Sunday, November 26, 2000

Pinpoint precision: Geographic locators are accurate to within tenths of an inch

Published in the Antarctic Sun

Several scientists in the U.S. Antarctic Program use specific measurements and locations on the surface of the Earth as key elements in their research. They watch many processes, including
the movement of glaciers, growth or shrink rates of ice sheets and rock layers and the melting of patches of snow in the Dry Valleys.

These researchers use the Global Positioning System, originally created for combat use by the U.S. Defense Department, to locate themselves and their study areas very specifically. At McMurdo Station each summer are GPS experts who provide equipment and training for about 20 science groups on the continent.

“We’re supporting grantees who are using GPS for their field research,” said project leader Bjorn Johns, of the University NAVSTAR Consortium (UNAVCO), a group of 100 academic institutions, including the National Science Foundation, promoting the use of high-accuracy GPS for scientific research.

Many people on the Ice and in the U.S. have their own handheld GPS units, which cost around $200. “It’s become a national utility,” Johns said.

Commercial handhelds provide accuracy to within about fifteen feet of an actual location, Johns said. By contrast, the equipment Johns and his colleague Chuck Kurnik issue are accurate to within tenths of an inch, cost around $15,000 and involve a plattersize antenna and laptop computer-size receiving box.

GPS is based on a group of satellites orbiting Earth and several ground stations monitoring them. The satellites broadcast their position in space and the exact time from an on-board atomic
clock. By receiving the signals from several satellites, a GPS unit on the ground can calculate its location.

But that can be difficult at high latitudes because the satellites don’t pass directly overhead, which would give the best possible readings. “They’re all low on the horizon in the polar regions,” Johns said.

All of the positions calculated are relative to other, fixed, known locations. To be precise, measurements need to be compared very carefully with the exact trajectories of the satellites at the time of the reading.

“That typically means collecting and post-processing data,” Johns said. That process can take a couple of days, he said. Some groups need Johns and Kurnik to do GPS portion of their work, while other researchers need technical assistance or data-processing help.

Johns and Kurnik also install both permanent and temporary stationary GPS stations to monitor ongoing geologic processes and to improve accuracy of nearby readings.

This season, they put a station on Mount Erebus to watch how underground activity changes the volcano’s surface. “If there’s any inflation or deflation of the volcano relative to McMurdo we’ll see that,” Johns said. If anything significant happened on Erebus, or anywhere else with a permanent GPS monitoring station, the data would be valuable for scientists.

“When an event occurs, you’ve captured it, with pre- and post-event data,” Johns said.

Another important element is fixing the exact antenna position to the ground. If a measurement is accurate within fractions of an inch, a human error in antenna placement for observation could
appear to be a large fluctuation in surface movement.

To provide a stable platform, Johns and Kurnik sink a metal rod into the rock or ice and affix a leveling platform to the rod. The antenna screws onto the platform.

Each reading, then, is taken from the same location relative to the rod. If a location change is measured, it means the rod has moved, and therefore the rock or ice surrounding the rod has moved.

This type of measurement is possible around the world using base stations and satellite readings anywhere on the surface of the Earth. But Johns said Antarctica is where GPS gets used most heavily. He and Kurnik may support five science projects during the rest of the year, and more than 20 during the summer field season on the Ice.

The GPS work helps influence future research, Johns said. This season at Icestream C, a group wanted to drill an ice core in an area where the glacier isn’t moving very quickly. Because of GPS
surveying last year, they knew where one was.

GPS is also used to map the atmosphere. Since GPS uses radio waves, which behave differently as atmospheric conditions change, GPS readings at known locations can show variations in
the ionosphere and troposphere through changes in radio waves along different paths.

Johns and Kurnik don’t directly interact with the atmospheric mapping projects, which are not based in Antarctica, but help people use GPS in all kinds of ways. “Everyone has something they want measured,” Johns said.

Swedish Polar Ambassador visits Ross Island

Published in the Antarctic Sun

The New Zealand Antarctic Program played host to the Swedish polar ambassador, Eva Kettis, last week.

