The Titan II space launch vehicle is a two-stage liquid fueled booster, designed to provide a small-to-medium weight class capability. It is able to lift approximately 4,200 pounds (1,900 kg) into a polar low-Earth circular orbit. The first stage consists of two ground ignited Aerojet LR87 liquid propellant rocket engines, while the second stage consists of an Aerojet LR91 liquid propellant rocket engine.
The Titan rocket family was established in October 1955, when the Air Force awarded the Glenn L. Martin Company a contract to build an intercontinental ballistic missile (ICBM). It became known as the Titan I, the nation’s first two-stage ICBM and first underground silo-based ICBM. The Martin Company recognized that the Titan I could be further improved and presented a proposal to the U.S. Air Force for an improved version. It would carry a larger warhead over a greater range with more accuracy and could be fired more quickly. The Martin company received a contract for the new missile, designated SM-68B Titan II, in June 1960. The Titan II was 50% heavier than the Titan I, with a longer first stage and a larger diameter second stage. The Titan II also used storable propellants, Aerozine 50 and dinitrogen tetroxide. The Titan I, whose liquid oxygen oxidizer must be loaded immediately before launching, had to be raised from its silo and fueled before launch. The use of storable propellants enabled the Titan II to be launched within 60 seconds directly from within its silo. Their hypergolic nature made them dangerous to handle; a fuel leak could (and did) lead to explosions.
The first flight of the Titan II was in December 1961 and the missile, now designated LGM-25C, reached initial operating capability in October 1963. The Titan II contained one W-53 nuclear warhead in a Mark 6 re-entry vehicle with a range of 9,325 miles (15,000 km). The W-53 had a yield of 9 megatons. This warhead was guided to its target using an inertial guidance unit. The 54 deployed Titan IIs formed the backbone of America’s strategic deterrent force until the LGM-30 Minuteman ICBM was deployed en masse during the early to mid 1960's . Ten Titan IIs were flown in NASA’s Gemini manned space program in the mid-1960s. It was also supposed to be used for a nuclear weapon that the United States claimed had a 35 megaton capability. This would have made this warhead one of the most powerful ever, and in terms of power to weight ratio, advantageous over the B-41 nuclear bomb by almost double.
Because of the volatility of the liquid fuel, and the problem with aging seals, the Titan II missiles had been scheduled to be retired beginning in 1971. After two accidents, deactivation of the Titan II ICBM system finally began in July 1982. The last Titan II missile, located at Silo 373-8 near Judsonia, Arkansas, was deactivated on May 5, 1987. The deactivated missiles are now in storage at Davis-Monthan AFB, Arizona.
A fire and resultant loss of oxygen when a high pressure hydraulic line was cut with a torch in a missile silo (373-4) near Searcy, Arkansas killed 53 people, mostly civilian repairmen. An oxidizer leak on August 24, 1978 killed two at McConnell AFB. A leak after a socket rolled off a platform and punctured the Stage I fuel tank subsequently caused the entire silo to explode, killed an Air Force Sergeant and destroyed the silo (374-7, near Damascus, Arkansas) at Little Rock AFB on September 19, 1980. A "B" grade movie portrays this event, "Disaster at Silo Seven".
Number of Titan II missiles in service, by year:
The Titan II space-launch vehicles were purpose-built as space launchers or are decommissioned ICBMs that have been refurbished and equipped with hardware required for use as space launch vehicles. All twelve Gemini capsules were launched by Titan II launchers. The Titan 23B was a Titan II with an Agena third stage that was used to launch reconnaissance satellites.
The Martin Marietta Astronautics Group was awarded a contract in January 1986 to refurbish, integrate, and launch fourteen Titan II ICBMs for government space launch requirements. These were designated Titan 23G. The Air Force successfully launched the first Titan 23G space launch vehicle from Vandenberg AFB September 5, 1988. NASA’s Clementine spacecraft was launched aboard a Titan 23G in January 1994.