Advanced training for astronauts who are training for space missions can mostly be found at the Lyndon B. Johnson Space Center in Houston, Texas. They train for all aspects of space flights, from the flight itself, to work on the International Space Station, adding new components or delivering supplies to it, to launching commercial, military or government agency satellites into Earth orbit. The pre-mission training is heavy on studying the spacecraft, the mission and any other aspect of the Space flight. Astronauts are required to train not only for their own specific tasks, but each specialist should be capable of performing all tasks required and mandated for their mission at the end of the extensive training period.
Astronauts go through every aspect of the Space Shuttle's components, and the specialists must be able to perform each other's assigned tasks. Most of the work that these specially chosen few do while training for their specific missions is done either on simulators or in huge water tanks, doing their work under water, to more precisely mimic the restrictions on personal movement in space. When involved in advanced mission training, astronauts and specialists have to learn the work of the other astronauts as well, so that if problems occur, there will be someone capable of doing required tasks assigned to the stricken crew member(s).
Other than the astronauts who go into space for their missions, there are an equal number of specialists of equal rank that can help the astronauts in space by going into the simulators and trying to work out solutions to emergency problems that occur during space flights. This second team trains with the mission team during advanced mission training, and learn the exact same things, becoming capable of replacing any team members that may not be able to go on the mission for health or other reasons.
Astronauts are generally the most experienced and skilled pilots from the various branches of the military, but other specialists can and are chosen for different missions with regards to their expertise. Depending upon the mission statement, or the purpose of the space flight, the Space Shuttles that are currently in use, and scheduled for retirement after 2010, can hold up to seven astronauts and two mission specialists. The specialists can be anyone from a geophysicist studying rocks to a school teacher, and their studies mostly concern the effects of zero-gravity on seeds, insects and other subjects, like learning basic Russian when interacting with cosmonauts.
The advanced mission training usually consists of at least eight weeks of intense simulator training, where the events of an entire mission can be reproduced. The astronauts train in correcting every conceivable error, which are initiated by the simulator instructors, and the astronauts need to make the necessary repairs within specified time limits. Each member of each crew must be able to work in tandem, and as new errors or problems are encountered, each has to be added to the consequences of each of the other problems.
In order to know the work-arounds and repairs, the astronauts must, as they say, know their spacecraft and their mission inside and out. Only extensive training can accomplish this.