She had been in Hobart, Tasmania, Australia, for a meeting of the Commission for the Conservation of Antarctic Marine Living Resources and was invited to be a guest at Scott Base.

After several days on weather hold in Christchurch, Kettis arrived on the Ice for her second visit. Her first visit was to a site on the Antarctic Peninsula where a hut was built by an early Swedish Antarctic explorer, Otto Nordenskjold, in 1901.

Sweden, which signed the Antarctic Treaty in 1984, maintains two small summer-only camps in Queen Maud Land and cooperates with Finland and Norway in areas of logistics and operations.

“We have subscribed totally to the Antarctic Treaty goals,” Kettis said.

While she is the ambassador for both polar regions, Kettis said she concentrates most of her
effort on the Arctic. “That’s perhaps nearer to our heart,” Kettis said.

She works with the Arctic Council, a group that includes the eight countries that border the Arctic and several groups of Arctic indigenous people. “That is quite unusual for intergovernmental cooperation,” Kettis said.

The political issues, she said, are very different in the north and south polar regions. For example, since the Arctic is largely ocean, no country can make territorial claims. Research,
on the other hand, is similar in the two areas.

“The science has a clear bipolar aspect,” Kettis said. “I think it has not only polar aspects but global aspects.”

On her trip to the Ice, she visited Ross Island’s historic huts, various field camp locations around the Ross Sea and in the Dry Valleys, and visited McMurdo, where she was particularly
impressed by the mawsonii in the old aquarium.

“I never thought I would see a big toothfish,” Kettis said.

As well, she toured Scott Base and liked what she saw. “They are very well equipped and it
works very well,” Kettis said.

She was unable to leave on schedule because of the weather, which frustrated her a bit, but Kettis said she was glad to be able to see this part of “this huge and beautiful continent.”

Sunday, November 19, 2000

Mind is in Maine

Published in the Antarctic Sun

On the windowsill above Ted Dettmar’s desk sits a picture of him taken five years ago. He looks every bit an old-time Down-East farmer of Maine. His ballcap is pulled down over unruly hair, his long red beard hanging over a canvas jacket. His feet are sunk deep into a pair of rubber Wellington gumboots, and he sits atop a piece of farm machinery that has seen better days.

In the picture, Dettmar has one horse reined in very tightly and the other let all the way loose. That’s how he handles his world, letting things go along their own way and then taking charge at specific moments that make all the difference.

Dettmar, 36, grew up in suburban Arlington, Virginia, the youngest of six children in a military family. His family lived all over the world while they were growing up and have all settled near the home their parents retired to, the one in which Dettmar grew up.

It’s Ted who is now wandering the globe, with this picture and a very specific goal.

“I want to live as close to the land as possible,” Dettmar said, “to get to know every tree, every bush, the soil types, the rock types.”

Here in Antarctica, that may seem a very easy dream: No trees, no bushes, no soil. And there’s not all that much rock, either. But he’s talking about New England, and a vividly simple life on a

Dettmar knows it’s a long way from the Ice, where everything is imported by cargo plane or container ship from the rest of the world, where the landscape can and will kill.

“The irony is not lost on me,” he said.

Now known as one of McMurdo’s eminent historians of the Heroic Age of Antarctic exploration, Dettmar didn’t know much about Antarctica until just a few years ago.

The first thing he read about the Ice was Apsley Cherry-Garrard’s book, The Worst Journey in the World.

“That’s the typical first book,” Dettmar said. Just as he finished that, he came across another book.

“Somebody handed me a copy of Endurance and it had the crew list,” he said. One of the names on that list was Thomas Crean, a name he recognized as having been part of Scott’s Terra Nova
expedition from 1910 to 1913.

“I found out there were these guys who were just indestructible, just made of stone,” Dettmar said. They just kept coming back to Antarctica on expeditions.

When he got to McMurdo as a GA in 1994, he took a tour of the Discovery hut, given by someone who didn’t know what he was talking about.

“The tour guide was abysmal. The guy knew nothing,” Dettmar said. A history major in college, Dettmar bristled.

