The use of high-altitude nuclear explosions to destroy satellites was considered after the tests of the first conventional missile systems in the 1960s. During the Hardtack Teak test in 1958 observers noted the damaging effects of the electromagnetic pulse (EMP) caused by the explosions on electronic equipment, and during the Starfish Prime test in 1962 the EMP from a warhead detonated over the Pacific damaged three satellites and also disrupted power transmission and communications across the Pacific. Further testing of weapons effects was carried out under the DOMINIC I series. An adapted version of the nuclear armed Nike Zeus was used for an ASAT from 1962. Codenamed "Mudflap", the missile was designated DM-15S and a single missile was deployed at the Kwajalein atoll until 1966 when the project was ended in favour of the USAF Thor-based Program 437 ASAT which was operational until 6 March 1975.