A seemingly harmless everyday accident was responsible for the destruction of an Arkansas nuclear missile silo. Here's how ...

The giant, hardened concrete sliding dome that covers the missile silo at Titan II ICBM complex 570-9 south of Three Points, southwest of Tucson on Dec. 28, 1977.

Not to be confused with rockets, missiles provide guided, long-range explosive capability to various branches of the military ...

A silo near Sahuarita was decommissioned in 1982 and remains open as the Titan Missile Museum. It is operated by the Arizona Aerospace Foundation, which also operates the Pima Air and Space Museum.