Minuteman Launch Facility S-06 (Sierra-06 LF), Hawk Springs Wyoming

S-06 sat close enough to Hawk Springs to look ordinary on a local map, but it belonged to one of the least ordinary weapons deployments in the Cold War. What appeared from the road as a fenced launch-facility compound in Goshen County was, by the late 1980s, part of the only operational Peacekeeper ICBM field the United States ever built: a converted Minuteman silo tied to Sierra Flight and controlled from S-01.

Launch Facility S-06 was an unmanned missile launch facility assigned to Sierra Flight in the F.E. Warren Air Force Base missile field. Its parent control site was the S-01 Missile Alert Facility / Launch Control Center. The site code is S-06.

S-06 belonged to the 400th Strategic Missile Squadron during the Strategic Air Command era and later to the 400th Missile Squadron lineage in the 90th Missile Wing. It began as part of F.E. Warren's LGM-30B Minuteman I force, was later part of the base's LGM-30G Minuteman III field, and then was converted for the LGM-118A Peacekeeper missile. It is no longer an active missile site. The Peacekeeper strategic-alert mission ended on 2005-09-19, when the Air Force announced that no Peacekeeper ICBMs remained on strategic alert in the 400th Missile Squadron.

S-06 was one of ten launch facilities assigned to S-01 and Sierra Flight. Sierra Flight spread across rural southeastern Wyoming, with its launch facilities positioned around Yoder, Lyman, Hawk Springs, Huntley, and nearby Goshen County countryside. This dispersion was the heart of the Minuteman and Peacekeeper basing concept. The launch facilities were placed far enough apart that one strike could not eliminate the whole flight, and the crewed launch control center was separated from the missiles it monitored.

The immediate setting of S-06 is rural Goshen County, near Hawk Springs and south-southeast of Yoder. The site lies in the agricultural and ranching landscape of the Goshen Hole area, where missile infrastructure intersected with county roads, stock water, irrigation, rail corridors, and farm and ranch parcels. That landscape matters because F.E. Warren's missile field was not a fenced block of government land around the main base. It was a dispersed military system laid into ordinary civilian geography.

The 2000 Final Environmental Impact Statement for Peacekeeper Missile System Deactivation and Dismantlement places S-06 within the Goshen Hole Lowlands. The EIS describes the Goshen Hole as a wedge-shaped widening of the North Platte River system formed as softer sedimentary rock in the Brule-Arikaree Formation eroded down toward harder underlying formations. The EIS lists S-06 among the Peacekeeper launch facilities located in that lowland setting. It also notes that S-06 is in the Lance Formation, a Cretaceous unit with sandstone beds within shale and siltstone layers that can yield water to domestic and stock wells in southern Goshen County.

A typical launch facility in the former Peacekeeper group consisted of a launcher and launch facility support building inside a security fence. The 2013 Final Environmental Assessment for Minuteman III and Peacekeeper Silo Elimination states that Peacekeeper launch-facility sites averaged approximately 1.6 acres, with an interior about 90 feet deep, a 28-foot headworks section, and a 12-foot-diameter launch tube below the headworks.

A secondary public photo source provides S-06-specific field imagery of the site.

The Peacekeeper system was retired after the Cold War as U.S. strategic-force requirements changed and arms-control limits reduced the role of multiple-warhead ICBMs. Air Force public reporting stated that the Peacekeeper mission ended at F.E. Warren on 2005-09-19. At the deactivation ceremony, a missile combat crew officer at Papa-01 confirmed that no Peacekeeper ICBMs remained on strategic alert in the 400th Missile Squadron.

The 2013 Final Environmental Assessment for Minuteman III and Peacekeeper Silo Elimination gives the best public description of what happened to former Peacekeeper launch facilities such as S-06 after missile retirement. The assessment states that Peacekeeper missiles within the former 400th Missile Squadron had been removed, that previous deactivation activities included removal of missiles and salvageable items, that fluids had been drained from fueling, coolant, and hydraulic systems, and that electrical filters, switches, and power-supply batteries had been removed. After deactivation, gates were secured and each launch facility was placed in caretaker status.

