The Supersonic Low Altitude Missile or SLAM was a U.S. Air Force nuclear weapons project conceived around 1955, and cancelled in 1964. SLAMs were conceived of as unmanned nuclear-powered ramjets capable of delivering thermonuclear warheads deep into enemy territory. The development of ICBMs in the 1950s rendered the concept of SLAMs obsolete. Advances in defensive ground radar also made the stratagem of low-altitude evasion ineffective. Although it never proceeded beyond the initial design and testing phase before being declared obsolete, the design contained several radical innovations as a nuclear delivery system. Conceived role The SLAM was designed to complement the doctrine of mutually assured destruction and as a possible replacement for, or augment to, the Strategic Air Command system. In the event of nuclear war it was intended to fly below the cover of enemy radar at supersonic speeds and deliver thermonuclear warheads to roughly 16 targets. Innovations The use of a nuclear engine in the airframe promised to give the missile staggering and unprecedented low-altitude range, estimated to be roughly (over 4.5 times the equatorial circumference of the Earth). Despite misinformed public opinion, the idea that the engine could act as a secondary weapon for the missile is not practical. According to Dr. Theodore C. Merkle, the head of Project Pluto, in both his testimony to Congress and in a publication regarding the nuclear ramjet propulsion system, he reassures both Congress and the public of this fact. Specifically, he states "The reactor radiations, while intense, do not lead to problems with personnel who happen to be under such a power plant passing overhead at flight speed even for very low altitudes." In both documents, he describes calculations that prove the safety of the reactor and its negligible release of fission products compared to the background. Along the same vein of these calculations, the missile would be moving too quickly to expose any living things to prolonged radiation needed to induce radiation sickness. This is due to the relatively low population of neutrons that would make it to the ground per kilometer, for a vehicle traveling at several hundred meters per second. Any radioactive fuel elements within the reactor itself would be contained and not stripped by the air to reach the ground. Another revolutionary aspect of the SLAM was its reliance on automation. It would have the mission of a long-range bomber, but would be completely unmanned: accepting radioed