Lockheed built this unflown antiballistic missile (ABM) test vehicle for the U.S. Army's Homing Overlay Experiment (HOE). The HOE vehicle was designed to destroy a missile by physically impacting it - a concept known as "hit-to-kill." After separating from the booster, the vehicle would use its onboard sensors to identify and lock-on to the incoming missile and would use other components to direct it to impact. On the last of four HOE tests, a vehicle intercepted an incoming dummy warhead in the first successful demonstration of hit-to-kill technology in June 1984. The United States is now using much smaller hit-to-kill vehicles in deployed ABMs. Lockheed built this HOE test vehicle, and the U.S. Army transferred it to NASM in 1986.