Elon Musk's SpaceX launches Falcon 9 after six-month delay -- and sticks the landing

CAPE CANAVERAL, Fla. — SpaceX's Falcon 9 is back: back in service, blasting off Monday night after a six-month stand-down; and — just as remarkably for the company's long-term plans — the rocket is back on the ground, in one piece. The space company made its triumphant return to flight with a flawless 8:29 p.m. EST…