The agency said Saturday that NASA had delayed the SpaceX Crew-1 mission from early November to mid-November. The mission will bring three NASA astronauts and one astronaut from the Jaxa space agency in Japan to the International Space Station.

The first phase of the Falcon 9 rocket is scheduled for October 31, a six-month mission planned to allow time to resolve issues with the engine’s gas generators. NASA said in a statement. During the launch, American astronauts Michael Hopkins, Victor Glover, Shannon Walker, and Japanese astronaut Sochi Noguchi will be on SpaceX’s first Operation Crude mission to ISS.

Crew-1 is one of six missions that SpaceX plans to send to the ISS under a 2014 agreement with NASA as part of a commercial crew program that brought private space companies into the U.S. space program.

SpaceX’s first crew dragon flight, DM-2 or Demo-2, was a test mission, bringing NASA astronauts Doug Hurley and Bob Behenken to the RSS in May for a two-month visit. The crew docked with the Dragon RSS and returned safely to Earth on August 2, providing NASA with the data needed to certify future trips in and out of the spacecraft with future astronauts on board.