Beneath Arctic ice pack, teeming life holds extraterrestrial clues
Microscopic organisms thrive in polar-ice 'brine channels' whose conditions mirror some of those found in space.
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Studying life in polar sea ice requires a major investment. The icebreaker Amundsen had to be retrofitted with innovative design features and state-of-the-art laboratories for polar research. Still, the ship has limits. According to the Amundsen commander, Lise Marchand, the ship has rammed a few times this winter into pressure ridges – where plates of sea ice ride up on top of one another. "We occasionally get stuck," says Captain Marchand. "The way to break loose again is to send ballast and fuel from one compartment to another, to lighten the ship's stem." Crew members and scientists then use gas-powered ice augers and chain saws to loosen the ice jam.
Deming has been doing fieldwork in the Arctic for more than a decade. Her work before this project was aboard a Canadian icebreaker off Greenland.
"We were focusing on organic polymers, a kind of gelatinous material released by microbes into the brine pores that acts like antifreeze," she says. "When temperatures are very cold, liquids become thin films. As the microbes produce this stuff to protect themselves, they change the physics of the ice, keeping the pores liquid. This is an unusual case where biology affects physics."
A eureka moment
Then, on returning to Seattle, she had her "eureka" moment. She was struck by images of Europa captured by the National Aeronautics and Space Administration's Galileo spacecraft mission, showing a lunar-ice surface full of lines, domes, and streaks. It reminded her of the Arctic and made her wonder about parallels. "If you allow life to have extraordinary capabilities of living in tiny patches of ice," Deming says, "then some astrobiologists would say that the moon and Mercury, as well as comets, have a likelihood of life."
If there is life out there, Mr. Lipps says, it could well be carbon-based. "Carbon is the only element that is interactive and will make long molecules under those conditions…. The elements of carbon-based life are everywhere in the universe," says Lipps, who thinks the possibility of "hydrothermal seeps" on the floor of Europa's oceans means that hot conditions could also exist there, raising the prospect of originating life.
The astrobiology community is hoping that a mission to Jupiter, currently being discussed by NASA, will provide more opportunities to look for life on Europa.
A number of frozen planets and moons have the potential to sustain microscopic life, scientists say. They include:
Mercury – The smallest planet of our solar system and the one closest to the sun is believed to have ice in permanently shaded craters at its poles.
The moon – Earth's satellite may have ice at its poles mixed in with regolith (a dry blanket of loose soil and rocky fragments).
Mars – Long the subject of speculation about life, this planet has water ice at both north and south poles and frost has been detected in higher elevations of the volcanic Tharsis region.
Europa, Ganymede, and Callisto – Three of Jupiter's ice-covered moons, discovered by Galileo in 1610, may have liquid-water oceans under the ice crust at the surface. If oceans exist below the ice, it may be kept warm by tidal heat.
Enceladus – This tiny moon orbiting Saturn appears to have spewing ice geysers on its surface.
"Jupiter's moon Europa is the outstanding target because of the water under its ice and the tectonically active icy crust," says Jere Lipps, an astrobiologist at the University of California, Berkeley. "Another of Jupiter's moons, Ganymede, is less likely but still a candidate, because it may also have water under its much older icy crust."
Saturn's moon Titan is another possible host, Mr. Lipps says, given the presence of many carbon compounds, "although that's not necessary, given the abundance of the elements of life in general in the solar system," he says.