Nuclear submarine nuclear-powered submarine was first proposed in the United States Navy by the Naval Research Laboratory's Ross Gunn in 1939. Construction of the world's first nuclear powered submarine was made possible by the successful development of a nuclear propulsion plant by a group of scientists and engineers at the Naval Reactors Branch of the Bureau of Ships and the Atomic Energy Commission. In July 1951 the U.S. Congress authorized construction of the first nuclear-powered submarine, "Nautilus", under the leadership of Captain Hyman G. Rickover, USN (sharing names with Captain Nemo's fictional submarine in Jules Verne's "Twenty Thousand Leagues Under the Sea",
Hans Tausen Ice Cap Hans Tausen Ice Cap Hans Tausen Ice Cap () is an ice cap in northern Greenland. Ice cores show it is around 3500–4000 years old. It formed since the Holocene climatic optimum of 6000-8000 BP. The ice cap is about 100 km from north to south and 80 km from east to west and sits on a 1300 m high plateau. The Hans Tausen Ice Cap is the source of many glaciers, including Ymer Glacier, Lur Glacier and the Tjalfe Glacier. It is a well studied ice cap, and is important to understanding the last Climatic Optimum. (Holocene climatic optimum)