ULA successfully launched a Delta IV Heavy (DELTA IVH-4050H (Upgraded) from Vandenberg, California, USA at 2225 GMT on 24 September 2022. The vehicle was carrying NRO L-91 (Orion 12), a classified payload for the National Reconnaissance Office (NRO). Details of the payload are scant but it is thought to be a very high resolution electro-optical satellite of the Lockheed Martin KH-11/Advanced Crystal series using a very large aperture optical telescope. A 5-meter diameter payload fairing was used.
The Delta IV Heavy is an unusual rocket in using liquid Hydrogen and LOx (Liquid Oxygen) propellants for all the stages – including the two major booster rockets. The core and two booster stages use the RS-68A engine, whereas the DCSS-5 upper stage uses the RL-10C-2-1. The orbit used for the NRO-L91 mission is a near polar sun-synchronous low Earth orbit.
Launch of NRO-L91 by Delta IV Heavy. Courtesy: ULA