“People deserve to know more. These are interesting stories,” Dettmar said. “I thought, ‘We need people who can bring these places alive.’ I said, ‘That’s going to be me.’”

After working in waste management and now for the Field Safety Training Program, Dettmar now shares with people not only the history but also the practical lessons learned by polar explorers.

Even so, he doesn’t claim to be following in the footsteps of early explorers like Scott and Amundsen.

“There’s no comparison,” Dettmar said. "Amundsen’s story is the story of what people can accomplish," he said, likening it to the construction of the George Washington Bridge over the
Hudson River.

“Scott’s and Shackleton’s stories are the story of what humans can endure,” he said. “Everything they did was a close call.”

That’s not how Dettmar likes to do things, though some might disagree.

“I do not consider myself to be adventurous in the least,” he said.

He has been doing search-and-rescue since his junior year in college, recovering light aircraft crashed in the Shenandoah Mountains of Virginia, and lived for five winters in the Harvard Cabin in Huntington Ravine on New Hampshire’s Mount Washington.

With that experience, Dettmar got out into the deep field quite a bit as a GA, and was a rare first-year selection for the secondary SAR team. He’s been on the primary SAR team since his second year.

Now he’s the lead field safety instructor, in training his coworkers to do their jobs as best they can. He still takes the lead in sea ice training, which is his specialty, and keeps watch while
the rest of the instructors teach and learn and do.

“I think I can do it as long as I’ve got people underneath me who are more qualified than I am,” Dettmar said.

As much as the job, he really likes being here and being part of history.

When he leaves for the last time, he said, he expects he’ll be bawling. “I’m always ready to come back down here.”

Diving for science

Published in the Antarctic Sun

Most scientists in the U.S. Antarctic Program study things on or above the ground. Some even explore the sky or faraway galaxies. But a select few regularly descend into Antarctic waters to collect material and information for their research.

On average, 20 divers make 600 dives a year in McMurdo Sound, the Dry Valleys, near Palmer Station and based from the program’s two research vessels, said scientific diving coordinator Rob Robbins.

The highest number of dives recorded in any one year was 908 in 1984, Robbins said. The average dive lasts 40 minutes, though some have gone longer than 90 minutes. The water in McMurdo Sound is 28.5 F (-2C), and near Palmer it’s only slightly warmer, at
30 F (-1C).

This summer season, six research groups, five based at McMurdo and one at Palmer, will include16 divers. The GLOBEC survey of the Southern Ocean ecosystem, based on the Laurence M. Gould and Nathaniel B. Palmer research vessels, will have two groups diving in March.

Less commonly, Robbins will dive to support specific projects that don’t have their own divers.

“Most groups bring down whatever dive labor they require,” Robbins said.

Scientists dive for many reasons, including photographing marine life, collecting specimens for lab work and maintaining underwater equipment.

“The facilities here are fabulous for diving,” said John Heine, the U.S. Antarctic Program’s advisor for research diving. “The diving conditions are really great. The support from Rob is really what makes it happen.”

One reason to dive in McMurdo Sound is that the low water temperature attracts deepsea wildlife to shallow water with little light filtering through the sea ice.

“The sound is fairly interesting,” Robbins said. “You see animals in the sound you would normally see in deep water, but at diveable depths.”

The depth at which wildlife are observable is important, because diving deeper than 130 feet and for extended periods is not allowed for scientific research. Deep diving is more complex and dangerous, even in warmer waters. In Antarctica, the margin of error is slimmer, so divers take more precautions.

“ We don’t allow decompression diving,” Robbins said.

That’s when a diver needs to pause on the way back up to the surface to adjust to the difference
in pressure.

McMurdo Station has a recompression chamber, originally installed in 1984 to comply with federal safety regulations for construction diving. After the construction finished, Robbins
said, station management decided to keep the chamber in case of dive accidents.

Since then, nine people have needed treatment. Four were aviators who had decompression
problems after accidents in which their airplanes depressurized at altitude. The other five patients were divers.

“Every one was a complete resolution,” Robbins said.

Robbins runs the recompression chamber with a volunteer crew of six, as well as a doctor
and a medical technician from the medical department on station.

