Now that Butch Wilmore and Suni Williams are home, ending a 9-month spaceflight, questions remain about the troubled Starliner they rode to orbit.

Wilmore and Williams, both former U.S. Navy test pilots, expected to remain in orbit for about 10 days on the mission, which was called Crew Flight Test (CFT). The main goal was to show that Starliner is ready to carry astronauts to and from the ISS, so that the spacecraft can start flying operational, long-duration missions in the near future.

NASA and SpaceX made another attempt on Friday to send a crew up to the International Space Station (ISS) and begin the return of a pair of astronauts.