Live coverage: SpaceX Falcon 9 rocket lifts off on first SDA mission

SpaceX’s first Falcon Heavy launch for the U.S. Air Force took a major step closer to liftoff with a hold-down engine firing Wednesday night at launch pad 39A at NASA’s Kennedy Space Center in Florida. Liftoff with a cluster of experimental satellites and weather monitoring craft is set for June 24.

The U.S. Air Force’s reusable Boeing-built X-37B spaceplane returned to Earth early Sunday with a touchdown at NASA’s Shuttle Landing Facility runway at the Kennedy Space Center in Florida, a few miles away from where it launched 780 days ago atop a SpaceX Falcon 9 rocket.

When SpaceX’s Falcon Heavy rocket finally takes off for the first time, a debut now scheduled this fall, there’s a good chance the commercial heavy-lifter will falter short of reaching orbit, company founder and chief designer Elon Musk said last week.