is believed to have contained alternating layers of zirconium "staples" embedded in nitrocellulose powder, followed by gelatinizing with nitroglycerine, thus forming a higher thrust double-base powder. The Sprint was controlled by ground-based radio command guidance, which tracked the incoming reentry vehicles with phased array radar and guided the missile to its target. The Sprint was armed with an enhanced radiation nuclear warhead with a yield reportedly of a few kilotons, though the exact number has not been declassified. The warhead was intended to destroy the incoming reentry vehicle primarily by neutron flux. The first test of the Sprint missile took place at White Sands Missile Range on 17 November 1965. Design predecessors The "HIBEX" (HIgh Boost EXperiment) missile is considered to be somewhat of a design predecessor and competitor to the Sprint missile, as it was a similar high-acceleration missile in the early 1960s, with a technological transfer from that program to the Sprint development program occurring. Both were tested at the White Sands Launch Complex 38. Although HIBEX's initial acceleration rate was higher, at near 400 g, its role was to intercept reentry vehicles at a much lower altitude than Sprint, , and it is considered to be a last-ditch anti-ballistic missile "in a similar vein to Sprint". HIBEX employed a star-grain "composite modified double-base propellant", known as FDN-80, created from the mixing of ammonium perchlorate, aluminum, and double-base smokeless powder, with zirconium staples ( in length) embedded or "randomly dispersed" throughout the matrix. The British "Thunderbird" rocket of 1947 produced an acceleration of 100 g with a polysulfide composite propellant, star-grained cross-section solid rocket motor. Testing The first test of the Sprint missile took place at White Sands Missile Range on 17 November 1965. Survivors The Air Defense Artillery museum at Fort Sill, Oklahoma has both Safeguard missiles (Sprint and Spartan), plus Nike Zeus and HIBEX on exhibit. The White Sands Missile Range Museum has a HIBEX on exhibit. Remote Site Launch Sprint Missile Historic Museum, RSL #3 Missile Site, Cavalier, North Dakota (Full Scale Replica on Display) Gallery See also 53T6 Anti-ballistic missile Surface-to-air missile LIM-49 Spartan MIM-14 Nike Hercules Project Nike Safeguard Program References Further reading External links Sprint Directory of U.S. Military Rockets and Missiles Terminal defense using the Sprint Sprint missile launch Nike Sprint dual launch during a salvo test at Kwajalein Atoll test range Video of Nike Sprint launch (2 MB .mpg) Encyclopedia