After a fiery finale, the Delta rocket family now belongs to history

Enlarge / In this video frame from ULA’s live broadcast, three RS-68A engines power the Delta IV Heavy rocket into the sky over Cape Canaveral, Florida. (credit: United Launch Alliance)

The final flight of United Launch Alliance’s Delta IV Heavy rocket took off Tuesday from Cape Canaveral, Florida, with a classified spy satellite for the National Reconnaissance Office.

The Delta IV Heavy, one of the world’s most powerful rockets, launched for the 16th and final time Tuesday. It was the 45th and last flight of a Delta IV launcher and the final rocket named Delta to ever launch, ending a string of 389 missions dating back to 1960.

United Launch Alliance (ULA) tried to launch this rocket on March 28 but aborted the countdown about four minutes prior to liftoff due to trouble with nitrogen pumps at an off-site facility at Cape Canaveral. The nitrogen is necessary for purging parts inside the Delta IV rocket before launch, reducing the risk of a fire or explosion during the countdown.