<i>John Henzell</i><b> explains how researchers wintering at the world's most southerly settlement live for months in otherworldly conditions of isolation, bone-chilling temperatures and no sunlight, but they do have the chance to join on.</b> While the UAE bakes in the heat of summer, the residents of one of the coldest places on the planet are hoping for a cold snap so they can join one of the world's most exclusive clubs. The site of the United States research base, on a 3km-thick ice sheet at the geographic South Pole, is perpetually frozen, with temperatures at the height of summer averaging -25C. Now in the depths of the southern winter, four months after the sun set and still two months before it is due to reappear, the mercury hovers around -60°C. But some among the 43 research and support staff spending the 2009 winter at the Amundsen-Scott South Pole Station are hoping it will get even colder. If the outside temperature reaches -73.3°C, the psychological -100° level in Fahrenheit, the base's sauna is cranked into action, and the word goes around for those who want to join what is dubbed the 300 Club. Darryn Schneider, an Australian computer-systems engineer who joined the club nearly 10 years ago, describes membership as "one of those rare chances in life to do something really dumb. The concept is simple enough - a 300° change in temperature. This is accomplished by going into the sauna and cranking it up to 200°F, and then going outside when the official meteorology office thermometer is registering below -100°F." One of the technicalities of membership is that this is done while barely clad, relying on the low conductivity of super-dry air at the South Pole to allow the extremes of temperature to be bearable. Another member, English astrophysicist Simon Hart, says the 300 Club is "possibly the most exclusive club on earth; certainly it is one of the stupidest". He felt warm for about half of the journey from the sauna out to the ceremonial South Pole marker, but had not towelled off the sweat as he left the sauna. About halfway, he felt the sweat on his back began to freeze. By the time he reached the marker, his lungs were in agony from freezer burn. "I could feel the flesh on my shoulders, now frozen solid, crack as I moved," he recalls. "My fingers were getting the telltale numbness of frostbite. I knew the next 100 yards was going to hurt. "Back in the sauna, the air was filled with the sounds of cheering and coughing. Most people, even those wearing face masks, had frosted their lungs. For the next half hour as we warmed ourselves in the sauna, I broke into convulsive body-shaking fits of coughing. It was very unpleasant, but between coughing fits we were patting each other on the back, giving high fives, comparing our experiences, and vowing 'never again'." Even without joining the 300 Club, just spending a winter at the South Pole already qualifies people to be part of a spectacularly exclusive group. Only one thousandth of one per cent of the world's population will ever visit Antarctica, and only a tiny fraction of those will make it to the South Pole. Most of those will be in the summer, when the base population reaches 125. Wintering at the South Pole, with the bone-chilling cold outside, the perpetual darkness and the knowledge that no matter what happens, they are isolated at the bottom of the world for eight months, is more exclusive again. To put it into perspective, three times as many people have climbed Mount Everest than have spent a winter at the South Pole. The Antarctic historian Bill Spindler, who spent the winter of 1977 as manager of the South Pole station, says the 300 Club is believed to have originated in the late 1950s at a now-abandoned United States Antarctic base on the Ross Ice Shelf. "They had cold temperatures, but not -100F. But they did have a very hot sauna. On cold winter days they would crank it up to 250°F, or whatever was needed to get a 300° difference between it and the ambient temperature." The original South Pole base had a steam bath rather than a sauna. The human body is less able to tolerate wet heat, so it was impossible to raise the temperature to 200°F. Instead they had a 250-degree club, but when a new South Pole station was built in the mid-1970s as a striking geodesic dome, they made sure the design featured a sauna. (The dome was decommissioned in 2008 when the current building was officially dedicated.) "The 300 Club started with the first winter in the new station," Spindler adds, "and of course we did it in 1977." The club, with its defiant embrace of the conditions, serves as a counterpoint to the mental torpor, sleeplessness and emotional tetchiness that comes from six months without sunlight. The medical term for the physiological responses to the absence of light is Polar T3 syndrome. The residents at the pole have their