- In any moment of decision, the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing. Theodore Roosevelt
Become an Astronaut
Astronauts are people who do activities related to human space exploration. The most visible parts of their job take place while they're working in orbit, but most of their careers will be spent on the ground training and supporting other missions.
Becoming an astronaut doesn't just happen overnight. It takes many years of education and experience to meet the basic qualifications. Many people aren't accepted on the first try, either, requiring them to learn more to be better prepared for the next try. Even then, only a small percentage of applicants become astronaut candidates, making it a hard job to get.
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.
Astronaut candidacy and path to flight
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.
After graduating, many astronauts are not assigned to a flight for years. They will back up other astronauts in orbit through serving as a "CapCom" in Mission Control, doing simulated spacewalks in NASA's Neutral Buoyancy Laboratory and picking up more skills they will need for their time in orbit. They spend time not only at NASA, but also international partners with training facilities.
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.