The U.S. Navy began working with the Johns Hopkins University Applied Physics Laboratory (APL) in the early 1960s on a program called the basic point-defense missile system (BPDMS) to defend against the Soviet Navy’s Styx antiship missile. The Navy initially planned to adapt the U.S. Army’s MIM-46 Mauler system for use at sea, but after the Army canceled the program in 1964, the Navy turned its attention to the General Dynamics AIM-7E Sparrow air-to-air missile. (See “Armaments & Innovations,” December 2017, for more on the Sparrow’s development.) Redesignated as the RIM-7E Seasparrow, the missile became the main component of the Navy’s BPDMS.
The first version—essentially an unaltered AIM-7E—was fired from a Mk 25 box launcher, a modified Mk 16 antisubmarine rocket (ASRoc) launcher. It relied on semiactive radar homing for guidance, directed by a Mk 115 radar illuminator, which looked like two large searchlights. An operator followed voice commands from the sailors manning the ship’s search radar to aim the illuminator manually. The launcher would follow its motions automatically, so that the missile would see the signal reflected by the target.