Palmer Station has no chamber, though there is one at the nearby British base, Rothera, as well as in Punta Arenas, Chile.

Robbins works hard, though, to avoid accidents, and gives each dive group a firstaid kit and an oxygen kit.

“ We provide a lot of safety equipment,” he said.

He also ensures that science divers know how to move around underwater while wearing a dry suit, which keeps them warmer than a wetsuit would.

“It’s really the dry suit that’s different from most diving,” Robbins said.

A dry suit traps a lot more air than a standard buoyancy control device. Therefore, as
the divers change depth, their buoyancy changes rapidly.

Each season, each diver has to do a refresher or orientation dive to qualify for Antarctic diving, because some of the things are different here. For example, most underice diving courses teach divers to use tethers.

But here, the water is so clear, Robbins said, that they don’t need tethers if they appropriately
mark the holes.

“Here the visibility’s good. When visibility drops we use the tethers,” Robbins said.

There are two ways to breathe under water. If divers use scuba tanks, at least two divers must be in the water, to help each other in the event of an accident.

When a diver is breathing from a surface supply of air, the system not only permits twoway
communication between the diver and someone on the surface, but a rescuer can follow the air hose from the surface to a diver in distress. So a standby diver is still present, suited up and ready to swim, but is on the surface.

With only one diver using air at a time, they can take turns diving and being the standby diver for each other, accomplishing more in one outing.

“ You can do a lot more work,” Robbins said.

Also with surface supply, a diver is more comfortable in the water, Robbins said.

“It’s quite a bit warmer,” he said. “Your face is covered.”

Robbins said he would like to be doing more commercial construction diving, but he’s pretty happy with the science support end of things as well.

“This is a lot more scenic,” he said. “I’ve potentially got the best job in the program.”

Solar flare shuts down continental communications

Published in the Antarctic Sun

MacOps bills itself as the Voice of Antarctica. The radio operators there talk to people all over the continent and elsewhere around the world on high-frequency and very high-frequency radios.

Thursday, just before lunch, the continent got a sore throat.

All the HF radios went quiet, broadcasting white noise instead of voices from all over.

“It was pretty eerie,” said Paula Elliott of MacRelay, which also monitors all radio frequencies.

A solar flare had sent a mass of charged particles out from the sun into the Earth’s atmosphere. Those charged particles had disrupted the ionosphere, the layer of Earth’s atmosphere that
reflects HF radio waves, preventing transmission of HF waves around the globe.

The radiation, the fourth largest storm of its type since 1976, caused some rearrangement
of communications and transport schedules on the continent.

“Camps were unable to check in,” Elliott said. “People were technically overdue for their
check-ins, though we knew why.”

If camps miss their check-ins under normal circumstances, rescue missions are launched. This
time, though, radio operators waited and worked around the situation.

They had lost contact with South Pole Station, Byrd Surface Camp, Siple Dome, Byrd Glacier, as well as the Olympus Range and Lake Vida, which are in VHF “dead spots” in the Dry Valleys.

Communications with the Pole were possible on the Internet during the Pole’s satellite window. The people at Vida had to climb a hill to hit a VHF repeater.

“We didn’t expect it to be as big as it was,” said MacOps coordinator Shelly DeNike.

The camp at Icestream C was put in during the communications blackout.

Normally, an airplane can’t leave a camp put-in until the camp radios MacOps on HF. This time, though, the camp was only able to talk to the plane on the ground. The solar flare’s energy prevented them from talking farther away.

Other than that small glitch, everything was fine.

“We’ve been pretty much prepared for this to happen,” DeNike said.

The larger field camps have emergency beacons they can set off if all else fails, just like if an aircraft crashes or a boat is in distress at sea. Had anything truly disastrous happened, they could have activated the beacon.

After two days without contact from Byrd Surface Camp, an airplane went out of its way to fly over it to make contact. Pilots helped by contacting camps along their flight routes.

“When they would fly in the vicinity of field camps they would call them,” DeNike

Camp managers knew this might be a problem. Before going into the field, they had been briefed that HF problems might occur in this year of high solar activity.

