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Planetary News: Europa (2006)Europa on Earth: Expedition to the Sulfur Springs of Ellesmere IslandBy Emily LakdawallaJune 21, 2006
A four-person team departs today for an expedition to the top
of the world, where mineral-rich waters seep from the top of a 200-meter-thick
glacier. Sulfur-bearing compounds precipitate from the waters and stain
the glacial ice of Borup Fiord Pass, marking the locations of the springs
with bright yellow splotches that are easily visible from the air. The
place calls to mind the ruddy, sulfur-rich stains on the surface of Jupiter's
moon Europa, and one of the expedition members is traveling there to gather
samples and data that will help with the planning of future Europa missions. The
Planetary Society is proud to enable this Europa analog expedition by providing
key funding. Europa on Earth?Several locations on Earth have been explored for their similarities to geologic, hydrologic, and climatic conditions on Mars, such as the Antarctic dry valleys or the Haughton impact crater on Devon Island. In many ways, Mars is like a cold, dry Earth. But no one had imagined that a useful Europa analog site might exist on Earth until a fortunate series of events brought Borup Fiord Pass to scientists' attention. Expedition leader Stephen Grasby of the Geologic Survey of Canada explains that the site was first noticed by fellow geologist and expedition team member Benoit Beauchamp in 1990. "He was doing some work in the area and had flown over the pass. It was a bad weather route, because it's a low pass that cuts through the mountains. And in the flyover he noticed the yellow staining on the ice. In 1999, when I was up [on Ellesmere Island] working with him, he mentioned it to me, and I made him take me there because it sounded pretty exciting. We realized there were these spring systems, and that's what instigated the following work I've done there." Grasby and Beauchamp returned to the site two more times, in 2000 and 2001. In the meantime, Grasby says, while reading the October 1999 issue of Scientific American, he came across an article written by planetary scientist Bob Pappalardo titled "The Hidden Ocean of Europa." In that article, "Bob comments about the sulfur compounds on the surface of Europa, and that caught my attention. It struck me that this is probably a great terrestrial analog for how things work and what the sulfur compounds might be like [on Europa]. I brought this site to Bob's attention -- I said, 'if you want to see sulfur on ice, here's a great spot.'"
Pappalardo, who is now at the Jet Propulsion Laboratory, agreed. "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. [Borup Fiord Pass] is a place that is stained by sulfur-rich contaminants coming up through and onto glacial ice and teeming with microbes. This is pretty unique for Earth, but may be just the right kind of analog for the type of environment we want to explore on Europa." That's not to say that the chemistry is identical, Pappalardo cautions. "On Europa it's suspected that there's sulfur compounds and evaporite salts, and [at Borup Fiord Pass] we have analogous sulfur compounds and evaporite salts. But we don't know the chemistry of Europa very well. So we don't know if it's the same chemistry, but it's the type of complex geochemistry on ice in a cold environment -- of course, it's not as cold as Europa either -- that we might find there. "On Europa there are ruddy, dark areas that we think might be stained by sulfur compounds and other evaporite deposits, and we want to explore those from orbit with remote sensing, and this site provides a ground truth for that kind of exploration. Someday, we want to land in such areas and sample them and try to understand what the chemistry of the dark patches on Europa is, and whether there is evidence for organics there, and even for life there, not necessarily on the surface, but just under the surface. If we want to do that on Europa, this site provides a great way to test out our remote sensing and other techniques for application to Europa. It's easy to talk about what we see in the lab; it's harder to put that to the test in the field." Expedition to Ellesmere Island
Grasby and Beauchamp departed Calgary this morning for the multi-stage journey to Borup Fiord Pass. They were accompanied by a field assistant as well as Damhnait Gleeson, Pappalardo's doctoral student. Their trip will take them to Ottawa, then to ever-more-remote locations in Canada's far northern Nunavut Territory: Iqaluit on the southern end of Baffin Island, then Resolute on Cornwallis Island. Resolute is the northernmost airport into which commercial airlines fly and is also the stopping-off point for expeditions to Devon Island. A Twin Otter aircraft provided by Canada's Polar Continental Shelf project will take them 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. Grasby hopes for ten days in the field, weather permitting. The field site is located in a north-south aligned valley on northern Ellesmere Island, into which pour many mountain glaciers. On the previous field trips, Grasby found approximately ten of the sulfur-rich springs and seeps near the end of one such glacier. Some springs form large edifices with wide-spreading mineral deposits; others form small cones on the ice; and others merely stain the surface of the ice with yellow sulfur. Over the past three expeditions, Grasby observed the spring activity to lessen; sulfur deposits from one year were completely gone the next. Last year, however, Grasby acquired new sets of aerial photographs of the area, and "there's increased activity; there's a lot of sulfur in the outwash plain again, and there's some new cones that formed on the surface of the ice. It looked much more significant compared to the previous time I've been there. But you know it's such a dynamic system, every time I go, I'm always nervous there'll be nothing. But there's always something interesting at the site."
This year's field season will include a combination of helicopter-based observations and trips to sample the minerals and waters that seep from the springs, Grasby says. "We'll assess what the site looks like this year, where there are outlets and mounds. We'll sample where we can, and then we also want to try and better characterize the spring system, so we'll get samples from other areas as well -- we'll have to hike up the mountain and sample the ice and snow and various potential water sources. We'll also be looking at geologic mapping at the area. It's an unusual geologic structure that makes the valley in the first place, and it's only been very coarsely mapped in the past, so it's really not well understood what the local geology is. So we'll try to identify what the rock units are and what the structural geology is," an activity in which team member Benoit Beauchamp will be playing the central role. The team member who will be most focused on the site as a Europa analog is Pappalardo's student, Damhnait Gleeson, of the University of Colorado. Pappalardo says that her goal will be "to try out the kinds of remote sensing techniques we'll eventually send to Europa. Damhnait has a field spectrometer, and she'll get data both on the ground and from the air, from the helicopter. Then we'll have the geochemical measurements that Grasby will be making on the water samples from the site, to provide ground truth." Pappalardo hopes that this expedition will lead to a larger one in the future. "This is a mini version of the expedition we'd like to do; I can imagine doing a lot more in this field area." For example, "we'd like to use radar at this site and map out the plumbing -- how the ice cracks, and how melt flows within it. That's something we want to understand for Europa. And maybe, someday, we'll be able to do it." In the meantime, the 2006 team will be reporting back via The Planetary Society Weblog on the progress of their field trip. "When we were asked to provide key funding to enable this expedition," says Planetary Society Director of Projects Bruce Betts, "The Planetary Society was delighted to be able to say yes. The Planetary Society and its members have long supported planetary analog studies and have been strongly advocating a mission to Europa. This expedition bridges both concepts."
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