Capt. Graydon Muller, pilot with the 6th Special Operations Squadron, Hurlburt Field, Fla., skis down from the summit of Australia's highest mountain, Mount Kosciuszko, with the American flag flying overhead, Oct. 3, 2011. This was part of the U.S. Air Force 7 Summits Challenge, where a group of Airmen have made the goal of climbing to the top of each continent's highest mountain. (Courtesy photograph)