In terms of air traffic control, everything also went smoothly with what air traffic manager Dusty Barrett called “a little bit of creative scheduling.”

Before planes left McMurdo, controllers gave pilots instructions for flying both to and from the Pole; normally they clear flights for only one direction at a time. MacCenter, the hub of air traffic control at McMurdo was only able to talk to the planes while they were within line-of-sight.

In a contingency set up last year, they had two controllers in Christchurch, New Zealand.

The controllers in McMurdo talked over the phone to Christchurch, which relayed messages over a satellite communication link to the planes.

“Once the HF went down we had to be a little bit creative,” Barrett said.

They also used Iridium satellite phones, Barrett said. Pilots continued to use HF, sending their position reports “in the blind,” without knowing if they were received, in the hope that MacCenter could hear them.

“Sometimes you can receive but you can’t transmit,” Barrett said.

This is the second full blackout since Winfly, but there have been partial blackouts where only lower frequencies were cut off.

This type of event has happened in the past, but only for 24 to 48 hours, Elliott said. This time it was Saturday evening before things came back, a shutdown of nearly 60 hours.

“We’ve seen a lot more activity than we had last year,” Elliott said.

It may have to do with a peak in the 11-year cycle of solar activity. Sometimes these effects from flares are predictable, and this time there was some warning. But the loss of HF communications was rapid.

“It happened right away,” DeNike said.

Things are back to normal now, Elliott said, but it could happen again anytime, and without a lot of warning.

“They hit without much notice,” she said.

Exploring the plateau

Published in the Antarctic Sun

The U.S. segment of the International Trans-Antarctic Scientific Expedition left Thursday for Byrd Surface Camp to begin this season’s traverse of the West Antarctic ice sheet.

The project is a multi-national effort in which the U.S. component this year involves 10 research institutions and five areas of study: meteorology, surface glaciology, geophysics, remote sensing and ice coring.

“It’s five coordinated disciplines,” said Paul Mayewski, coordinator of the U.S. traverse group.

Last year was the first of this four-year project that will end at the Pole in 2003. The information the team collected last year is already helping improve scientists’ understanding of the world’s climate.

The data is specific to the region of West Antarctica where the traverse will occur, but it shows effects of regional and even global weather and climate systems.

“What we’re looking for isn’t just an understanding of Antarctica,” Mayewski said.

By looking at snow layers in Antarctica ice sheets revealing the last 200 to 500 years of the Earth’s climatic history, ITASE groups across the continent have already learned about the
relationship of certain Antarctic weather patterns to large-scale climate phenomena like El NiƱo.

“We already have seen some very interesting results,” Mayewski said.

The team is also comparing the results from their work in the Antarctic to similar work in the North Atlantic, another powerful element in the engine of Earth’s weather. While small changes are localized, Mayewski said, larger alterations are visible in ice cores from both ends of the globe.

This field season, the traverse team will cover 1,200 kilometers in a triangular path starting and ending at Byrd Surface Camp. During the drive, they will use downward-looking radar to map the strata in the ice beneath the route. They will also have a shorter range crevasse detector radar unit operating to keep the vehicles and researchers safe out on the plateau.

At roughly 100-kilometer intervals, they will stop for a few days to drill a 200-meter ice core. The core itself and the hole it leaves show the chemical and physical properties of the layers of

They will identify specific layers in the cores that can be cross-referenced to the radar data, allowing them to follow snow layers for hundreds of miles.

“It’s almost like a three-dimensional ice core,” Mayewski said.

The data they get from the cores and from the radar shows indicators of the extent of the sea ice, activity of marine life and duration of polar stratospheric clouds in recent centuries, Mayewski said.

This year the team will be able to haul more equipment and better shelters, because they have a Challenger instead of one of the two Tucker Sno-Cats they used last year. The other Sno-Cat will
continue the journey this season.

As the project progresses, Mayewski said, the setup and takedown at either end of the traverse will become more streamlined, as vehicles and supplies are left to spend the winter on the plateau.

“We should be able to go in with a very small amount of C-130 support,” Mayewski said. This is a big efficiency advantage, he said, as compared with individual field camps.

