Video: Delta 4 launches before dawn from California

Running through a practice countdown to check systems before launching a NASA sample-return probe to Asteroid Bennu in exactly two weeks, an Atlas 5 successfully completed its Wet Dress Rehearsal today.

Hardware for two air-dropped Pegasus XL launchers previously purchased by Stratolaunch, a space launch company founded by the late billionaire Paul Allen, are now back under Northrop Grumman control and for sale to NASA, the Air Force, or commercial satellite operators, industry officials said.

A huge U.S.-built, Canadian-owned communications satellite weighing 15,600 pounds, the heaviest spacecraft of its kind ever launched, is mounted to a Falcon 9 rocket for liftoff early Sunday from Cape Canaveral on a heavy-lifting mission that previously would have required SpaceX to throw away the launcher’s first stage booster.