Watch the Falcon Heavy fire up its engines

The media briefing came after the agency formally pushed back the launch of the SpaceX Crew-9 mission to the International Space Station from mid-August to late-September.

Closing out an automated 18-hour rendezvous, a SpaceX Dragon cargo ship loaded with 7,000 pounds of supplies and equipment, including two add-on roll-out solar blankets, caught up with the International Space Station early Tuesday and moved in for a problem-free docking.

The four RS-25 engines at the bottom of NASA’s first Space Launch System core stage shut down about a minute into a ground test-firing Saturday that was supposed to last more than eight minutes.