Video: Weather causes Atlas 5 countdown hold

United Launch Alliance teams began stacking an Atlas 5 rocket inside a vertical hangar at Cape Canaveral Monday in preparation for an early February launch with the Solar Orbiter spacecraft, a joint U.S.-European probe that will take the first pictures of the sun’s poles.

United Launch Alliance engineers filled a Delta 4-Heavy rocket with super-cold liquid hydrogen and liquid oxygen propellants Friday at Cape Canaveral Air Force Station during a practice countdown before the heavy-lifter’s scheduled liftoff in June with a top secret U.S. government spy satellite.

United Launch Alliance’s 50th mission for the U.S. Air Force lifted off at 12:15 a.m. EDT (0415 GMT) Wednesday. An Atlas 5 rocket launched from Cape Canaveral with the Air Force’s fourth Advanced Extremely High Frequency communications satellite.