Delta-09 Audio Described Tour

Minuteman Missile National Historic Site


Outside the Silo introduction The silo is covered by a massive, reinforced-concrete roof slab, known as the launcher closure. The top of the slab is level with the surface. The reinforced-concrete closure door is 3 1/2 feet thick and weighs more than 80 tons. There is a concrete approach apron on the north side of the launcher closure with steel transporter erector pylons and transporter erector jack pads to align and support the transporter erector when emplacing the missile.

The area directly south of the missile launcher is approximately 3 1/2 feet lower than the gravel maneuver area, exposing the south edge of the roof slab. Cast into the southern edge of the roof slab is a pocket-like opening for the launcher's horizontally sliding closure door. A low concrete wingwall on each side of the door opening separates the main part of the compound from the ground below. A concrete track apron is directly behind the closure door. A center track rail extends to the south and was used to manually open and close the closure door. The closure door rolls open on two wide steel tracks mounted atop deep reinforced-concrete beams cantilevered out from the launcher. The closure door's steel-sheathed leading edge is designed to clear debris from the tracks when the ballistic actuator flings the door aside.

Outside the Silo Delta-09 was designed to serve as a temperature- and humidity-controlled, long-term storage container, protective enclosure, support facility, and launch pad for a Minuteman ICBM. The silo consists of an underground launch tube that is surrounded by a cylindrical equipment room and covered by a hardened closure door. A heavily secured hatchway connected to the equipment room allowed Air Force personnel to enter the launcher for routine maintenance activities. For more routine maintenance activities, workers entered the silo through the personnel access hatch in the northeast corner of the roof slab. The access hatch is a heavily reinforced steel-and-concrete vault door that is operated by two hydraulic cylinders. The door opens into a cylindrical shaft that descends to the lower level of the equipment room.

Entering the silo Encircling the upper portion of the launch tube is a cylindrical, two-level equipment room, built of heavily reinforced concrete with a steel liner. The equipment room is about 30 feet in diameter and 28 feet deep. It has a 4-foot-thick slab foundation and 2-foot-thick walls. A 6-inch-wide "rattle space" between the equipment room and the launch tube allows the two structures to move independently.

Top Deck 01 Mounted on the wall adjacent to the equipment racks are two cylindrical, stainless-steel chemical tanks. These tanks originally contained a sodium chromate solution for cooling the Minuteman missile's guidance system.

Top Deck 02 The upper level of the equipment room consists of a steel-framed platform covered with a rolled-steel deck plate. Cast into the east outer wall is a narrow steel-faced bench, calibrated with compass bearings. Part of a complex optical alignment system, the bench originally supported an "autocollimator" that was used to align the missile's guidance system. Directly above the bench is a canted cylindrical sight tube glazed with bulletproof glass. The sight tube is aligned so as to point through the open access hatch. This allowed guidance technicians to establish visual references to a pair of azimuth markers located on the surface outside of the security fence. The sight tube is now permanently welded shut.

Top Deck 03 The northwest one-third of the upper-level floor is suspended from a series of coil-spring shock struts attached to the ceiling. Attached to the shock-mounted floor are racks of electronic equipment used to monitor and troubleshoot the missile, communicate with the Launch Control Center, and conduct the countdown.

Upper Deck Maintenance workers could gain access to the missile and the bottom of the silo by removing the hatch plates from the side of the launch tube, lowering the access door or "diving board," and installing a motorized cage. The two-person work cage could reach the circumference of the launch tube and also could lower workers 60 feet to the bottom of the silo.

Diving Board View The launch tube is essentially a reinforced concrete cylinder lined with a 1/4-inch steel plate. It is 12 feet in diameter and 80 feet deep. A 2-inch-thick steel plate on the floor of the tube serves as a blast deflector for the missile's exhaust.

Slight modifications have been made to Delta-09 to prepare it for interpretation as a static display. The launcher closure has been permanently fixed in a partially open position and a glass viewing enclosure was installed over the opening in 2002. The glass and aluminum viewing enclosure is a domed structure over the opening of the missile launcher. The training missile was placed in the launch tube in 2001.


An audio described tour of the Delta-09 missile silo. The only sound is a description of the rooms with basic context of what you see. A written transcript is available.


4 minutes, 53 seconds


NPS/Minuteman Missile National Historic Site

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