The hydraulic problem that kept the next International Space Station (ISS) crew on the ground this week was likely due to trapped air in the system.
NASA [confirmed](https://www.nasa.gov/blogs/commercialcrew/2025/03/13/nasa-spacex-prepare-for-march-14-crew-launch-to-space-station/) the issue had been resolved on the eve of the second attempt to launch the Crew-10 mission from Launch Complex 39A at NASA's Kennedy Space Center in Florida.
The first attempt [was scrubbed](https://www.theregister.com/2025/03/13/starliner_duo_get_bonus_days/) at approximately T-44 minutes on Wednesday, March 12, when engineers could not clear an issue with the ground support hydraulics system used for the clamp arm supporting the SpaceX Falcon 9 rocket. Managers opted to scrub the launch before the crew access arm was retracted and propellant loaded.
A second launch opportunity on Thursday, March 13, was skipped owing to weather concerns, which also gave engineers more time to work on the problem with the hydraulics. According to NASA, SpaceX ground teams completed the system inspections and successfully flushed a suspected pocket of trapped air, clearing the issue ahead of the next scheduled launch attempt.
Steve Stich, manager of NASA's Commercial Crew Program, paid tribute to the NASA and SpaceX teams responsible for identifying and resolving the problem.
"I'm especially proud of the team's systematic approach throughout the countdown, analyzing data and making thoughtful decisions to ensure the integrity of our mission. Their commitment to both excellence and safety is a true testament to the strength of this integrated team," he added.
NASA is now targeting 1903 EDT on Friday, March 14, for the launch, and the current forecast puts the chances for favorable weather at more than 95 percent. The situation will go downhill if there is another scrub; the chance of weather violations rises to 50 percent and 60 percent on Saturday and Sunday, respectively.
If all goes to plan, the Crew-10 mission, which consists of NASA astronauts Anne McClain and Nichole Ayers, JAXA astronaut Takuya Onishi, and Roscosmos cosmonaut Kirill Peskov, is expected to arrive at the ISS on Saturday, March 15, around 2330 EDT. The four will spend a few days settling in before Crew-9 departs, along with Boeing's Starliner test pilots Suni Williams and Butch Wilmore, who have been on an extended stay aboard the ISS. The undocking of the Crew-9 spacecraft is planned for no earlier than Wednesday, March 19. ®