The Boeing Starliner spacecraft successfully completed its uncrewed flight back to Earth, NASA announced overnight. The return ended the Starliner’s most recent flight test months later than intended and leaves its original crew, NASA astronauts Barry “Butch” Wilmore and Suni Williams, aboard the International Space Station until next year.

After their flight was scrubbed on Wednesday, four astronauts successfully lifted off, which will allow two NASA astronauts to return to Earth after an unexpected extended stay in orbit.

The $488 million Spherex mission aims to explain how galaxies formed and evolved over billions of years, and how the universe expanded so fast in its first moments.