Minuteman Missile
Historic Resource Study
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Section II — Life on the South Dakota Plains: Before, During, and After Minuteman

Chapter 4:
Chapter 4: Delta-01 and Delta-09 (1960s—80s) (continued)

Launch Facility Delta-09

Delta-09 is located approximately ten miles west-northwest of LCF Delta-01. It occupies part of an open, grassy tract of land straddling Pennington County Road T512, about 0.6 miles west and south of Interstate 90, Exit 116. Although the Interstate is visible in the distance, the site is in a rural area without other development around it. Historically under Air Force ownership, Delta-09 occupied ninety acres: eighty acres of concurrent use and ten acres of exclusive use, with one acre located within the security fence. Delta-09 is surrounded on the north, west, and south sides by the open land of Buffalo Gap National Grassland, under ownership of the United States Forest Service. In the distance are geological formations similar to those found in Badlands National Park. The launch structures are concentrated inside a rectangular area surrounded by a chain-link security fence. A double gate is located on the east side of the security fence. A gravel access drive leads from the double gate to the nearby county road.

The area inside the enclosure has been graded to form a level, earthen platform that is elevated a few feet above the surrounding terrain. The platform has a gravel surface, and was specifically planned to provide maneuver space for the truck-like transporter-erector vehicles that hauled and emplaced the Minuteman missiles. The missile launcher and LF support building are located near the southern end of the maneuver space platform, with most of their structural elements underground. A smaller rectangular area at the north end of the platform outlined by four, low, small concrete corner pylons served as a landing pad for helicopters. Floodlights mounted atop two wooden utility poles at opposite corners of the maneuver space provided illumination for nighttime maintenance activities at the site. Two remnants of the concrete-base pad from the earlier outer zone security system antennas remain at the site: a square concrete pad with four reflector mount pedestals is located to the southwest (rear) of the missile launcher and a clutter monument and footing of the antenna pedestal are located to the rear (south) of the launch support building.

Missile Launcher

The missile launcher 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 launcher consists of an underground launch tube (silo), surrounded by a cylindrical equipment room and covered by a hardened, ballistically actuated closure door. A heavily secured hatchway connected to the equipment room allowed Air Force personnel to enter the launcher and step down a metal rung ladder into the upper and lower equipment rooms surrounding the missile to conduct routine maintenance activities.

The launch tube is essentially a reinforced-concrete cylinder lined with a quarter-inch steel plate. It measures twenty-five feet in diameter (inside dimension) and approximately eighty feet deep. The tube rests atop a four-foot-thick, reinforced-concrete foundation, with its lower forty-six feet encased in approximately ten inches of heavily reinforced concrete. A two-inch-thick steel plate on the floor of the tube serves as a blast deflector for the missile's exhaust. [294]

Welded to the walls of the launch tube, about twenty-one feet above the floor, are pulley blocks for the three-point suspension system that supported the installation's Minuteman missile. The suspension system consists of a free-floating, steel missile-support ring attached to three wire cables. The cables pass over the pulley blocks and fasten to large, coil spring-type shock absorbers fixed to the base of 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 twenty-five feet by fifteen feet and twenty-eight feet deep, with a four-foot-thick slab foundation, and walls two feet thick. A six-inch-wide "rattle space" between the equipment room and the launch tube allows the two structures to move independently.

The lower level of the equipment room contains a motor generator and supports for twelve large storage batteries. The batteries themselves were removed from the missile launcher during deactivation in 1993. An electrical surge arrestor room is located on the southeast exterior wall of the lower level. The numerous surge arrestors inside were designed to prevent electronic equipment inside the launcher from being damaged by electromagnetic pulses resulting from nuclear explosions. On the south side of the lower level, the cylindrical ballistic actuator that opens the launcher closure door during the launch sequence stands upright and extends through the upper level floor.

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" (no longer in place) that was used to align the missile's guidance system. Directly above the bench is a canted cylindrical porthole (sight tube) glazed with bulletproof glass that is now permanently welded shut. This sight tube is aligned so as to point through the open access hatch, which allowed guidance technicians to establish visual references to a pair of azimuth markers (surveyors' benchmarks) located on the surface outside of the security fence. [295]

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 LCC, and conduct the countdown. 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. 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 sixty feet to the bottom of the silo.

The underground launch tube and equipment room are covered by a massive, reinforced-concrete roof slab, known as the launcher closure. The top of the slab is level with the surface of the maneuver area. The roof slab is roughly teardrop-shaped in plan, with its apex pointing toward the northwest. The reinforced-concrete closure door is three and one-half feet thick and weighs more than ninety tons. If a missile had been fired the launch enclosure would have been blown open with great force. A concrete approach apron on the north side of the launcher closure with steel transporter erector pylons and transporter erector jack pads was used to align and support the transporter erector while the missile was emplaced. Transporter erector landing gear pads are also located just north of the apron.

The area directly south of the missile launcher is approximately three and one-half 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, buttressed concrete wing wall on each side of the door opening separates the maneuver area from the ground below. A concrete track apron is directly behind the launcher closure with a center track rail and side closure or maintenance tracks. The launcher closure 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 shaped like the cowcatcher on a steam locomotive and is designed to clear debris from the tracks when the ballistic actuator flings the door aside. The grade slopes slightly south from the apron to provide drainage away from the launcher. If the missile or one of its major components had to be removed or replaced, maintenance workers would use a hydraulic pipe pusher mounted on a cogged rail in the middle of the track apron to jack the closure door open.

