Beginning with selection of the first astronauts in 1959 before human spaceflight operations began, NASA asked the military services to provide a list of personnel who met specific qualifications. After stringent screening they selected seven men, all pilots, as the first American astronauts.

Since then some 3,500 men and women have gone through the lengthy and rigorous training and NASA has admitted only 330 astronauts.

With the return to Earth of Atlantis STS-135, the final space shuttle, the U.S. manned space program has been parked along with the shuttles. This represents the first time in 50 years that there are no planned manned missions out of Earth’s atmosphere.

NASA has a robust program of exploration, technology development and scientific research planned, but in the near future the only way to get to the International Space Station will be to hitch a ride on a Russian Soyuz rocket at $62 million per seat.

That does not mean that U.S. manned space travel is finished.

NASA is designing and building the capabilities to send humans to explore the solar system, working toward a goal of landing humans on asteroids and Mars, but Earth orbit and moon landings are not on the menu.

NASA is no longer the only game in town for astronaut training. A new class of citizen astronauts recruited, trained and employed like airline pilots have the potential to create the first ever private astronaut corps and provide flight opportunities for the 60 or so NASA astronauts left high and dry when Congress mandated the end of the shuttle fleet.

More than 20 private companies are poised to send human cargo into near earth orbit, including Boeing and newer companies such as SpaceX and Bigelow Aerospace. This 21st century collection of companies has bid for hundreds of millions in NASA grant money to develop launch and orbital vehicles.

NASA plans to start sending astronauts to the space station on private flights by 2015, while other companies are focusing on suborbital recreational flights that provide several minutes of weightlessness and spectacular vistas of Earth’s curvature from 60 miles up.

In July the inaugural class of privately owned Astronauts for Hire completed training for upcoming suborbital spaceflights. FAA requirements stipulate that candidates must pass the same medical exam given to commercial airline pilots, but companies will be looking for eclectic backgrounds to reflect the variety of space vehicles under development.

Whether few or several companies come to employ astronauts of the future, the role and image of astronauts will change as flights become routine and astronaut pilots become more blue collar like today’s 18-wheel jockeys. No matter what the eventual outcome of extraterrestrial travel, future daredevil explorers in the image of the NASA pioneers will need to have the right stuff.