“There are 10 institutions that can potentially be served by two to three flights in and two to three flights out,” Mayewski said, adding that fuel airdrops will also be part of the support of
the field traverses. This year they expect to use seven flights in and four flights out.

To choose its exact route, the team uses satellite photos to avoid crevassed areas and other potentially problematic sites. But they also confirm satellite pictures by reporting on surface conditions and comparing that information to the pictures taken from space.

In addition to their own work and contributions to wider projects like the International Geosphere and Biosphere Project, one of this year’s shallow cores is at a possible deep-core site like the one at Siple Dome.

“This is a return of the 1960s style of science in this region, with 21st century technology,” Mayewski said.

Sunday, November 12, 2000

What's in a name? The seventh continent bears the names of heroic explorers and heavy equipment operators alike

Published in the Antarctic Sun

When explorers first set eyes on Antarctica, “Terra Incognita” wasn’t just an unknown land,
it was an unnamed land, too.

They soon took care of that, naming prominent geographic features after themselves, their ships and those who gave them financial backing.

In 1841 Capt. James Clark Ross named the Ross Ice Shelf in his own honor; he named mounts Erebus and Terror for his ships. Capt. Robert Scott, 60 years later, named Cape Armitage for his second-in-command and Minna Bluff for the wife of Sir Clements Markham, one of Scott’s primary sponsors.

But Antarctica is a big place. There are still a lot of points, bluffs, peaks, glaciers, nunataks and other formations that need labeling. Since 1947, the U.S. Board on Geographic Names and its Advisory Committee on Antarctic Names have handled that task.

To decide on designations names are first categorized as personal or non-personal.

The latter include commemoration of events (for instance, Jubilee Peak), ships (Glacier Bight), Antarctic-related organizations (USARP Mountains) and descriptions of features (Turtle Rock).

People’s names are, of course, also used.

They are assigned based on the level of a person’s contribution to Antarctic research or history, and on the type of geographic feature.

First-order features are large, such as regions of land, large glaciers, ice shelves and large
mountain ranges. They are named after leaders of major expeditions, towering figures in Antarctic history and donors to Antarctic research.

Second-order features include peninsulas, significant mountains, prominent coastal features and islands. They are named for people who have played significant but lesser roles.

Third-order features include nunataks, cliffs, rocks and anchorages. They are named for people who have supported Antarctic endeavors.

Various people in the U.S. Antarctic Program have been immortalized on the Ice, from top dogs at the National Science Foundation to long-term program employees (see sidebar). NSF director Rita Colwell was once an Antarctic field researcher; a mountain now bears her name. NSF representative Dave Bresnahan and his boss Erick Chiang both have mountains named for them.

Chuck Gallagher served in the U.S. Naval Support Force, Antarctica and then worked for Antarctic Support Associates before dying at McMurdo Station on May 1, 1997. A ridge bears his name.

In alphabetical order, here are some Antarctic geographic features named after some members
of the U.S. Antarctic Program who will be on the continent this season. Their accomplishments are listed in brief. For a complete list and searchable database, visit the U.S. Geological Survey’s Antarctic names web site at

Ainley Peak is named for David Ainley, penguin and skua researcher.
Alcorta Rocks is a nunatak named for Jesse Alcorta, hazardous waste specialist
and cryogenic technician.
DeVries Glacier is named for Art DeVries, long-time biologist at McMurdo Station.
Guthridge Nunataks are named after Guy Guthridge, director of polar information
services for the NSF and chair of the Advisory Committee on Antarctic Names.
Joyce Peak is named for Karen Joyce, who has worked in computer science support for 10 years.
Kennedy Ridge is a ridge named for Nadene Kennedy, NSF’s polar coordination specialist.
Kottmeier Mesa is named after Steve Kottmeier, who’s been a scientist and administrator with the program since 1988.
Krall Crags is a pair of summits named for Sarah Krall, who has worked in the program for over 10 years.
Kyle Hills is a group of hills on Ross Island named for Phil Kyle, who has studied Mount Erebus for 28 years.
Lettau Peak is named for Bernhard Lettau, ocean and climate sciences program manager at the Office of Polar Programs.
Mount Bresnahan is named for Dave Bresnahan, current NSF representative at McMurdo Station.
Mount Chiang is a mountain named after Erick Chiang, manager of operations for polar programs.
Mount Melton is a peak named for Terry Melton, who has worked as an engineer and manager at Palmer and McMurdo stations since 1981.
Palais Glacier is a glacier named after Julie Palais, field researcher in Antarctica and NSF polar glaciology program manager. Palais Bluff also bears her name.
Robbins Hill is named for Rob Robbins, science diving coordinator and 22-year program veteran.
Scanniello Peak is a peak named after Jeff Scanniello, surveyor at McMurdo and South Pole stations.
Uberuaga Island gets its name from Jules Uberuaga, long-time equipment operator.

