Faulty valve scuttles Starliner’s first crew launch

Enlarge / The Atlas V rocket and Starliner spacecraft on their launch pad Monday. (credit: NASA/Joel Kowsky)

Astronauts Butch Wilmore and Suni Williams climbed into their seats inside Boeing's Starliner spacecraft Monday night in Florida, but trouble with the capsule's Atlas V rocket kept the commercial ship's long-delayed crew test flight on the ground.

Around two hours before launch time, shortly after 8:30 pm EDT (00:30 UTC), United Launch Alliance's launch team stopped the countdown. "The engineering team has evaluated, the vehicle is not in a configuration where we can proceed with flight today," said Doug Lebo, ULA's launch conductor.

The culprit was a misbehaving valve on the rocket's Centaur upper stage, which has two RL10 engines fed by super-cold liquid hydrogen and liquid oxygen propellants.