The United Launch Alliance Atlas 5 rocket with the NROL-52 spacecraft aboard moved to the launch pad this morning for liftoff Saturday to serve the national interest. Liftoff is scheduled for 3:31 a.m. EDT (0731 GMT).

SpaceX launched a Falcon 9 rocket from Cape Canaveral Air Force Station at 6:24 p.m. EST (2324 GMT) Thursday with the U.S. military’s next GPS navigation satellite. The mission was delayed more than a month after a previous countdown was aborted seconds before liftoff.

SpaceX and its visionary founder Elon Musk win the lion’s share of public attention in the commercial rocket arena, with dramatic, increasingly routine booster landings and spectacular stunts like the launch of Musk’s Tesla Roadster on the maiden flight of the company’s new Falcon Heavy rocket last month.