A multi-national crew of astronauts staffs the International Space Station. Photo Credit/NASA TV.

NASA will formally seek astronaut applicants in November, with plans to hire its first post-shuttle era class in 2013 and start their training regime in August of that year.

The agency did not say how many new astronauts it intends to hire in an announcement fon Monday. But earlier this summer, Chief Astronaut Peggy Whitson estimated it could be in the “four to six” range. Once past the training phase, the newest NASA astronauts would be assigned aboard new spacecraft under development for voyages to deep space destinations as well as long duration missions to the International Space Station.

“For scientists, engineers and other professionals who have always dreamed of experiencing spaceflight, this is an exciting time to join the astronaut corps,” said Janet Kavandi, NASA director of flight crew operations, which supervises the astronaut corps.

The agency currently counts 61 astronauts eligible for flight assignments, down from a high of 139 fliers in 2000, when NASA was launching five to six shuttle missions annually and beginning to staff the space station. Another 43 astronauts now fill management positions and are not considered eligible for flight.

The shuttle fleet was retired in January, as the assembly and outfitting of the station drew to a close.

Under a tentative timeline, the application process would close on Jan. 13, 2012. From March through October, the agency would review the qualifications of applicants and narrow the number invited for interviews and further medical evaluation. The selection class would be announced in March 2013.

In this illustration NASA's Orion/Multi-Purpose Crew Vehicle closes in to dock with another spacecraft. Photo Credit/NASA illustration

NASA hired nine of 3,500 applicants in 2009, its most recent astronaut class The six men and three women averaged 37 years of age and have backgrounds as military test pilots, scientists, engineers and medical doctors.

A bachelor’s degree in engineering, science or math and three years of relevant professional experience are required in order to be considered. Typically, successful applicants have significant qualifications in engineering or science, or extensive experience  flying high-performance jet aircraft.

NASA offers more information about astronaut selection at : http://astronauts.nasa.gov/