A long journey for three little planes

Published in the Antarctic Sun

Nine people and three small planes recently arrived at McMurdo Station after a journey of over 11,000 miles (17,700 km) from Canada to spend four months flying in the Antarctic.

Each year, three de Havilland Twin Otter airplanes owned and operated by Kenn Borek Air travel from the company’s base in Calgary, Alberta, through North and South America and across Antarctica to support the U.S. and Italian programs on the Ice.

This year the planes left Calgary on Oct. 23 and flew to Boise, Idaho, where two were inspected before continuing on to Houston, Texas, where they spent the night before flying to Grand Cayman Island for the second night of the journey. The trip affords them a luxury they don’t have in Antarctica.

“Every night we go out for dinner and relax,” said Kenn Borek’s chief Antarctic pilot Sean Loutitt.

Leaving Grand Cayman, they flew the three planes over Panama and on past the Equator to Guayaquil, Ecuador.

Though government procedures in that area of the world can be difficult to deal with, three similarly-painted planes get friendly attention.

“They’re pretty smooth for us,” Loutitt said, though he noted that Ecuadorian officials inspect the planes carefully with drug dogs.

After a night in Ecuador, they leave the next morning for Arica, Chile, just over the border from Peru.

“We don’t land in Peru,” Loutitt said. “It’s hard to get landing permits.”

But they do just fine in Chile, with help from a few locals, including an air traffic controller who assists with paperwork.

“We seem to have built a good network of friends in Chile,” Loutitt said.

After a night in Arica, they normally fly halfway down the length of Chile to Puerto Montt.

This year the pilots were in a bit of a hurry to make it to McMurdo as soon as possible to start work. They continued to Punta Arenas, an extra 800 miles (1,200 km).

In Punta Arenas, they changed into their cold-weather clothes. They learned the weather was bad at Rothera, the British Antarctic Survey base on Adelaide Island, their next stop.

After a day’s layover, strong headwinds made what is normally a six-hour flight take eight hours. The winds, Loutitt said, included a 50 mph (80 kph) direct headwind, and crosswind gusts of over 80 mph (129 kph).

The gravel runway at Rothera is normally covered with snow in October, but this year it was not. Instead of just changing landing gear from wheels to skis on the snow-covered gravel runway, they had to shuttle planes one by one to a glacier runway for the conversion.

“Nine of us were working on this for 12 hours,” Loutitt said.

After Rothera, the usual flight path calls for the planes to refuel at Patriot Hills before continuing to the South Pole. This year, though, two of the three went directly to the Pole, while one
stopped at Patriot Hills to refuel and check the fuel cache the U.S. Antarctic Program maintains there.

All three made it to the Pole that day, Nov. 1, but then the weather came in.

“The next morning we woke up and couldn’t even see the airplanes,” Loutitt said.

Two days later the fliers were able to make it to McMurdo to begin the season’s work, which will include flying over 100 hours per month, supporting deep-field camps and aerial surveying
projects. One plane continued north to the Italian station at Terra Nova Bay.

At the end of the season, the planes will fly back to Canada again to work during the boreal summer before coming back down again next year.

“It’s a trek,” Loutitt said. “It’s actually kind of fun.”

