United Launch Alliance’s penultimate Delta IV Heavy rocket took flight on the NROL-68 mission Thursday, lofting a secretive payload for the National Reconnaissance Office. Liftoff, from Space Launch Complex 37B at Cape Canaveral, is expected at 05:18 AM EDT (10:18 UTC). The mission was set to launch on Wednesday before ULA scrubbed the attempt due to an issue with a ground system pneumatic valve.
