An astronaut is someone who is trained to operate or work aboard spacecraft. Many of these people work for government-sponsored space programs, although in the early 21st century, private firms began working in space as well. Astronauts are often figures of awe and admiration in their communities, and this adulation is well deserved; they endure grueling schedules and training programs for years before they are even allowed to go into space. They are also at the peak of physical fitness, and most are extremely intelligent.
Manned spaceflight began in Russia in 1961, when Yuri Gagarin was blasted in orbit by the Soviet space program. The United States quickly followed suit, and these two nations have dominated spaceflight historically, although citizens of several other countries have been into space as well. International cooperation between national space programs resulted in the foundation of the International Space Station in 1998. Russian astronauts are known as cosmonauts, although the two terms can be used interchangeably.
Because the area on a spacecraft is extremely limited, astronauts are cross-trained to perform a number of tasks. A pilot, for example, might also be trained to carry out scientific experiments, or to work on equipment repairs. In space, these professionals pilot their craft, conduct experiments, and observe the Earth from their unique point of view. They generally have an extensive knowledge of astronomy, physics, and other sciences, and they must also be good at working cooperatively with people in cramped spaces.
Training to become an astronaut is very demanding, and space programs only accept a limited number of people as trainees. Applicants must pass physical and psychological examinations and submit to regular exams to ensure that they stay fit for the job. These exams include stress tests to determine whether or not the candidate will be able to handle the unique conditions in space. A bachelor's degree and related experience are often required, along with experience piloting jet aircraft, if someone wants to become a pilot.
When someone is accepted for training, he or she will spend months at a training facility and in a variety of conditions that simulate the environment of space. These people actually spend most of their time on the ground, since seats on flights are very limited. National space programs occasionally allow special visitors to have seats on space flights, if those individuals can demonstrate that their inclusion will benefit the mission; these visitors must also endure the training.