SM-68 Titan

The SM-68 Titan was a United States Air Force Intercontinental Ballistic Missile (ICBM) that was in service from 1962 to 1987. It was a two-stage, liquid-fueled missile designed to deliver a thermonuclear warhead to targets within the Soviet Union. The Titan I, the initial version, used RP-1 (rocket propellant-1, a refined kerosene) and liquid oxygen as propellants, requiring cryogenic handling. This made it slow to launch as it needed to be fueled before launch.

The Titan II, an improved variant, used storable hypergolic propellants (aerozine 50 and nitrogen tetroxide), which meant it could be stored in a ready-to-launch state. This significantly reduced the launch time and improved the missile's overall effectiveness. The Titan II was housed in hardened silos for protection against a nuclear attack.

The Titan II was also used as a launch vehicle for the Gemini program, which aimed to develop the techniques necessary for lunar exploration. Modified Titan II missiles launched ten crewed Gemini missions in 1965 and 1966.

The Titan ICBM program was eventually phased out as newer, more advanced ICBMs like the Minuteman III and MX Peacekeeper were developed and deployed. However, the Titan II's legacy continued as a launch vehicle for various payloads, including military satellites and scientific missions. The last Titan II launch occurred in 2003.