How long does an astronaught have to be trained to go into space?

Answer 1

I found this on wikipedia after googling "astronaut"

"Once selected, NASA astronauts go through 20 months of training in a variety of areas, including training for extra-vehicular activity in a facility such as NASA's Neutral Buoyancy Laboratory.[1][55] Astronauts-in-training may also experience short periods of weightlessness in aircraft called the "vomit comet", the nickname given to a pair of modified KC-135s (retired in 2000 and 2004 respectively, and replaced in 2005 with a C-9) which perform parabolic flights.[54] Astronauts are also required to accumulate a number of flight hours in high-performance jet aircraft. This is mostly done in T-38 jet aircraft out of Ellington Field, due to its proximity to the Johnson Space Center. Ellington Field is also where the Shuttle Training Aircraft is maintained and developed, although most flights of the aircraft are done out of Edwards Air Force Base."