Titan (rocket family)

Titan was a family of United States expendable rockets used between 1959 and 2005. Titan I and Titan II were part of the US Air Force's intercontinental ballistic missile fleet until 1987. The space launch vehicle versions contributed the majority of the 368 Titan launches, including all the Project Gemini crewed flights of the mid-1960s. Titan vehicles were also used to lift US military payloads as well as civilian agency intelligence-gathering satellites and to send highly successful interplanetary scientific probes throughout the Solar System. Titan was a family of United States expendable rockets used between 1959 and 2005. Titan I and Titan II were part of the US Air Force's intercontinental ballistic missile fleet until 1987. The space launch vehicle versions contributed the majority of the 368 Titan launches, including all the Project Gemini crewed flights of the mid-1960s. Titan vehicles were also used to lift US military payloads as well as civilian agency intelligence-gathering satellites and to send highly successful interplanetary scientific probes throughout the Solar System. The HGM-25A Titan I was the first version of the Titan family of rockets. It began as a backup ICBM project in case the SM-65 Atlas was delayed. It was a two-stage rocket operational from early 1962 to mid-1965 whose LR-87 booster engine was powered by RP-1 and liquid oxygen. The ground guidance for the Titan was the UNIVAC ATHENA computer, designed by Seymour Cray, based in a hardened underground bunker. Using radar data, it made course corrections during the burn phase. Unlike decommissioned Thor, Atlas, and Titan II missiles, the Titan I inventory was scrapped and never reused for space launches or RV tests, as all support infrastructure for the missile had been converted to the Titan II/III family by 1965. Most of the Titan rockets were the Titan II ICBM and their civilian derivatives for NASA. The Titan II used the LR-87-5 engine, a modified version of the LR-87, that used a hypergolic propellant combination of nitrogen tetroxide for its oxidizer and Aerozine 50 (a 50/50 mix of hydrazine and UDMH) instead of the liquid oxygen and RP-1 propellant of the Titan I. The first Titan II guidance system was built by AC Spark Plug. It used an Inertial measurement unit made by AC Spark Plug derived from original designs from the Charles Stark Draper Laboratory at MIT. The missile guidance computer (MGC) was the IBM ASC-15. When spares for this system became hard to obtain, it was replaced by a more modern guidance system, the Delco Electronics Universal Space Guidance System (USGS). The USGS used a Carousel IV IMU and a Magic 352 computer. The USGS was already in use on the Titan III space launcher when work began in March 1978 to replace the Titan II guidance system. The main reason was to reduce the cost of maintenance by $72 million per year; the conversions were completed in 1981. Liquid oxygen is dangerous to use in an enclosed space, such as a missile silo, and cannot be stored for long periods in the booster oxidizer tank. Several Atlas and Titan I rockets exploded and destroyed their silos. The Martin Company was able to improve the design with the Titan II. The RP-1/LOX combination was replaced by a room-temperature fuel whose oxidizer did not require cryogenic storage. The same first-stage rocket engine was used with some modifications. The diameter of the second stage was increased to match the first stage. The Titan II's hypergolic fuel and oxidizer ignited on contact, but they were highly toxic and corrosive liquids. The fuel was Aerozine 50, a 50/50 mix of hydrazine and UDMH, and the oxidizer was nitrogen tetroxide. There were several accidents in Titan II silos resulting in loss of life and/or serious injuries. In August 1965, 53 construction workers were killed in Arkansas when hydraulic fluid used in the Titan II caught fire from a welder's torch in a missile silo northwest of Searcy. The liquid fuel missiles were prone to developing leaks of their toxic propellants. At a silo outside Rock, Kansas, an oxidizer transfer line carrying nitrogen tetroxide (NTO) ruptured on August 24, 1978. An ensuing orange vapor cloud forced 200 rural residents to evacuate the area. A staff sergeant of the maintenance crew was killed while attempting a rescue and a total of twenty were hospitalized. Another site at Potwin, leaked NTO oxidizer in April 1980 with no fatalities, and was later closed. In September 1980, at Titan II silo 374-7 near Damascus, Arkansas, a technician dropped an 8 lb (3.6 kg) socket that fell 70 ft (21 m), bounced off a thrust mount, and broke the skin of the missile's first stage, over eight hours prior to an eventual explosion. The puncture occurred about 6:30 p.m. and when a leak was detected shortly after, the silo was flooded with water and civilian authorities were advised to evacuate the area. As the problem was being attended to at around 3 a.m., leaking rocket fuel ignited and blew the 8,000 lb (3,630 kg) nuclear warhead out of the silo. It landed harmlessly several hundred feet away. There was one fatality and 21 were injured, all from the emergency response team from Little Rock AFB. The explosion blew the 740-ton launch tube cover 200 ft (60 m) into the air and left a crater 250 feet (76 m) in diameter. The 54 Titan IIs, in Arizona, Arkansas, and Kansas, were replaced in the U.S. arsenal by 50 MX 'Peacekeeper' solid-fuel rocket missiles in the mid-1980s, the last Titan II silo was deactivated in May 1987. The 54 Titan IIs had been fielded along with a thousand Minuteman missiles from the mid-1960s through the mid-1980s.