In a rare and difficult mission, a plane successfully rescued two sick workers from the U.S. science station at the South Pole Wednesday. The medical rescue took place in the dark. Regular flights to the South Pole are usually considered too risky between the months of February and October. The Amundsen-Scott station is run by the National Science Foundation. The plane arrived there after a difficult 2,400-kilometer, nine-hour trip from a British base on the Antarctic Peninsula. NSF spokesman Peter West told VOA the rescue operation went according to plan. “It was a very challenging operation for the pilots, for everyone who is around to support the pilots, everyone from weather forecasters, to flight followers, all those people. So it was extremely challenging and they have performed exceedingly well in the face of those challenges.” The National Science Foundation did not release the workers’ names, nationalities, or medical conditions. The NSF decided last week to evacuate at least one person from the station.