Waterside view of Delta 4 GPS 2F-6 Launch

Payload readiness has delayed next weekend’s planned Delta 4-Heavy rocket launch for the U.S. National Reconnaissance Office.

The first of up to seven United Launch Alliance missions lifted off Jan. 19 from Vandenberg Air Force Base in California, where a Delta 4-Heavy launcher fired into orbit with 2.1 million pounds of thrust from three hydrogen-fueled RS-68A main engines with a U.S. government spy satellite.

The USSF-87 will be the second national security flight for United Launch Alliance’s Vulcan rocket and the fourth flight of this type of rocket to date. Liftoff from pad 41 at Cape Canaveral Space Force Station is scheduled for 3:30 a.m. EST (0830 UTC).