Boeing has called off its first astronaut launch because of a fluttering rocket valve. The two NASA test pilots had just strapped into Boeing’s Starliner capsule when the countdown was halted Monday night, two hours before the planned liftoff from Cape Canaveral, Florida. United Launch Alliance’s CEO says the problem involves an oxygen pressure-relief valve on the Atlas rocket’s upper stage. Liftoff is now off until at least Friday. If the valve needs to be replaced, the flight to the International Space Station would bump into next week.
