The return of the Boeing Starliner spacecraft to Earth has been delayed

The return of Boeing's Starliner spacecraft to Earth has been delayed again.

The US space agency said Tuesday (June 18) that the spacecraft undocked from the International Space Station no earlier than June 25 US Eastern Time, Xinhua reported.

The first manned test flight of Boeing's "Starliner" spacecraft (CST-100 Starliner) took off on June 5 with two American astronauts and flew to the International Space Station on June 6. It was scheduled to leave the International Space Station and return to Earth on Friday (14), but the return time has been repeatedly delayed.

The U.S. space website reported Tuesday that a propeller failure was one of the reasons for the delay. NASA and Boeing are evaluating a problem with the Starliner's thrusters during its first attempt to dock with the International Space Station, when some of them briefly failed.

The Starliner also suffered helium leaks several times during manned test flights. The two astronauts on board the Starliner have been testing the spacecraft's various systems in orbit, and ground teams are continuing to analyze data to better deal with thruster failures and helium leaks, Space said.

According to the US space website, the spacewalk schedule of the International Space Station is also one of the reasons for the delayed return of the Starliner. Two US astronauts stationed on the International Space Station were scheduled to carry out a spacewalk on the 13th, after one astronaut complained that the spacesuit was "uncomfortable". The spacewalk has been postponed until the 24th.

The crewed Starliner test flight, originally scheduled for May 6, has been delayed several times for technical reasons. At the end of this mission, NASA will make final certification for Starliners to carry out routine commercial crew missions and regularly ferry astronauts to and from the International Space Station.