Waterside view of Delta 4 GPS 2F-6 Launch

A replay of the United Launch Alliance Delta 4 rocket launching on the NROL-45 satellite-deployment mission for the National Reconnaissance Office from Vandenberg Air Force Base, California.

Rolling toward a mid-May deployment of a clandestine spy satellite, United Launch Alliance’s triple-body Delta 4-Heavy rocket moved from its Cape Canaveral assembly building to pad 37B yesterday.

The 100th rocket in America’s Evolved Expendable Launch Vehicle program, the current fleet of boosters used by the nation to get its critical assets into space, was rolled to the pad Friday morning for a vital mission on Saturday.