U.S. spy satellite launched into orbit aboard Delta 4 Heavy rocket from California for final time

A classified satellite for the U.S. National Reconnaissance Office launched into orbit aboard a United Launch Alliance Delta 4 Heavy rocket on Saturday. The NROL-91 spy satellite lifted off at 3:25 p.m. from Vandenberg Space Force Base in California's Santa Barbara County.

It was the last launch of a Delta 4 from the West Coast. Additional launches are planned from Florida before the Deltas are replaced by ULA's next-generation Vulcan Centaur rockets.

"The Delta IV Heavy has proven to be an integral part of the NRO's history, helping us build the architecture for the world's best space-based intelligence, surveillance and reconnaissance," said NRO Director Dr. Chris Scolese in a statement.