Missile Sprint

The system originated from research into the interception of ballistic missiles during atmospheric reentry. Early anti-ballistic missile designs were vulnerable to radar decoys and high-altitude nuclear bursts that obscured sensor data. By delaying interception until reentry vehicles descended into the lower atmosphere, atmospheric drag separated decoys from actual warheads. This operational profile required a high-acceleration interceptor capable of engaging targets within seconds. The development transitioned through the Nike-X and Sentinel programs before integration into the Safeguard program.

The missile is a two-stage, solid-fuel interceptor designed for silo-based deployment. Launch is initiated by an explosive-driven piston that ejects the airframe through a fiberglass cover. The first-stage motor utilizes a double-base propellant with embedded zirconium staples to achieve high thrust. The missile accelerates at 100g, reaching a speed of Mach 10 within five seconds. During flight, the airframe reaches velocities that generate skin temperatures up to 6,200°F, requiring an ablative shield for thermal protection. The resulting plasma sheath necessitates high-power radio signals for the ground-based radio command guidance system, which uses phased array radar to track targets and provide steering commands via a deflectable nose cone.

The system is armed with a W66 enhanced-radiation thermonuclear warhead with a low-kiloton yield. This warhead is designed to neutralize incoming reentry vehicles primarily through neutron flux. A secondary version of the missile was researched to feature improved guidance systems and increased resistance to nuclear effects for the protection of hardened missile fields.

The United States Army was the sole operator of the system. It reached operational status in 1975 as part of the Safeguard program, specifically tasked with the defense of Minuteman intercontinental ballistic missile silos. The system was deactivated in 1976 after a brief service period. This decommissioning was driven by high operational costs and the introduction of MIRV technology, which affected the system's technical and economic efficacy. There are no recorded instances of combat use.