New START then shaped the physical end of the site as a missile launch facility. Air Force Global Strike Command public reporting in 2011 stated that F.E. Warren would eliminate 50 former Peacekeeper missile silos and five associated alert facilities under the New Strategic Arms Reduction Treaty. The 2013 environmental assessment analyzed two launch-facility elimination methods: explosive implosion and backfill. Under the explosive implosion alternative, the silo door would be removed, dismantled, or destroyed, and the headworks and silo would be destroyed by explosives to a depth of up to 20 feet, then filled with debris and earth or gravel. Under the backfill alternative, the silo door would be removed, dismantled, or destroyed and the silo would be filled after the treaty observation period, with the launch facility support building also filled with earth or gravel.

New START verification requirements affected the sequence. The 2013 assessment states that launch facilities were subject to inspection within the first 30 days after notification, had to remain visible to national technical means of verification during dismantlement, and had to remain open for a 60-day period after dismantlement of the headworks so Russia could confirm that the LF had been dismantled. After that observation period, the rest of the silo would be filled and the site graded to blend with existing contours. The assessment also states that existing security fencing would remain in place.

For the full Sierra Flight narrative, see S-01 Missile Alert Facility / Launch Control Center

Site Cronology

• 1963-07-01 - The 90th Strategic Missile Wing was activated at F.E. Warren AFB.
• 1964-07-01 - The 400th Strategic Missile Squadron was organized during F.E. Warren's Minuteman expansion.
• 1965-06 - F.E. Warren's Minuteman field reached full operational status at the wing level; S-06 is treated as part of that mid-1960s operational Minuteman field.
• 1973 - F.E. Warren began converting its Minuteman force from Minuteman I to Minuteman III; the 400th Strategic Missile Squadron became the first all-Minuteman III squadron in the wing.
• 1974-09-03 - The 90th Strategic Missile Wing removed its last Minuteman IB from alert status.
• 1982-11-22 - President Ronald Reagan announced plans to deploy the MX / Peacekeeper missile at F.E. Warren.
• 1984-07 - Construction began for Peacekeeper support facilities at F.E. Warren.
• 1986-01-23 - The 400th Strategic Missile Squadron began phasing out Minuteman III missiles in preparation for Peacekeeper deployment.
• 1986-10-10 - The 90th Strategic Missile Wing recorded its first strategically postured Peacekeeper site.
• 1986-12-16 - The 90th Strategic Missile Wing reached initial operating capability for the Peacekeeper system.
• 1988 - F.E. Warren's public wing history states that 50 Peacekeeper missiles were brought on alert in modified Minuteman III silos.
• 2005-09-19 - The Peacekeeper alert mission ended at F.E. Warren; Air Force public releases stated that no Peacekeeper ICBMs remained on strategic alert in the 400th Missile Squadron.
• 2007-06 - The 2013 silo-elimination environmental assessment bibliography lists a Toltest, Inc. Tank Closure Report for Launch Facility Sierra-6, F.E. Warren AFB, Wyoming.
• 2011-02-05 - New START entered into force, setting treaty deadlines that shaped elimination of deactivated silos and associated alert facilities.
• 2013-03 - The Final Environmental Assessment for Minuteman III and Peacekeeper Silo Elimination evaluated dismantlement of 50 Peacekeeper launch facilities and five MAFs assigned to F.E. Warren AFB.
• 2013-06-29 - A secondary public photo source posted S-06 field photographs labeled general view, gate, fence and wind vane, unidentified feature, and roadside sign.
• 2018-02-04 - New START's elimination deadline applied to selected deactivated silos and associated alert facilities.

Read about the Peacekeeper Missile at F.E. Warren AFB

All Peacekeeper Missile Silo Locations

All Minuteman/Peacekeeper Missile Silo Locations