NASA and SpaceX on Friday will count down to a long-awaited crewed rocket launch that will allow them to bring home U.S. astronauts Butch Wilmore and Suni Williams, who have been stuck on the International Space Station for nine months.

Now that SpaceX ground teams have “successfully flushed a suspected pocket of trapped air” in the ground support hydraulics system used for the clamp arm supporting the Falcon 9 rocket, there will be another attempt to launch the Crew-10 mission to the ISS tonight,

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.