The LGM-30 A/B Minuteman I was an intercontinental-range, silo-based ballistic missile, and the first solid-fueled ICBM design developed by the United States and the forerunner of the Minuteman II and Minuteman III missiles.

Minuteman I Development

As the Cold War progressed and missiles became more numerous and advanced, U.S. defense planners recognized their ICBM arsenal was becoming increasing vulnerable. The limitations of liquid-fueled, gantry-launched missiles, such as Atlas and Titan I sparked fears that a Soviet first strike could potentially negate the U.S. ability to retaliate effectively. With this in mind, the U.S. Air Force began the bidding and development process for the Minuteman I in 1958.¹

For several reasons, the Minuteman I was America’s first modern ICBM. Chief among these was the missile’s use of solid fuel. Using solid fuel meant that the missile did not require fueling prior to launch, differentiating it from the Atlas and Titan I. This substantially reduced the time between receiving launch orders and the missile’s launch. Moreover, solid fuel is generally considered more reliable – solid-fuel engines are generally less complex, which reduces the number of failure points and simplifies maintenance. Furthermore, solid fuel is less volatile, does not leak, or require refrigeration. This stands in contrast to the liquid oxygen (LOX) and Aerozine fuels which caused several major accidents with missiles like the Atlas and Titan I.²

The Minuteman I was also notable for its lack of stabilization fins. Instead, it relied on internal stabilization mechanisms like vernier thrusters to maintain or adjust its course. Both solid fuel and internal stabilization methods have since become commonplace in the U.S. ICBM force.³

Minuteman I flight testing began in 1961 at Cape Canaveral, with the first launch characterized as “the most successful first flight recorded in the history of U.S. missile development.” After a relatively short test period of 21 launches, the missile entered service the following year.⁴

Specifications

The LGM-30A Minuteman-IA had a range of 10,000 km for its single Mark IV Reentry Vehicle (RV). This RV carried a single W-59 nuclear warhead which had a 1 MT yield. The system used an inertial guidance system with a pre-programmed digital computer. This accuracy was likely around 500-1,000 m CEP, given the accuracy of comparable systems of the time. The missile had a length of 16.45 m, a maximum body diameter of 1.88 m, and a launch weight of 29,500 kg. It had a three-stage solid propellant design. The LGM-30B Minuteman IB model was identical in all respects to the Minuteman IA except for an increased length of 17.0 m, slightly greater range, and use of the Mk. 11 RV.⁵

Service History

The Minuteman IA entered service in 1962 at Malmstrom Air Force Base (AFB) in Montana. The Minuteman IB entered service at four other bases, Ellsworth AFB in South Dakota, F.E. Warren AFB in Wyoming, Minot AFB in North Dakota, and Whiteman AFB in Missouri in 1963.⁶

The Minuteman was intended for large-scale deployment in order to deter nuclear attack by forcing the Soviets to expend its missiles targeting Minuteman I silos instead of civilian population centers.

Like other early ICBMs, the Minuteman I’s 1.5 km CEP would have made it largely ineffective against hardened military targets such as nuclear missile silos.⁷

Because of this, the missile was targeted against Soviet counter-value targets such as major industrial or population centers, in an effort to deter Soviet attacks against the United States.

Unlike the Atlas and Titan I which were developed for gantry launch, Minuteman I missiles were specifically designed from to be stored and launched from dispersed underground silos for protection. Fifty missile silos and five missile alert facilities (MAF) were assigned to each missile squadron.  Each MAF was responsible for controlling ten missiles, but for redundancy in event of failure, any of the five MAFs were able to control the entire squadron’s missiles.⁸

In June 1965, the U.S. Air Force began retiring the missile in favor of the LGM-30F Minuteman II. By this point, over 800 Minuteman I missiles had been produced. The final Minuteman Is were withdrawn from service in 1969.⁹

Following the missile’s retirement, a unique test flight was conducted in 1974 when a Minuteman I was air launched from a C-5 Galaxy in order to determine the viability of an air-based version of the MX Peacekeeper missile. While the test was successful, an air-based version of the MX was ultimately deemed extraneous.¹⁰