"Delta 4 Heavy: The Fiery Final Flight"

United Launch Alliance launched its 16th and final triple-core Delta 4 Heavy rocket, carrying a classified spy satellite for the National Reconnaissance Office. The launch marked the end of a storied era in U.S. rocketry, with the Delta 4 family dating back to the dawn of the space age. The satellite's mission and details were kept classified, but it is believed to be an advanced signals intelligence satellite bound for a geosynchronous orbit. The retirement of the Delta 4 Heavy paves the way for United Launch Alliance's transition to the next-generation Vulcan rockets.