Watch the Falcon 9 launch from pad 39A

Keeping with its mantra of fly, fix and fly again, SpaceX says it has resolved a valve problem that kept one of its Falcon 9 boosters from successfully touching down on a barge in the Atlantic Ocean in April, ahead of another landing attempt after a launch from Cape Canaveral set for Sunday.

SpaceX will sacrifice a Falcon 9 rocket Sunday in a fiery test a minute-and-a-half after liftoff from Florida’s Space Coast to prove the company’s Crew Dragon spacecraft can safely push astronauts away from a failing launch vehicle, simulating a daring maneuver that would only be attempted on a piloted mission during an in-flight emergency.

One of the two Falcon 9 rockets SpaceX planned to take off in a span of less than five hours earlier this week will remain grounded indefinitely, preventing Cape Canaveral from hosting two launches on the same day for the first time in decades. But the military-run Eastern Range was ready for the back-to-back missions, and probably won’t have to wait long for the next chance for a launch doubleheader.