More than Meets the Eye

The launch facility consists of three major below ground features: the launch tube, or silo, the launcher equipment room, and the launcher equipment building. These features were built to monitor and protect the missile while keeping it constantly ready to launch. The launch tube is 91 feet deep and approximately 12 feet across. Inside the launch tube, the nearly 60-foot-tall Minuteman missile was suspended above the bottom of the launch tube on the missile suspension system. The suspension system allowed the missile to absorb shock and provided a launch platform. The launcher equipment room is a two-story structure that surrounds the top portion of the launch tube and contains the electrical components that support and monitor the missile. It also houses the lithium batteries that provide backup power to the missile system if both commercial power and backup generator power fails. Its floors are suspended by shock isolators. Entrance to the launcher equipment room is gained through the 42-inch diameter personnel access shaft, which is closed and protected by two combination locks and a large steel plug. To gain access, the first combination lock, called the A circuit, is unlocked and removed from the security pit. Then the 2,700-pound primary door can be raised. Beneath the primary door is the secondary door, or B plug. Once a combination is successfully dialed into the top of the 14,000-pound B plug, it slowly lowers to the bottom of the personnel access shaft and permits access to the launcher equipment room. The launcher equipment building is buried beside the launcher and houses the backup diesel generator for use when commercial power fails and an environmental control system for the launch facility.

North Dakota · United States