Would-be US astronauts have to undergo rigorous training and stringent selection procedures if they want to join an elite body of just 135 people, mostly men, and journey to the stars. With more than 4,000 applicants chasing just 20 places available every two years, competition is tight and the National Aeronautics and Space Administration (NASA) sets tough standards for the physically and mentally challenging job.
"The astronauts of the 21st century will help lead NASA through the next steps of its 'Vision for Space Exploration' as we explore the Moon, Mars, and beyond," NASA says in its careers section on its website.
Air Force and Navy pilots as well as aeronautical engineers are in high demand, but top scientists can also be called upon to be mission specialists, with NASA stressing that people with a wide range of experience such as teachers and microbiologists can also play vital roles.
Only US citizens can apply through the NASA program and although there is no age limit, the average age is around 34 years old.
The minimum requirement to be a pilot astronaut is a bachelor's degree in engineering, science or mathematics from an accredited institution.
Three years of related experience must follow and an advanced degree is desirable. Pilot astronauts must also have at least 1,000 hours of experience in jet aircraft, and they need good eyesight.
All applicants have to be in tip-top physical health and are required to undergo a strict medical exam. The must be between 5 feet 4 inches (1.6 meters) and 6 feet 4 inches (1.9 meters) tall.
Once chosen, the applicants follow physical and theoretical training at the Johnson Space Center in Houston, Texas, which lasts between 18 months to two years, and lays the groundwork for complex space missions such as on the International Space Station.
In a stranger-than-fiction story Tuesday, a US astronaut was facing an attempted murder charge after trying to kidnap and assault a NASA employee she believed was her rival in a love triangle.
Lisa Nowak, 43, who is married with three children and based at the Houston center, was charged a day after being arrested for assaulting her alleged love rival, Colleen Shipman, at Orlando International Airport.
Nowak, who flew on a shuttle Discovery mission to the International Space Station in July, believed Shipman was also involved with astronaut William Oefelein, 41, who flew a mission to the orbiting space station in December.
