Boeing’s Starliner spacecraft has successfully delivered two astronauts to the International Space Station, a key milestone in the aerospace giant’s quest to certify the capsule for regular crewed missions. 

Starliner safely docked at 10:34 AM Pacific Time. After taking some time to equalize pressure between Starliner and the station, the hatch opened at around 12:46 PM. The astronauts, spaceflight veterans Butch Wilmore and Suni Williams, entered the ISS to cheers and hugs from the seven crew members already aboard. This is their third time each visiting the station, but the first time any human has done so using a Boeing Starliner capsule. 

Boeing and NASA are currently in the middle of what will end up being a roughly 10-day test mission of the Starliner spacecraft, which has been beset by numerous delays and technical issues. The two astronauts will spend eight days on the ISS before re-boarding Starliner and returning home for a parachute-assisted landing somewhere in the southwestern United States.

Though successful, the mission was not without its problems. The vehicle experienced three helium leaks, one of which was identified before the spacecraft even left Earth, though Boeing says the leaks are not a safety issue for the crew or the vehicle. In addition to those, five of the 28 maneuvering thrusters on the spacecraft’s propulsion system failed, though Boeing and NASA were able to bring four of them back online after conducting hot-fire tests — essentially turning them off and on again. These thrusters are critical, as they make the minute shifts to the capsule’s trajectory as it approaches the station. 

The thruster problem forced the two astronauts to stop Starliner less than 1,000 feet from the ISS and put docking on hold. They were clear to dock a few hours later after troubleshooting the issue.

“Nice to be attached to the big city in the sky,” Wilmore said to Mission Control. “It’s a great place to be.”