KENNEDY SPACE CENTER, Fla. — The Space Coast witnessed a rare launch of the SpaceX Falcon Heavy rocket Friday on a mission for NASA that also featured the double sonic booms of its returning first-stage boosters. Flying for only the eighth time ever, and its ever launch for NASA, the Falcon Heavy, which is essentially three Falcon 9 boosters strapped together, avoided weather concerns for a 10:19 a.m. liftoff from Kennedy Space Center’s Launch Pad 39-A. The rocket blasted through the haze of heavy cloud cover popping in and out of view through slivers of blue sky on its way into space. Teams b...