Titan (rocket Family) - Titan IV

The Titan IV is a "stretched" Titan III with non-optional solid rocket boosters on its sides. The Titan IV could be launched with a Centaur upper stage, the USAF Inertial Upper Stage (IUS), or no upper stage at all. This rocket was used almost exclusively to launch American military or civilian intelligence agency payloads. However it was also used for a purely scientific purpose to launch the NASA - ESA Cassini / Huygens space probe to Saturn in 1997. The primary intelligence agency that needed the Titan IV's launch capabilities was the National Reconnaissance Office, the NRO.

By the time it became available, the Titan IV was the most powerful unmanned rocket produced and used by United States, because the extremely large and powerful Saturn V rocket had not been available for some years. Still, the Titan IV was considered to be quite expensive to manufacture and use. By the time the Titan IV became operational, the requirements of the U.S. Department of Defense and the NRO for launching satellites had tapered off due to improvements in the longevity of reconnaissance satellites, and in addition, the declining foreign threat to the security of the United States that followed the internal disintegration of the Soviet Union.

As a result of these events, and improvements in technology, when including the cost of the ground operations and facilities for the Titan IV at Vandenberg Air Force Base for launching satellites into polar orbits, the unit cost of a Titan IV launch was very high. Titan IVs were also launched from the Cape Canaveral Air Force Station in Florida for non-polar orbits.