Titan IV rocket. Liftoff of a Titan IV rocket, one of Americas largest launch vehicles. Titan IV is mainly used for launching heavy military satellites and deep space missions; it will also be used to launch parts of the International Space Station. Titan IV has two solidfuel boosters strapped on to the side of a liquidfuel two stage rocket. At launch it develops about 16 million newtons of thrust, most of this coming from the strapon boosters. Titan IV was developed because of the Space Shuttles inability to lift heavy payloads. Its first launch was in June 1989.