Titan II

The Titan II succeeded the Titan I — the first American two-stage ICBM and the first that could be launched from its silo — with double the payload and a decisive change of propellant: instead of its predecessor's cryogenic combination it used storable hydrazine-based hypergolic propellants, which ignited reliably on contact and needed no fuelling before launch. That cut reaction time and allowed the missile to be fired from inside the silo. Each stage was three metres in diameter, with fuel and oxidiser tanks in tandem whose walls formed the skin of the missile, and the complete vehicle reached 154,000 kilograms. It attained initial operating capability in October 1963 carrying a single W-53 warhead in a Mark 6 re-entry vehicle.

The first Titan II, missile N-2, lifted off from pad LC-16 at Cape Canaveral in March 1962 and performed extremely well: it flew some 8,000 kilometres downrange and placed its re-entry vehicle in the intended area. The following tests exposed the problem the programme would carry for years, the longitudinal oscillation known as pogo, worrying above all because the missile was meant to carry crews. As a weapon it spent a quarter of a century in Strategic Air Command silos, with serious propellant-leak accidents along the way; after the 1978 and 1980 events, deactivation of the system began in July 1982 and the last missile, in silo 373-8 near Judsonia, Arkansas, was deactivated on 5 May 1987.

Its space career ran in parallel and lasted longer. The Titan II GLV version launched all twelve Gemini capsules, ten of them crewed, in the mid-1960s. Decommissioned missiles were then rebuilt as launch vehicles: designated Titan 23G, they needed few changes beyond the payload interface, and the first flew successfully on 5 September 1988 from Vandenberg. Among its payloads was NASA's Clementine lunar spacecraft, launched in January 1994. The last Titan II lifted off on 18 October 2003 with a DMSP weather satellite, closing four decades of service with a capacity of 3,600 kilograms to low Earth orbit.