A missile launch facility, also known as an underground missile silo, launch facility (LF), or nuclear silo, is a vertical cylindrical structure constructed underground, for the storage and launching of intercontinental ballistic missiles (ICBMs), intermediate-range ballistic missiles (IRBMs), or medium-range ballistic missiles (MRBMs). Similar facilities can be used for anti-ballistic missiles (ABMs). The structures typically have the missile some distance below ground, protected by a large "blast door" on top. They are usually connected, physically and/or electronically, to a missile launch control center. With the introduction of the Soviet UR-100 and the U.S. Titan II missile series, underground silos changed in the 1960s. Both missile series introduced the use of hypergolic propellant, which could be stored in the missiles, allowing for rapid launches. Both countries' liquid-fueled missile systems were moved into underground silos. The introduction of solid fuel systems, in the later 1960s, made the silo moving and launching even easier. The underground missile silo has remained the primary missile basing system and launch facility for land-based missiles since the 1960s. Other than underground facilities, ballistic missiles can be launched from above-ground facilities, or can be launched from mobile platforms, e.g. transporter erector launchers, railcars, ballistic missile submarines or airplanes.
Nazi Germany The La Coupole facility is the earliest known precursor to modern underground missile silos still in existence. It was built by the forces of Nazi Germany in northern Occupied France, between 1943 and 1944, to serve as a launch base for V-2 rockets. The facility was designed with an immense concrete dome to store a large stockpile of V-2s, warheads and fuel, and was intended to launch V-2s on an industrial scale. Dozens of missiles a day were to be fuelled, prepared and rolled just outdoors of the facility's concrete casing, launched from either of two outdoor launch pads in rapid sequence against London and southern England. A similar-purpose but less-developed facility, the Blockhaus d'Eperlecques, had also been built, some 14.4 kilometers (8.9 miles) north-northwest of La Coupole, and closer to intended targets in southeastern England. Following repeated heavy bombing by Allied forces during Operation Crossbow, the Germans were unable to complete construction of the works and the complex never entered service. The United Kingdom conducted post-war investigations, determining that it was "an assembly site for long projectiles most conveniently handled and prepared in a vertical position".
United States The British idea of an underground missile silo was adopted and developed by the United States for missile launch facilities for its intercontinental ballistic missiles. Most silos were based in Colorado, Nebraska, North Dakota, South Dakota, Missouri, Montana, Wyoming and other western states. There were three main reasons behind this siting: reducing the flight trajectory between the United States and the Soviet Union, since the missiles would travel north over Canada and the North Pole; increasing the flight trajectory from SLBMs on either seaboard, giving the silos more warning time in the event of a nuclear war; and locating obvious targets as far away as possible from major population centres. They had many defense systems to keep out intruders and other defense systems to prevent destruction (see Safeguard Program). In addition to the three previously mentioned siting reasons, the US Air Force had other site requirements that were also taken into account such as, having the sites be close enough to a populace of roughly 50,000 people for community support along with making sure launch locations were far enough apart that a 10 MT detonation on or near strategic locations would not knock out other launch facilities in the area. "In 1960 the US Army established the Corps of Engineers Ballistic Missile Construction Office (CEBMCO), an independent organization under the Chief of Engineers, to supervise construction". This newly established organization was able to produce Minutemen Launch silos at an extremely fast rate of ~1.8 per day from 1961 to 1966 where they built a total of 1,000 Minuteman missile silos. The United States built many missile silos in the Midwest, away from populated areas. Many were built in Colorado, Nebraska, South Dakota, and North Dakota. The U.S. spent considerable effort and funds in the 1970s and 1980s designing a replacement, but none of the new and complex system designs were ever produced. The United States has many silo-based warheads in service, however, they have lowered their number to around 1800 and have transferred most of their missiles to nuclear submarines and are focusing on more advanced conventional weapons. Today they are still used, although many have been decommissioned and hazardous materials removed. The increase of decommissioned missile silos has led governments to sell some of them to private individuals. Some buyers convert them into unique homes, advanced safe rooms, or use them for other purposes. They are popular sites of urban exploration.
Atlas facilities The Atlas missiles used four different storage and launching methods.
The first version were vertical and above-ground launchers, at Vandenberg Air Force Base on the Central Coast of California. The second version were stored horizontally in a shed-like structure with a retractable roof, to then be raised to the vertical and launched, at Francis E. Warren Air Force Base in Wyoming. The third version were stored horizontally, but better protected in a concrete building known as a "coffin", then raised to the vertical shortly before launch. These rather poorly protected designs were a consequence of the cryogenic liquid fuels used, which required the missiles to be stored unfueled and then be fueled immediately prior to launch. The fourth version were stored vertically in underground silos, for the Atlas F ICBM. They were fueled in the silo, and then since they could not be launched from within the silo, were raised to the surface to launch. In 2000 William Leonard Pickard and a partner were convicted, in the largest lysergic acid diethylamide (LSD) manufacturing case in history, of conspiracy to manufacture large quantities of LSD in a decommissioned SM-65 Atlas missile silo (548-7) near Wamego, Kansas.
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