Two months ago, Reuters photographer Lucas Jackson was invited to the 2011 Applied Physics Laboratory Ice Station, a temporary camp built out of plywood on Arctic sea ice. Far north of Prudhoe Bay, Alaska, the camp housed a couple dozen members of the British, Canadian, and U.S. navies and employees of the Applied Physics Laboratory. Jackson spent two days at the camp, watching its residents conduct tests on underwater and under-ice communications and sonar technologies. He kept his camera equipment warm and functional with chemical hand warmers whenever possible. Collected here are some chilly images from Jackson's trip to the far north last March.