NASA is recruiting up to 15 new astronauts to bolster the agency's corps of space fliers to staff the International Space Station and lay the groundwork for exploration missions beyond Earth, agency officials announced Tuesday.

Between 9 and 15 astronauts will be selected in early 2013, but the deadline to apply is Jan. 27, 2012.

"We are looking for the most qualified people we can get to be part of this elite corps," said Janet Kavandi, chief of flight crew operations at NASA's Johnson Space Center in Houston. "It is not an easy process to be selected."

Those interested in becoming an astronaut can read the posting and apply online on the USAJobs.gov website.

Requirements for the position include a bachelor's degree in engineering, biological science, physical science, or mathematics, and at least three years of related, progressively responsible work experience.

Pilots who meet the same degree requirements can meet NASA'a astronaut candidate standard with at least 1,000 pilot-in-command hours in jet aircraft in lieu of research experience.

Applicants must also have vision correctable to 20/20 in each eye, blood pressure not above 140/90 in a sitting position, and a height between 62 inches and 75 inches.

Candidates selected in 2013 will undergo about two years of intense robotics, spacewalk, flight and survival training before being eligible for space missions.

NASA Administrator Charlie Bolden said Tuesday the next class of astronauts could fly to the space station on U.S.-built commercial vehicles and explore beyond low Earth orbit with the agency's Orion spaceship and heavy-lift rocket.

For now, NASA astronauts' only ride into orbit is Russia's Soyuz spacecraft.

The space agency inducted nine new members into its astronaut corps earlier this year. The newest astronauts were selected in the 2009 class.

A government-sponsored study by the National Research Council releaesed in September recommended NASA increase the margin in its staffing predictions, concluding the current size of the astronaut corps "cannot fully account for uncertainties, such as retirements and astronauts who may experience temporary or permanent medical disqualifications."

"With the retirement of the shuttle program and the uncertainty during the transition to a fully operational ISS, it's even more important that the talent level, diversity, and capabilities of the astronaut office be sustained," said Joe Rothenberg, co-chair of the NRC committee, when the report was released Sept. 7.

The NRC report also highlighted more rigorous and lengthy training required for space station expeditions. Astronauts are typically selected for a flight two or three years before launching a long-duration stay on the space station.

"Viewed as a supply chain, astronaut selection and training is very sensitive to critical shortfalls; astronauts who are trained for specific roles and missions can't be easily interchanged," said Fred Gregory, a former space shuttle commander who co-chaired the NRC study.

The NRC report also urged NASA to retain its fleet of two-seat T-38 jet trainers in the post-shuttle era.