Medical plane on daring rescue mission lands at South Pole The South Pole Telescope and the BICEP Telescope at Amundsen-Scott South Pole Station in August 2008. (REUTERS/Keith Vanderlinde/National Science Foundation/Handout) A small plane landed at the South Pole Tuesday afternoon to extract at least one sick worker from a U.S. scientific research station. A Canadian Twin Otter plane made the 1,500-mile, nine-hour trip from a British base on the Antarctic peninsula. The National Science Foundation (NSF), which runs the Amundsen-Scott polar station, said the flight crew will rest for 10 hours, then depart for the British station before traveling on to a hospital ouitside Antarctica. The unidentified individual's illness or condition has not been disclosed, but the NSF said the worker is an employee of Lockheed Martin, which provides logistical support. Spokesman Peter West added that two station workers are ill and officials were still trying to decide whether to evacuate both or just the sickest one. Monday was the first day of winter in the Southern Hemisphere -- the sun will not rise at the South Pole till the first day of spring in September. The temperature Tuesday morning at the South Pole station was minus 75 degrees, according to Weather Underground. The latest mission is pushing the limits of what is acceptable, Tim Stockings, operations director at the British Antarctic Survey in London, told the Associated Press. "The air and Antarctica are unforgiving environments and punishes any slackness very hard," Stockings said. "If you are complacent it will bite you." The danger is the dark, the cold and the weather, Stockings and West said. Cold affects a lot of things on planes, including fuel, which needs to be warmed before takeoff, batteries and hydraulics, West said. The Twin Otter can fly in temperatures as low as minus 103 degrees, he said. A second turboprop is being held in reserve on the ice-covered runway at the British Rothera station in case something goes wrong with the rescue attempt. There have been three emergency evacuations from the Amundsen-Scott station since 1999. The first such flight rescued the station's doctor, Jerri Nielsen, who had breast cancer and had been treating herself. Rescues were done in 2001 and 2003, both for gallbladder problems. The NSF decided last week to mount the rescue operation because the staffer needed medical care that can't be provided there. The station has a doctor, a physician's assistant and is connected to doctors in the U.S. for consults, West said. There are 48 people -- 39 men and 9 women -- at the station, West said. The Associated Press contributed to this report.