After nearly 17 years of service, the Delta IV Medium has been launched on its final mission. The Delta IV Medium+ (4,2) was launched from Cape Canaveral carrying the second GPS III satellite for the US Air Force.
The Delta IV rocket utilised for today’s launch featured a single common core, two solid-fuel boosters, and a four-meter fairing. The configuration, which is referred to as the Delta IV Medium+ (4,2) has now been launched 14 times, including the Delta IV’s maiden flight on November 20, 2002.
Today’s mission blasted off from Cape Canaveral’s Space Launch Complex 37B at 13:06 UTC. Following a beautiful launch, the Delta IV Medium’s solid rocket boosters were jettisoned approximately two minutes into the flight. An additional two minutes later, the RS-68A engine powering the rocket’s core stage shut down followed soon after by first stage separation.
Once the first stage had been successfully separated, the rocket’s second stage completed the first of three planned burns. Approximately one hour into the mission, a second burn was completed followed by a half an hour coast phase. Just over two hours after liftoff, the GPS III navigation satellite drifted gently away from the rocket’s upper stage into its designated orbit.
With its mission now complete, the rocket’s DCSS engine will complete the third and final planned burn to place the stage into a reentry orbit. The burn is used to ensure the stage does not add to the ever-growing cloud of space junk orbiting Earth. It will make a destructive impact with the ocean at just over 7 hours into the mission.
The decision to retire the Delta IV Medium was made largely due to United Launch Alliance, operators of the Delta IV and Atlas V rockets, concluding that any capabilities the Delta IV Medium could offer, the Atlas V could offer equally as well at a more competitive price. Additionally, the capabilities offered by the Atlas V family will also soon be eclipsed by the operator’s next-generation Vulcan Centaur rocket, adding yet another nail in the coffin of the Delta IV.