There's a ready and willing replacement waiting in the wings if NASA astronauts Bob Behnken or Doug Hurley can't make it on board the SpaceX Crew Dragon for its historic launch next week. Star Trek actor William Shatner has volunteered for the journey to the International Space Station. 

Shatner, famous for his role at Captain James T. Kirk, tweeted a photo of his face in a SpaceX spacesuit to NASA's attention on Wednesday. "Just in case; the suit does fit!" he wrote.