The United Launch Alliance Delta 4 heavy launch vehicle was launched aboard a U.S. spy satellite at Vandenberg Air Force Base in California.
On September 24, the Delta 4 Heavy successfully launched a mission code-named NROL-91 to send a high-resolution imaging satellite of the National Reconnaissance Office ( NRO ) into low-Earth orbit.
Delta IV Heavy
The Delta IV Heavy ( Delta 9250H ) combines a 5 m ( 16 ft ) diameter DCSS and payload fairing with two additional CBCs.
These are strap-on boosters which are separated earlier in the flight than the center CBC.
As of 2007, a longer 5 meter diameter composite fairing was standard on the Delta IV Heavy, with an aluminum isogrid fairing also available.
The aluminum trisector (three-part) fairing was built by Boeing and derived from a Titan IV fairing.
The trisector fairing was first used on the DSP-23 flight.The Delta IV with the extended fairing is over 62 m (203 ft) tall.
The heavy rocket is expected to be officially retired in 2024 and replaced by a new generation of Vulcan carrier rockets to carry out US military satellite deployment missions.