Sunday, November 5, 2000

Cracking up: Sea ice under stress

Published in the Antarctic Sun

It’s strong enough to land planes on, too thick for a small drill to get through and cracks under pressure.

Sea ice is vital to the early-season research based at McMurdo Station.

Scientists base themselves on the frozen ocean to study the marine world. And when it breaks up and blows north, it leaves a spectacular expanse of open water.

David Cole and John Dempsey have forged a partnership out of the study of fracture of sea ice. Their work has involved lab work and field research in Alaska and now Antarctica.

Cole, from the U.S. Army Corps of Engineers Cold Regions Research and Engineering Lab, and Dempsey, from Clarkson University, are studying how ice behaves when under stress, in the breaking process.

Their project has faced some difficulty this year. The sea ice is thicker than usual, which is hard on their equipment.

They were expecting to find some ice as thin as 36 inches, and have equipment that can cut ice up to 84 inches, though very slowly. The thinnest they’ve found is 45 inches, with most of the ice 55 to 60 inches thick.

The amount of time required to cut through this thickness of ice is more than the team has.

“Because of ice thickness we can’t do the research we proposed,” Dempsey said. “We probably need a Ditch Witch,” a trenching machine for cutting through the ice faster.

Right now it takes too long to cut blocks the size they need. The biggest piece they’ve been able to study was three meters square. They would like to be studying deformation and fracture of blocks of sea ice up to 30 meters on a side, 100 times larger than they can get.

“The underlying theme of our research is to look at scale,” Dempsey said. Without large blocks of ice to study, they can’t get the data they would like.

Cole’s part of the study happens first. He wants to know how ice deforms when under stress. His work stops when the ice actually cracks, but the information he gathers helps Dempsey watch the right area of a floe when they do crack it.

“It starts with the microstructure,” Cole said.

The way ice crystals form and align themselves as the ocean freezes makes a difference in how the ice will crack, even months later. When there is a small current, ice crystals line up in one general direction.

That, in turn, makes the ice relatively weak in one direction, so it tends to crack for long distances in straight lines, Cole said.

“The properties are different depending on the direction,” Cole said. “It’s not just a homogeneous material.”

Some things are very different in the field from in the lab. For example, brine drains out of the ice when it’s brought into the lab, which changes the characteristics of the ice.

They have a camp about three miles (five km) from the ice edge, on fast ice. Their cutting area is a short distance away, but on much thinner, floating ice.

Cole and Dempsey and their two students mark out an area in which they want to work. They cut a block free of the ice sheet and then cut a starter crack, into which they insert a balloon-like loading device.

This “flat jack” has a computer-controlled inflation valve, which lets the team vary the pressure in the crack. The computer is set to stress the block of ice until they are ready to break it.

“We don’t want to accidentally break it,” Cole said.

As the ice deforms, they monitor it for stresses and tensions, as well as how it deforms in response to the pressure on the crack. Some of these processes, Cole said, vary with the size of the piece of ice, while others do not.

Eventually, though, they are ready to break the floe.

Ice breaking

“Ice fracture is a very complicated process,” Dempsey said.

They have learned that at the tip of a crack that is about to break further, a series of micro-cracks form. They have equipment listening for the noise of those tiny cracks, to warn them before the block actually breaks.

Cole always looks carefully at the structure of the ice as well as these micro-cracks, to estimate where the block will break.

“It’s nice to have nature verify your direction,” Cole said. But he’s never sure if he’ll be right until the chunk of ice opens up entirely,

“Until you come down and try to do some tests you don’t know,” Dempsey said. “There are so many different types of ice.”

The ice thickness affects the breakup, but the more significant factor is the nature of the ice itself, which depends on how old the ice is, how it formed, local landforms and other environmental factors.

“We’re getting different ice wherever we move,” Dempsey said.

The models Dempsey and Cole have made about the behavior of ice under tension are based on smaller, more homogeneous sections of ice. They are checking to see how well those models predict the behavior of the ice they find in McMurdo Sound, and in larger sections.

They’ve wrapped up for this season, but are ready to come back and keep working, perhaps with better equipment and ice conditions.

“We have two field seasons,” Cole said.