake – which had been cutoff from the surface for a million years – or their sample. Ultimately, the Antarctic researchers accessed the pristine environment last summer by drilling with clean, hot water.

“What we did was extremely difficult. If you’re going to do this in an extraterrestrial environment, it’s that level of difficulty times 100,000,” Christner said. “We received some scrutiny. I can’t imagine the level of scrutiny when someone discovers a life form from some place other than Earth. It may be the most scrutinized discovery of all time.”

Drilling with hot water also won’t be possible on a place like Europa. Instead, plans are being drawn up to use nuclear power and melt through the ice, while keeping contact with the surface through a fiber-optic cable.

Hand is helping plan NASA’s potential mid-2020s trip to the icy world, and he still thinks that the WISSARD team’s work will be highly relevant to the mission.

“The WISSARD project went to extra lengths to make sure they recovered pristine samples and also did not deliver or contaminate the lake they were investigating,” Hand said. “From the standpoint of astrobiology, that feeds forward in an important way. We don’t want to bring any hitchhikers we would mistake for life and perhaps more importantly, we don’t want to contaminate or seed those worlds with microbial hitchhikers.”

The Antarctic research was largely funded by more than $10 million in grants from the National Science Foundation. Other funding came from NASA’s Cryospheric Sciences Program, the National Oceanic and Atmospheric Administration and the Gordon and Betty Moore Foundation.

Associate editor Eric Betz can be reached at ebetz@astronomy.com, or follow him on Twitter @ericbetz.

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