Posted: Sat, May 11, 2024, 10:58 AM ET (1458 GMT)
A problem with a valve in the Atlas 5 upper stage scrubbed the first crewed launch of Boeing's CST-100 Starliner Monday night. Controllers halted the countdown about two hours before the scheduled 10:34 pm EDT (0234 GMT Tuesday) liftoff because of a "buzzing" noise from a liquid oxygen relief valve in the Centaur upper stage. That noise was caused by repeated cycling of the valve that engineers concluded could cause the valve to exceed its rated life. NASA has rescheduled the launch for no earlier than May 17 in order to roll the rocket back to its hangar for repairs. Starliner itself was in good shape, with preparations for launch running ahead of schedule at the time of the scrub.

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