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, operated by two hydraulic cylinders. The door opens into a cylindrical shaft that descends to the lower level of the equipment room. Fitted into the shaft is the "B‑plug," a piston-like, steel security door operated by an electro-mechanical actuator. The silo cannot be entered until the B-plug is retracted.

Slight modifications have been made to Delta-09 to prepare it for interpretation as a static display. The launcher closure has been permanently fixated in a partially open position, in agreement with the START Treaty, and a glass and aluminum viewing enclosure was installed over the opening in 2001. A deactivated training missile was installed in the launch tube in 2001. The glass viewing enclosure allows visitors to see into the launcher to view the training missile. (For further discussion of Delta-09 modifications see Section III, Chapter 3: Minuteman Missile National Historic Site)

Launch Facility Support Building

Located adjacent to the missile launcher on the southeast is the 1963 LF support building, which contains an array of mechanical, electrical, and environmental equipment. This box-like underground structure has its roof about one foot above ground level. Constructed entirely of reinforced concrete, the building is rectangular in plan, measuring roughly sixteen feet wide, twenty-five feet long, and eleven feet deep. At the north end of the structure is a narrow rectangular areaway, covered with steel grating and a steel entry hatch. A ladder mounted on the interior wall provides access through the hatch down into the building. Two removable steel hatches in the middle of the roof of the support building allowed maintenance crews to quickly install large pieces of equipment or remove them for repairs.

The support building contains electrical distribution equipment; a diesel-fueled emergency generator that supplied electrical power when the commercial source was unavailable; a brine chiller unit that provided cold water to the launch equipment room air handler, which in turn, provided the electronic racks and launcher with temperature and humidity-controlled air; a hydraulic pump for the personnel access hatch; a temperature control air compressor; and various panels for mechanical, security, and communications systems.

Associated Structures

Delta-09 includes five structures historically associated with the launcher, two of which are antennae. The improved minuteman physical security system (IMPSS) antenna, a white fiberglass monopole, rises from the base of the roof slab on the east side of the closure-door opening. This antenna is part of the IMPSS that was installed at the launch site in 1989. IMPSS is a microprocessor-based surveillance system designed to detect outer zone intruders. It replaced troublesome older security systems so sensitive that they could be set off by "elk, rabbits, even high-jumping grasshoppers." [296] A hardened UHF antenna, installed c.1968 to link the LF with the SAC's airborne launch control center, is located a few feet to the northwest of the silo opening. It rests atop a thirteen-foot-diameter, reinforced-concrete base, shaped like an inverted saucer. The antenna itself is housed inside a cast-steel frustum capped with a conical, gray fiberglass weather dome.

Three other structures are located at Delta-09 outside the security fence. A cathodic protection rectifier installed in 1982-83 is located on the south side of the access drive, approximately 160 feet east of the security fence. Its aboveground portion consists of a galvanized steel electrical box mounted on a wood pole protected with a small fence. The below ground portion consists of a well approximately 220 feet deep, containing eleven graphite anodes. Two azimuth markers, used in conjunction with the autocollimator to align the Minuteman guidance system, are each located approximately one thousand feet from the launcher—one to the north-northwest and the other to the north-northeast. Each azimuth marker consists of a cylindrical concrete pylon, three feet in diameter and eight feet deep, set vertically into the ground. The visible portion of each pylon is approximately eighteen inches in diameter and four feet high. A disc-shaped aluminum alloy survey plate is set into the top of each pylon. Two HICS marker posts are located to the south of the chain link security fence. The wooden posts are about twelve feet tall with orange bands around the top and directional arrows to mark the location of the underground HICS.

Conversion to Minuteman II

Between 1971 and 1973, facilities at both the Delta-01 and Delta-09 sites were modified slightly when Ellsworth replaced its arsenal of Minuteman I missiles with the more advanced Minuteman II. The most important changes associated with this conversion were contained within the missiles themselves, since Minuteman II featured a more powerful propulsion system and a more accurate guidance system than its predecessor. Changes included installation of new electronic ground-support equipment in existing racks at both the LCF and the LF; and the installation of electronic filters, seals, and circuit-breaking equipment at both sites to protect the facilities against damage from the electromagnetic pulses released by atomic blasts. Because the Minuteman II was slightly longer than the Minuteman I, the missile support ring inside the LF silo was lowered by lengthening suspension cables. The optical alignment system was adapted to work with the new missile by welding stops to the autocollimator bench to limit the instrument's range of motion. The retractor mechanism for the umbilical cable was relocated, and several other cables and fluid lines within the Missile Launcher were rerouted. No structural changes were required at either the LF or the LCF to accommodate the new missile. [297]

After conversion to Minuteman II, Delta Flight experienced only minor modifications as it continued to fulfill its mission. Changes at the LCF support building included new steel siding and replacement windows, the addition of a women's latrine, air conditioning, and interior redecorating. Alterations to the LCC included the installation of carpet, Velcro-attached fabric acoustical ceiling panels, a curtained sleeping compartment (called a modular bed storage unit), an updated latrine, and a new privacy curtain to accommodate mixed gender crews.

Delta-01 and Delta-09 were among the remote facilities where the men and women of Ellsworth lived and worked. They were designed for security and functionality. They were designed, in the final analysis, for a function each hoped would never be needed. Let us now turn to those men and women, to their duties and their lives, and to the culture of the missileers and the missile crews.

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Last Updated: 19-Nov-2003