NASA astronauts Sunita Williams and Butch Wilmore, who took part in Boeing Starliner’s inaugural crewed flight test in June, are set to come back to Earth. They return after spending a prolonged duration on the International Space Station (ISS), originally planned for a 10-day mission. Technical problems with the Starliner capsule caused the delay, and now they will be returning along with the Crew-9 team. Their exit is directly related to the forthcoming Crew-10 mission by SpaceX, which will replace Crew-9 on the ISS.

Crew-10, with four astronauts aboard, is set to lift off on March 12 at 7:48 p.m. EST from the Kennedy Space Center in Florida on a SpaceX Falcon 9 rocket. The flight was originally scheduled for February but was pushed back to March to give the mission more preparation time. The Crew-10 astronauts will relieve Crew-9 so that Williams and Wilmore can come back to Earth with the Crew-9 crew.

Once Crew-10 docks at the ISS successfully, Williams and Wilmore will leave the station with Crew-9, concluding their long-duration mission. However, their return will not be synchronized with the arrival of Crew-10. NASA has not yet confirmed the final departure schedule, but Wilmore has put forth a possible return date of March 19 on a preliminary basis, subject to NASA’s formal confirmation.

Williams and Wilmore flew on Boeing’s Starliner capsule in June for its initial crewed flight test. The mission was initially scheduled as a 10-day visit to the ISS but was unexpectedly delayed by technical problems. In particular, NASA reported issues with helium leaks and the propulsion system, which resulted in the mission being extended.

Against the backdrop of technical challenges, NASA decided to make a change in plan: Starliner was going to be back to Earth unmanned. The spacecraft landed safely on its own in New Mexico in September, preserving the astronauts’ safety as the engineers solved the technical problem in the spacecraft.

In August, NASA updated its return schedule for Williams and Wilmore, deciding to have them return on a SpaceX Dragon capsule rather than Starliner. This Dragon spacecraft had been delivered to the ISS on the Crew-9 mission in late September. To prepare for the return of Williams and Wilmore, Crew-9 was flown with only two astronauts, with two empty seats reserved for their eventual return.

As opposed to the Starliner, which was first scheduled for return, the SpaceX Dragon capsule can accommodate up to four astronauts. It had to stay at the ISS, awaiting the right time to bring the astronauts back following the successful arrival of Crew-10.

Before Williams and Wilmore can leave, Crew-10 has to first arrive at the ISS first. The mission’s docking process will occur early in the morning after the launch on March 12. After Crew-10 is on board safely at the ISS, Williams and Wilmore will be readying their return trip. While NASA has not announced a specific return date, it is indicated that Williams and Wilmore might leave on March 19.

The return schedule for them, however, will be based on the completion of Crew-10’s mission and then accordingly the release date will likely be announced coordinating for the safe exit of the Starliner astronauts.