SpaceX delays flight to replace NASA’s stuck astronauts after launch pad problem

CAPE CANAVERAL, Fla. (AP) — A launch pad problem prompted SpaceX to delay a flight to the International Space Station on Wednesday to replace NASA’s two stuck astronauts.

The new crew needs to get to the International Space Station before Butch Wilmore and Suni Williams can head home after nine months in orbit.

Concerns over a critical hydraulic system arose less than four hours before the Falcon rocket’s planned evening liftoff from NASA’s Kennedy Space Center. As the countdown clocks ticked down, engineers evaluated the hydraulics used to release one of the two arms clamping the rocket to its support structure. This structure needs to tilt back right before liftoff.

Already strapped into their capsule, the four astronauts awaited a final decision, which came down with less than an hour remaining in the countdown. SpaceX canceled for the day. Officials later said the launch was off until at least Friday.

Once at the space station,…