If you're looking for life beyond Earth, Jupiter's ice-encased moon, Europa, beckons as one of the solar system's most promising destinations. If you're looking for a possible analog to Europa on Earth, then head for frigid Ellesmere Island above the Arctic Circle.
As long-time advocates of launching a dedicated mission to Europa, The Planetary Society is helping sponsor an expedition to Ellesmere Island to study glacial springs that appear similar to features on the distant moon. Viewed from the air, the yellow stains of active sulfur springs, seeping from a 200-meter-thick glacier on the island, somewhat resemble dark, mineral-rich patches that splotch the icy surface of Europa.
"The expedition becomes even more important now that there is a better chance of NASA starting a Europa exploration mission next year," said Louis Friedman, Executive Director of The Planetary Society, referring to recent U.S. congressional support for the mission.
Bacteria are known to live in the Ellesmere Island sulfur deposits. Although some sulfur-loving bacteria flourish in extremely hot environments, the Ellesmere bacteria are particularly interesting from an astrobiological perspective because they live in a cold, Arctic environment.
The four-person team is led by Stephen Grasby of the Geologic Survey of Canada. Other expedition members are Benoit Beauchamp, Executive Director of the University of Calgary's Arctic Institute of North America, who first noticed the sulfur springs staining the glacier; Damhnait Gleeson, a doctoral student at the University of Colorado in Boulder, who works with planetary scientist Bob Pappalardo of the Jet Propulsion Laboratory; and University of Calgary graduate student Marie-Eve Caron.
The public will be able to join the expedition vicariously via updates at The Planetary Society's weblog.
The expedition will make helicopter sweeps over the glacial ice of Borup Fiord Pass where the springs are located and take in situ trips to sample the seeping minerals and waters.
"We'll assess what the site looks like this year, where there are outlets and mounds," said Grasby. "We'll sample where we can, and we also want to try to better characterize the spring system, so we'll get samples from other areas as well."
A key goal for Gleeson is to perform spectral analysis of the site, using techniques analogous to those planned for Europa. But here on Earth, samples can be brought back to the laboratory for comparison to what is measured remotely. Gleeson hopes to be able to remotely identify favorable habitats here on Earth, so that in the future we can have a better chance of doing this at Europa.
The team will also work on refining geologic maps of the region, and they will return microbial samples for laboratory analysis, in order to determine "who" is living there and how the cold-living organisms metabolize. This will be Grasby's and Beauchamp's fourth visit to the springs - the first since their 2001 expedition.
Pappalardo says, "I think the site is arguably the best terrestrial analog for near-term Europa exploration, for the kind of exploration that an orbiting Europa spacecraft or the first landed spacecraft would do."
While the site at Ellesmere Island appears similar to the mineral patches observed on Europa, further study is necessary to analyze the geochemistry of Jupiter's moon. Scientists hope future missions to Europa will provide an opportunity to study the sulfur compounds of the dark patches, both from orbit and eventually from a lander on the surface.
"There is no pure analog on Earth for minus 184-degrees Celsius, airless Europa, but Ellesmere allows us to study a partial analog, and helps us frame the questions we need to ask and the experiments we should conduct when we are able to mount a Europa mission," said Bruce Betts, The Planetary Society's Director of Projects. "One of those key questions will be whether sulfur-rich vents on Europa show evidence of organics, a sign that life might have developed beneath Europa's icy crust.
The expedition is now en route to Ellesmere Island (81ºN, 82ºW), a complicated journey that includes stops in Iqaluit on the southern end of Baffin Island and Resolute on Cornwallis Island. Resolute is the northernmost airport into which commercial airlines fly. A Twin Otter aircraft provided by Canada's Polar Continental Shelf project will fly the team to a spot on the tundra of Ellesmere Island, 40 kilometers (25 miles) south of the field site. From there, a helicopter from the nearby Eureka weather station and military outpost will carry them to the site. The expedition plans to remain in the field for 10 days, weather permitting.