Four astronauts will have to wait at least until Friday to head the International Space Station.

This otherwise routine rotation of crew on the space station is garnering extra attention because it will at last allow the return to Earth of Suni Williams and Butch Wilmore, two NASA astronauts whose brief scheduled visit to the space station last June was unexpectedly stretched to more than nine months.

The scrub of the flight attempt on Wednesday night, which occurred less than 45 minutes before the scheduled liftoff, means Mr. Wilmore and Ms. Williams’ stay in orbit will also be extended at least one more day. During the countdown, SpaceX encountered a hydraulic issue with a clamp arm that holds onto the Falcon 9 rocket before it launches.

NASA announced Wednesday night that the next launch attempt would be on Friday at 7:03 p.m. Eastern time. Mission managers decided not to attempt a launch on Thursday because of high winds and rain predicted along the launch path.

Launch teams are working to fix the problem with the clamp arm.

Here’s other information about the mission, which is named Crew-10 because it is the 10th such mission by SpaceX ferrying crew to and from the space station.

Anne McClain of NASA is the commander of Crew-10, and Nichole Ayers of NASA is the pilot. The other two crew members are Takuya Onishi of JAXA, the Japanese space agency, and Kirill Peskov of Roscosmos, the Russian space agency.

This will be the first spaceflight for Ms. Ayers and Mr. Peskov and the second spaceflight for Ms. McClain and Mr. Onishi.

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