A launch pad problem has forced a flight delay to replace NASA's two stuck astronauts. The new crew needs to get to the International Space Station before Butch Wilmore and Suni Williams can head home after nine months in orbit.

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.