ULA To Launch NROL-91 From The West Coast

Written By: Josh G for Onkla

The Delta IV Heavy rocket will launch later today at 5:53pm EDT from Space Launch Complex 6 at the Vandenberg Space Force Base. This will be the third to final Delta IV Heavy launch ever, and the last Delta IV Heavy to launch from Vandenberg Space Force Base.

Credit: SpaceFlight Now -- Delta IV Heavy launch from Vandenberg SFB carrying NROL-82

The Delta IV Heavy will liftoff from Space Launch Complex 6 at 5:53pm Eastern Daylight Time, carrying National Reconnaissance Office Launch 91 (NROL-91) into orbit. Not much is known about the payload as the Nation Reconnaissance Office (NRO) is very secretive about their spacecraft.

This will be the third to final Delta IV Heavy launch and the final Delta IV Heavy launch from the west coast. This is because United Launch Alliance, which is in charge for launching Delta IV Heavy, is developing a new rocket called Vulcan Centaur. So they have decided to stop launching their other rockets, the Atlas and Delta rocket series. Unlike Atlas however, Delta is only scheduled to fly two more flights after this mission, with the final launch being in January of 2024.

Delta IV Heavy is most famous for the rocket lighting itself on fire at engine ignition. This is due to the RS-68A main engines on all three cores of the vehicle. During the engine ignition sequence the hydrogen valve needs to be opened two seconds prior to the oxygen valve on each engine. Without the controlled mixture, the hydrogen reacts with the oxygen in the air, and ignites and creates the famous fireball. To minimize the size of the flame, ULA staggers the engine ignitions. With first Booster 1, and then it is followed by Booster 2 and the center core.

The flames are NORMAL, this is the base of Delta IV H

Join us LIVE for this mission on the Onkla YouTube channel!

Onkla NROL-91 Livestream: https://www.youtube.com/watch?v=CZuKbM85FzQ