It is no surprise that astronauts undergo rigorous, lengthy training to do their jobs. They join the Astronaut Corps, usually as pilots or mission specialists, but then what? When do they go into space? How much time do they spend in space?

The truth is, an astronaut's time is spent in far more training and preparing to go into space than is actually spent in space. An astronaut's time is largely spent in the simulator and in other training arenas, if they are slated for the upcoming mission.

As the U.S. space program stands right now, the Space Shuttle is the only means of launching humans into space, so an astronaut’s time in space depends on how often the Shuttle is launched and what missions it is slated to perform. Will it dock with the International Space Station or will it be primarily a science mission? All these factors help decide which astronauts will be slated to fly on which missions.

Astronaut pilots, for example, will probably go on one or two missions to train as co-pilots before they are named the pilot of the Space Shuttle. Pilots are also selected depending on how much flight experience they have had, whether they have been test pilots, and how much time they’ve already spent in space.

An astronaut's time is spent between missions preparing for the next one. They work in large dive tanks that mimic weightless conditions, in order to learn how to perform spacewalks. Spacewalks are often used for repair missions on the International Space Station, the Hubble Telescope or on the Shuttle itself.

A pilot astronaut's time is spent in intensive training involving flying modified business aircraft that mimic the Shuttle's flying characteristics. The orbiter approaches the runway at a steep angle and at over 300 miles per hour (483 kilometers per hour), so pilots need to learn how to land an orbiter whose characteristics are so different even from a jet fighter.

Because of the limited number of Shuttle missions, much of an astronaut's time is spent on the ground. Some NASA analysts estimate the average wait time between qualification and first space mission is 105 months. With the Space Shuttle being phased out of service, this time could stretch into a much longer wait, unless NASA decides to pare down the Astronaut Corps and not train more candidates until the agency has a more regular mission schedule in place.