The first step to being an astronaut is getting relevant experience in school. There are two main classes of astronaut applicants: military applicants and civilian applicants. Military application procedures vary depending on the branch of the U.S. armed forces you are working for, since you apply through your respective branch. Civilians apply to NASA directly.
No matter the background, NASA wants its astronauts to have at least a bachelor's degree in engineering, biological science, physical science or mathematics. (The agency maintains a list of exceptions to these degrees, such as geography or aviation management.) Many astronauts have a master's degree or even a Ph.D. in their field. Some astronauts, such as Story Musgrave (now retired), have degrees even beyond that.
It takes more than school to gain a foothold as an astronaut selection candidate, however. NASA wants at least three years of "related, progressively responsible, professional experience" or (in a nod to military candidates) at least 1,000 hours of "pilot-in-command time in jet aircraft." Advanced degrees are considered equivalent to this experience, however, with a master's equaling one year of experience and a doctorate three years of experience.
A notable exception to these requirements are teachers, who still must have a technical bachelor's degree but can qualify through the act of teaching — even for elementary school children.
NASA astronaut candidates must also pass a demanding physical. Among the requirements:
- 20/20 vision (either naturally or with corrective lenses)
- blood pressure not more than 140/90 in a sitting position
- a height of between 62 and 75 inches
In general, you must be in extremely good shape to be an astronaut as it's expensive to make an emergency return to Earth in case of medical emergency in orbit.
There also are interviews during the selection process to figure out if a candidate is physically and psychologically able to work as an astronaut. Flexibility, group work skills and a love of learning are some of the personality traits NASA looks for.
Once selected, NASA does not consider you to be a full astronaut yet. There are two years of basic training ahead in which you are considered an "astronaut candidate." The candidates receive basic classroom learning about the International Space Station and spaceflight generally. They also become qualified scuba divers, do military water survival training, undergo swimming tests, are exposed to high and low atmospheric pressures, do flights in the "vomit comet" and get media and Russian language training, among other things.
Once an astronaut is selected for a flight, the mission training takes another couple of years. They start by reading textbooks and receive classroom training, then do simulation after simulation to learn the stuff for real. Their training takes place all over the world, both individually and with their crewmates.
A typical spaceflight these days for a NASA astronaut lasts six months on the International Space Station, but some astronauts are now being assigned to year-long flights to learn more about the human body. Science will take up most of an astronaut's time in orbit.