Delta IV Heavy rocket to launch classified mission on penultimate flight.
The United Launch Alliance's Delta IV Heavy rocket is set to launch on Wednesday, June 21, on a mission for the US National Reconnaissance Office called NROL-68. The satellite's details are classified, but the mission patch offers some clues. The Delta IV Heavy rocket will generate 2.1 million pounds of thrust at liftoff and this will be its second-to-last mission. The rocket is being phased out in favor of the new Vulcan Centaur, which is set to debut later this year.
