China's research vessel Xuelong, or "Snow Dragon," leaves the port of Qingdao Olympic Sailing Center for its fifth Arctic expedition in Qingdao, East China's Shandong province, July 2, 2012. Xuelong, an A-2 class icebreaker capable of breaking ice 1.2 meters thick, is estimated to travel over 17,000 nautical miles during its 90-day voyage. It is scheduled to return to Shanghai on Sept. 29. (Xinhua/Yu Fangping)

China's research vessel Xuelong, or "Snow Dragon," leaves the port of Qingdao Olympic Sailing Center for its fifth Arctic expedition in Qingdao, East China's Shandong province, July 2, 2012. Xuelong, an A-2 class icebreaker capable of breaking ice 1.2 meters thick, is estimated to travel over 17,000 nautical miles during its 90-day voyage. It is scheduled to return to Shanghai on Sept. 29. (Xinhua/Yu Fangping)