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Two ships, one mission

Research cruise pairs U.S., Swedish vessels on 3,000-mile-long journey

 

It’s not the fastest route to reach McMurdo Station. But for several dozen scientists traveling aboard two research vessels over the next two months, the trip is all about the journey and not the final destination.

The Swedish icebreaker Oden and U.S. Antarctic Program (USAP) research vessel Nathaniel B. Palmer will cross about 3,000 miles of ocean between Punta Arenas, Chile, and McMurdo Station. Scientists aboard the vessels will study everything from invasive crabs creeping up the continental slope to decades-old pollutants infiltrating the polar food web.

“Imagine driving across the United States at 12 miles per hour. That’s basically what we’re doing,” said Patricia Yager, chief scientist aboard the Palmer from the University of Georgia.

Yager is the lead principal investigator on the ship-based project called Amundsen Sea Polynya International Research Expedition (ASPIRE). The ASPIRE project brings together a multidisciplinary group of mostly Americans and Swedish scientists to study an area of open ocean surrounded by ice that is the most biologically active polynya in the Southern Ocean.

The Palmer is scheduled to leave Punta Arenas at the end of November, carrying both the ASPIRE team and a second group interested in learning more about invasive crabs that appear to be moving into more shallow areas, possibly threatening organisms on the continental shelf that have evolved without such predators over tens of millions of years.

The ship will first make its way to Marguerite Bay in the middle of the Antarctic Peninsula, where a species of king crabs has been previously spotted on the continental slope. The Palmer will then head farther south, eventually rendezvousing with the Oden to swap scientists.

The team hunting for invasive crabs, a project led by Richard Aronson and James McClintock, will continue their work within the sea ice on the Oden. Meanwhile, the Palmer will enter the 24,000-square-mile polynya in the Amundsen Sea.

It’s a rare pairing of two polar research vessels, according to Addie Coyac, a science planning manager for Raytheon Polar Services (RPSC), the prime contractor to the National Science Foundation (NSF), which funds and manages the USAP.

Primarily an icebreaker capable of cutting through about 2 meters of ice at 3 knots, the Oden serves as the muscle on this expedition. While the two ships will work on separate projects for the most part, the Oden will be available to escort the Palmer into the polynya should the surrounding sea ice prove too stout. The Palmer is also an icebreaker but not of the Swedish ship’s strength.

“It will be interesting to see what the ice does this year and how it works out,” Coyac said.

Since 2007, the NSF has had an agreement with the Swedish Polar Research Secretariat and the Swedish Maritime Administration to use the Oden to break a channel in the sea ice to McMurdo Station. The channel allows cargo and fuel ships to access the research station at the end of each austral summer to resupply it with everything from construction material to food to fuel for power plants, ships and planes.

The ship’s unique hull design (it is shaped like a flat-bottomed skiff) allows it to break ice not by smashing into it, but rather by riding up onto it and using the ship’s weight to crack it. In addition, a pump system quickly moves hundreds of tons of water within the Oden from one side to the other, rocking the ship in heavy ice so that the reamers break the ice at the sides of the ship.

The Oden is also a research vessel, so American and Swedish scientists have used it previously for various projects. However, this year researchers were encouraged to submit collaborative proposals, meaning both ships will carry large contingents of U.S. and Swedish investigators working on similar projects.

“It’s a great opportunity to do international and multidisciplinary science to understand a changing ecosystem. That’s what I’m excited about,” Yager said.

Both ships will have a full workload during the two-month expedition.

The Palmer will also be busy recovering 14 moorings that were anchored to the seafloor in the eastern and central Amundsen Sea in January 2009 during a science cruise led by Stan Jacobs, a research scientist at Lamont-Doherty Earth Observatory at Columbia University.

Jacobs and his colleagues hope the moorings will reveal new details about a mass of relatively warm circumpolar deep water that intrudes upon the continental shelf, helping melt ice from below in the Amundsen Sea area.

“Now they want to go back and get as many [moorings] as they can. They have about a week’s time … to recover what they can,” said Adam Jenkins, a science planning manager for RPSC who is coordinating the support for the Palmer side of the science expedition.

Meanwhile, the Oden will take over the Aronson-McClintock expedition, led by U.K. scientist and collaborator Sven Thatje in the field, as it cruises toward McMurdo. Several other groups will also be aboard the Swedish icebreaker, including a two-person team led by Rebecca Dickhut from William & Mary College who will serve as the U.S. chief scientist on the Oden.

Dickhut is interested in how persistent organic pollutants like DDT, largely banned since the 1970s, has made its way into the polar food web. Additionally, she and her colleagues will use these chemical tracers to learn more about the year-round feeding ecology of seabirds and mammals with Swedish scientists on the Oden.

Also aboard the Oden will be a U.S. team studying the physics of sea ice under principal investigator Steve Ackely with the University of Texas at San Antonio, while a second group will look at the biological activity associated with sea ice, a project led by Kevin Arrigo at Stanford University.

The two ships are scheduled to arrive at McMurdo Station in mid-January. The Oden will primarily break ice, lending its onboard helicopter for scientists to access nearby islands that require crossing open water — something McMurdo’s helo fleet isn’t capable of doing.

Meanwhile, the Palmer will pick up four fresh science teams from McMurdo for a month-long science cruise focusing on both physical and biological oceanography. Finally, in the waning days of the summer field season, the vessel will reverse course back to Punta Arenas with a shipful of scientists, led by Jim Swift of Scripps Institute of Oceanography.

Swift and colleagues will perform a variety of physical oceanographic measurements, looking at processes like ocean circulation and the carbon cycle. The Southern Ocean is a critical sink for carbon. Once locked into the deep ocean, carbon can remain out of the atmosphere for hundreds of years, helping to reduce the buildup of CO2 in the atmosphere that’s warming the planet.

Jenkins said that in addition to deploying moorings en route to Punta Arenas, the return cruise aboard the Palmer will collect any outstanding moorings that the vessel didn’t grab the first time across the Amundsen Sea.

The two-ship operation, while the first of its kind for the USAP, may not be the last, Jenkins noted.

“It may lead to quite a bit more. It’s a proof of concept too see if it works, if it’s needed,” he said. “It gets a lot of science done, if it does work.”

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Curator: Peter Rejcek, Antarctic Support Contract | NSF Official: Winifred Reuning, Division of Polar Programs