Ascension Island is an isolated volcanic island in the equatorial waters of the South Atlantic Ocean, around 1,600 kilometres (1,000 mi) from the coast of Africa and 2,250 kilometres (1,400 mi) from the coast of Brazil, which is roughly midway between the horn of South America and Africa. It is governed as part of the British Overseas Territory of Saint Helena, Ascension and Tristan da Cunha, of which the main island, Saint Helena, is around 1,300 kilometres (800 mi) to the southeast. The territory also includes the sparsely populated Tristan da Cunha archipelago, some 3,730 kilometres (2,300 mi) to the south, about halfway to the Antarctic Circle.
The island is named after the day of its recorded discovery, Ascension Day. It played a role as an important safe haven and coaling station to mariners and for commercial airliners during the days of international air travel by flying boats. During World War II it was an important naval and air station, especially providing antisubmarine ...
warfare bases in the Battle of the Atlantic. Ascension Island was garrisoned by the British Admiralty from 22 October 1815 to 1922.
The island is the location of RAF Ascension Island, which is a Royal Air Force station, a European Space Agency rocket tracking station, an Anglo-American signals intelligence facility and the BBC World Service Atlantic Relay Station. The island was used extensively by the British military during the Falklands War. Ascension Island hosts one of four ground antennas (others are on Kwajalein Island, Diego Garcia, and Cape Canaveral) that assist in the operation of the Global Positioning System (GPS) navigational system. The National Aeronautics and Space Administration operates a Meter Class Autonomous Telescope (MCAT) on Ascension Island for tracking orbital debris, which is potentially hazardous to operating spacecraft and astronauts, at a facility called the John Africano NASA/AFRL Orbital Debris Observatory.