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Spotlight

Southern Adventures

Paul Callaghan

This coming winter won't seem so cold to me, after I spent two months of the last summer in the Ross Sea region of Antarctica accompanied by my friend and colleague Craig Eccles. We were there as part of the New Zealand Sea Ice research programme, a collaboration between four universities and Industrial Research Ltd. Our mission was to carry out a nuclear magnetic resonance (NMR) investigation of the unfrozen brine water in the sea ice of McMurdo sound.

The first task that prospective Antarctic researchers have to undertake is to be trained, entailing a week spent at Lake Tekapo riding in Iroquois helicopters, and learning about firefighting, radio communications, first aid, crevasse extraction methods, use of polar tents and cookers, use of Antarctic clothing, survival techniques and ice and snow skills.

After the initial training come the medical checks. The New Zealand Antarctic Programme requires an embarrassingly thorough medical examination, along with a complete range of blood tests and dental certification.

Then came the rush to get the equipment ready. This involved building an NMR spectrometer which, instead of needing a special magnet, utilised the highly uniform (and free!) magnetic field of the Earth. This field has a value of around 65 microTeslas in the Antarctic, compared with the usual 1-7 Teslas of the laboratory magnets at Massey University.

NMR is able to discriminate signals arising from nuclei hosted by molecules in the solid state from those in a liquid state. The objective of the present project is to use this selective sensitivity to examine the state of the brine water component of sea ice. In particular we hope to measure brine water volume fractions and brine water mobility.

The trip south takes five hours in a US Air Force C-141 (Starlifter). We sat in webbing seats in full cold weather survival gear, with earplugs to keep out the engine noise and a pre-issued snack bag to help pass the time. Landing on the sea ice runway is much like any other landing, but to climb out the hatch and see Hut Point Peninsula, Observation Hill, Cape Armitage and Mounts Erebus and Terror is a unique thrill. Our other vivid experience was meeting -20oC and a stiff breeze.

The first three days were spent at Scott Base, where we had to undergo further Antarctic field training (AFT). Our very patient and helpful instructor was Tarn Pilkington, a mountaineer and search and rescue (SAR) expert from Mt Cook. Tarn had us drilling sea ice cracks, pitching survival tents, learning further crampon and ice axe skills, crossing crevasses and building a survival shelter. He also introduced us to the use of hand-held Global Positioning Systems (GPS) which are now routine equipment in the Antarctic. As part of our final training we slept in our home-built ice trench on the Ross Ice Shelf, waking to -30oC temperatures and a heavy dusting of ice on our faces.

Away to Camp

Finally we were ready to be transported, via Hagglunds tracked vehicle, to our field camp 20 kilometres away near Cape Evans. In October all of McMurdo Sound is frozen far to the north, and we travelled the entire journey on a two-metre crust above hundreds of feet of ocean. Our gear was placed in a ski trailer and bumped its way across the frozen sea. Near Inaccessible Island we met the remaining four members of our party who had been making their sea ice measurements for the past fortnight.

After a warm welcome from our companions, we headed off again in the Hagglunds to take advantage of a unique opportunity to visit the historic huts close by at Cape Evans and at Cape Royds, some 10 kilometres further to the north. Evans was the base of Scott's ill-fated 1910-1912 Terra Nova expedition while Royds was Shackleton's base from 1908 to 1909. These huts, which are under the care of the New Zealand authorities, provided an opportunity to step back in time to the heroic era. They made a deep impression on us both.

At Cape Royds, the Adelie penguins were streaming south in ones and twos to meet their mates at the Cape Royds rookery. We were very fortunate to be there at that time. Only one week before there had been just five penguins. Now there were hundreds and the mating had begun! The area is awesomely beautiful. Across McMurdo Sound is the Royal Society Range through which the Ferrar and Blue glaciers carry their vast streams of ice down from the Polar plateau. South, the horizon is dominated by Mount Discovery, while down the coast towards Evans are the towering blue cliffs of the Barne Glacier. Immediately behind us to the East and omnipresent during our visit, was Mount Erebus, rising 13,500 feet straight from the sea.

Back at Inaccessible Island we began work assembling our gear. Our probehead we placed in a snow cave, while the electronics were placed in a nearby polar tent. After initial teething problems caused by low-temperature effects on electronic connections, we were operating. Core samples were extracted at 200 mm intervals from the surface to the sea at a depth of 1.9m, using the special auger provided by our IRL colleagues.

Electrical conductivity measurements were also made on these samples by Dr Pat Langhorne of Otago University to gain an estimation of salinity. The results we obtained show that strong correlations exist between the NMR data and the salinity/temperature profiles. They are certainly sufficiently encouraging to justify more visits!

Good Points and Bad Points...

Field camp was simple and, at times, rigorous. We slept in a polar tent in temperatures from -25oC to -8oC. Our four-layer sleeping bag and four layers of clothing kept us warm in bed, provided we wore our woollen head covering. Getting up required that we put on two or three more layers of survival gear, first bashing it out of its frozen shapes so that we could enter it.

Still, camp life had its pleasant side, with regular visits from penguins, excursions to seals at nearby tide cracks, good fellowship with our companions at meals and coffee breaks and no restrictions on our consumption of chocolate. We worked under the midnight sun, eating and sleeping when we felt like it. This led to breakfast at 1 pm, dinner at 1 am and climbing excursions up Inaccessible Island at 3 am. When the blizzard hit us we were ready for sleep.

Sleeping in a polar tent in a 40-knot gale at -15oC is an experience. It is a little terrifying at times but it certainly helps register a few priorities. When our instrument case broke its guy lines and went into orbit over Antarctica we were just grateful that it wasn't us. After three days of raging winds, a break occurred and the D5 bulldozer from Scott Base along with a Hagglunds and guiding skidoo was able to make it to our camp to tow us back.

That evening we collapsed in our beds at Scott Base, exhausted from our adventures and glad to be sleeping on a mattress rather than on the snow surface of the Cape Evans sea ice. At midnight, with the sun at its lowest point in the south over Minna Bluff, the outside air was at last still and the ice slopes of Ross Island gleamed blue and gold.

On a final climb up Observation Hill the boundary between the Ross Ice Shelf and the sea ice was clearly marked in the glancing illumination, and the pressure ridges near Pram Point stood out sharply in the shadows of the midnight sun.

To stand on the top of Observation Hill gives pause for thought. One cannot escape the presence of Scott's companions who climbed there so many years ago each evening in March 1912, hoping to catch a glimpse of the returning party from the Pole. The cross placed there by Cherry-Garrard and Atkinson still bears the quote from Tennyson's Ulysses, "To strive, to seek, to find, and not to yield".

The next day, after a visit to the 1902 Discovery we were on our way back to Christchurch. Two weeks in Antarctica had left their mark. It would be a week before the tips of our fingers regained their normal feeling, but it will be a lifetime before we lose a desire to return to that beautiful and dramatic wilderness.

Professor Paul Callaghan is in Massey University's Physics Department.