By Joey Roulette (Reuters) -SpaceX on Wednesday scrubbed the expected launch of a replacement crew of four astronauts to the International Space Station that would have set in motion the long-awaited homecoming of U.

It's possible SpaceX attempts another launch on Thursday, which would pave the way for the astronauts to return to earth.

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.