From 1963 until the early 1990s, the missile silo at Delta-09 contained a fully operational Minuteman Missile, bearing a 1.2 megaton nuclear warhead. The Delta-09 missile silo was one of 150 spread across western South Dakota. In total there were 1,000 Minuteman missiles deployed from the 1960's into the early 1990's. Visitors can now tour the site daily. The launch facility consists of a silo 12 feet in diameter and 80 feet deep made of reinforced concrete with a steel-plate liner. The door to the silo has been welded and fitted with a glass roof, and an unarmed missile placed inside. For safety reasons, tours are not conducted underground. In addition to the missile and silo, visitors will see support structures such as antennas and motion sensors.