Astronaut Tim Kopra, scheduled to fly to the International Space Station (ISS) on the Shuttle Discovery, was injured today (Saturday) in a bicycle accident. NASA is citing medical privacy issues, and will not confirm the nature of Kopra's injuries, but I have it on good authority that Kopra broke his hip in the accident.
Kopra is the Flight Engineer for Discovery, with primary responsibilities during launch and reentry. Further, Kopra is is the lead spacewalker for this assembly mission to the ISS.
NASA no longer trains backup crews. Even a veteran astronaut would have great difficulty getting up to speed on the details of the ISS assembly spacewalks in the time available before launch.
Discovery was originally slated to launch in early November, but has been grounded as technical problems are being addressed.
Between broken ribs on the Shuttle External Tank, and the reported broken hip, Discovery has not had an easy path to orbit.