The Starliner spacecraft will depart the International Space Station on June 26

The first-ever Starliner mission aims to prove that this vehicle is safe to begin regular space taxi operations. Officials said in a press conference on Tuesday that astronauts Butch Wilmore (61 years old) and Sonny Williams (58 years old) will not return to Earth until June 26.

“We want our teams to have more time to check the data and do some analysis and make sure we're really ready to come back,” NASA's Steve Stich said. According to Boeing's Mark Nappi, the propellers now have a “good level of performance” and “leaks are stable and less significant.”

A big challenge for Boeing

The ship took off from Florida on June 5, years late and numerous last-minute postponements. If all goes well, it will depart the International Space Station on June 26 at 02:10 GMT for a scheduled landing in New Mexico, in the southwestern United States, at 08:51 GMT.

Its heat shield must withstand external heat, which can reach about 1650 degrees Celsius. This high-speed capsule return is the final crucial stage in this test mission.

The Starliner represents a major challenge for aerospace giant Boeing, which is also facing production quality problems at its commercial aviation subsidiary.

In 2014, NASA ordered two new vehicles from Boeing and Elon Musk's SpaceX to transport astronauts to the International Space Station. But if SpaceX has been playing this role as a space taxi for four years now, Boeing's program has seen many disappointments and fallen behind schedule.