Video: OA-7 Cygnus freighter arrives at its orbital destination

Ready for blastoff just after sunset Wednesday with a classified payload for the U.S. government’s spy satellite agency, a United Launch Alliance Atlas 5 rocket rolled out to its launch pad at Cape Canaveral late Tuesday afternoon after an unplanned trip back inside its integration building for repairs.

United Launch Alliance will launch the USSF-106 mission as its first flight for the U.S. Space Force using a Vulcan rocket. The vehicle will carry two satellite missions onboard.

A solid-fueled rocket motor mounted horizontally on a Utah hillside ignited and powered up to more than 3 million pounds of thrust Tuesday in a final full-up test-firing before a similar booster helps propel NASA’s huge Space Launch System away from Earth on a demonstration flight in 2018.