own term for it: toasty. For Genevieve Ellison, one of 43 staff spending the 2009 southern winter at the South Pole, the 24-hour darkness has a disorientating impact on sleep patterns and consciousness, producing vivid dreams she finds herself convinced are real. "Sleep is easily disrupted, elusive and heavy-handed. This winter state of mind, this forever darkness, is numbing my mind, dulling my ability to retrieve words and ideas," she says. "I am losing nouns, playing a game of charades with co-workers in my efforts to fetch back the lost. Worse yet, I am losing their names sometimes. I am not alone in this. I have... stuttered to a halt as I approached the gone name, staring blankly in hope my conversation partner will pick it up by context. "The exclusivity of our club lends itself to a feeling of withdrawal from the outside world, where so few understand this experience. Even those past 'winter-overs', or those who have wintered on other stations, do not understand." In previous years, there would be 60 or 70 people spending the winter at the South Pole, but numbers have dwindled to the few dozen there now. This creates its own dynamic in a community where no one can escape from anyone else: planes cannot fly once the temperature hits -50°C, so they are effectively stuck there from when the last flight leaves in February until the next arrives in October. Among all the research into neutrinos, the ozone hole and astrophysics being conducted at the base, those 43 researchers and support workers are themselves the subject of study in preparation for the day when humanity embarks on long-distance space travel or creates a permanent moon base. The Antarctic bases that are populated through the winter are examples of what social psychologists dub ICE - Isolated and Confined Environments - and the South Pole base is about as isolated and confined as it is possible to be. The similarities with space travel go further than just being stuck somewhere with a nasty exterior environment. The Antarctic bases are atypical communities, where everyone works, where there are no elderly or infant residents, and where people will be there for one year then gone the next. There is also what is called the "personality paradox" of ICE postings because the jobs appeal to thrill-seeking, independent and adventurous types but the actual work involves routine tasks in a monotonous and restricted environment. The toll can be profound. The annals of Antarctic history include one disgruntled winter-overer at an Argentine base who set it alight, an irrational act that led to him having to spend the rest of his posting living with his deeply unimpressed colleagues in the base's far more cramped emergency shelter. At McMurdo Station, another American research station on the coast of Antarctica south of New Zealand, one of the workers attacked his supervisor with a hammer and had to be restrained by others then imprisoned in a hastily secured spare room at the station until FBI agents could be transported to Antarctica and take him to the United States for trial. All prospective workers at the United States Antarctic bases in winter have to take psychometric tests to assess their psychological suitability. New Zealand, which has a small year-round base near McMurdo Station, uses a less scientific assessment, based in part on what they call the "tent test": whether being stuck in a small tent in a blizzard for several hours with the prospective winter worker would send the other person fleeing into the storm or enjoying the one-on-one experience. And for all the training and testing, being at the South Pole means the chance of being confronted with events that are devastating and unexpected, prompting united displays by the community. At the South Pole base in the winter of 2000, one of the workers, the Australian astrophysicist Rodney Marks, died suddenly of a mysterious illness that was later determined to be methanol poisoning. Schneider, his compatriot, says the community decided that storing his body on the small and crowded base for repatriation in nearly six months time was deemed to be not respectful enough so in the weeks after his death in May, the base staff combined to manufacture every component of a "magnificent casket". Once it was ready, the burial service was announced. "No public announcement was made," he says. "Everyone was told personally." Every member of the base accompanied their colleague's casket as it was hauled on an old-fashioned Antarctic sled to the burial site, located in a direct line between the South Pole marker and Dr Marks's hometown in Australia, where it lay for nearly six months before being flown to New Zealand for an autopsy. And in the same week as Dr Marks's temporary burial, the temperature dipped below -73°C, and Schneider and others at the base had their chance to join the 300 Club.