NASA's Kennedy Space Center in Florida was scheduled to launch Crew-6, a four-person ISS mission, early Sunday morning (Feb. 26).

After a lengthy flight readiness review (FRR) on Tuesday (Feb. 21), NASA and SpaceX delayed liftoff by 24 hours. SpaceX's Falcon 9 rocket will launch Crew-6's Dragon capsule Endeavour on Monday (Feb. 27) at 1:45 a.m.

During a post-FRR briefing on Tuesday evening, SpaceX and NASA representatives said the extra day would allow launch teams to fix a few minor issues with Endeavour and the Falcon 9.

Steve Stich, NASA's Commercial Crew Program manager, said team members want to study Endeavour's "pod panels"' thermal performance. The Falcon 9's composite overwrapped pressure vessels (COPVs)—helium bottles in the liquid-oxygen tank—are also interesting.

At Tuesday's briefing, Stich discussed the work on the COPV, adding, "We have discovered that there was mixing done in certain spots on the liner."

The teams found an issue in a Falcon 9 that launched a large batch of SpaceX's Starlink internet satellites. "There was a little bit of evidence of some combustion" in one rocket engine bay, Stich said, but the Starlink mission was successful. The Crew-6 team checks the other rocket for a combustion issue before the astronaut launch.

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Stich noted that Crew-6 would use a new rocket while Starlink's Falcon 9 first stage flew 12 times. SpaceX and NASA still analyze all Falcon 9 flights before crewed missions.

After this work, NASA and SpaceX expect Endeavour and its rocket to launch.

"I don't believe those items will be a worry for the crew trip," said Bill Gerstenmaier, vp of build & flight reliability for SpaceX, during the post-FRR briefing. “But we don't assume things for granted. We want to ensure they're truly ready.”

Crew-6 will carry NASA astronauts Stephen Bowen and Woody Hoburg, UAE's Sultan Al-Neyadi, and Russian cosmonaut Andrey Fedyaev to the ISS for six months. Al-Neyadi will be the first Arab astronaut to undertake a long-duration orbiting lab mission.

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Crew-6 will be SpaceX's sixth NASA-operated manned trip to the ISS. In addition to those six, Elon Musk's business has launched two more crewed trips to the orbiting lab: NASA's 2020 Demo-2 test flight and Houston startup Axiom Space's April 2022 Ax-1.

Endeavour flew Demo-2, Ax-1, and Crew-2, launched in April 2021, to the ISS.

The Crew-5 capsule Endurance is docked to the ISS. The four Crew-5 space flyers—NASA astronauts Josh Cassada and Nicole Mann, Japan's Koichi Wakata, and cosmonaut Anna Kikina—are slated to return to Earth five days after welcoming Crew-6 to the station.

Cassada, Mann, Wakata, and Kikina share the ISS with cosmonauts Sergey Prokopyev, Dmitry Petelin, and NASA's Frank Rubio, who arrived on a Russian Soyuz ship in September.

Prokopyev, Petelin, and Rubio were due to return to Earth on the same Soyuz next month, but they'll linger aloft until late September. On December 14, their Soyuz leaked all its coolant into orbit. Russia will launch a new Soyuz on Thursday (Feb. 23.)