Engineers aboard the Coast Guard Cutter Polar Star replace a shaft seal while in the Ross Sea near Antarctica on Tuesday, Jan. 16, 2018. The crew of the Seattle-based Polar Star is on deployment to Antarctica in support of Operation Deep Freeze 2018, the U.S. military’s contribution to the National Science Foundation-managed U.S. Antarctic Program. U.S. Coast Guard photo by Chief Petty Officer Nick Ameen.