Boeing’s first astronaut launch, slated to carry Butch Wilmore and Suni Williams to the International Space Station, has been postponed due to a valve problem on the Atlas V rocket. The issue, involving an oxygen pressure-relief valve on the rocket’s upper stage, halted the countdown just two hours before the planned liftoff. NASA and United Launch Alliance engineers are evaluating the valve’s condition and will decide whether to replace it or proceed with the launch as early as Tuesday night. This delay underscores the challenges faced by Boeing as it works to certify Starliner as a commercial crew vehicle capable of transporting astronauts to the ISS.