NASA has announced it will start accepting applicants for its next class of astronaut candidates in November.

The last class of nine astronauts graduated in 2009, with the new class expecting to graduate in 2013.

NASA has said that the new class could participate in long-duration flights to the International Space Station and possibly even eventual exploration missions beyond low Earth orbit.

"For scientists, engineers and other professionals who have always dreamed of experiencing spaceflight, this is an exciting time to join the astronaut corps," Janet Kavandi, director of flight crew operations at the Johnson Space Center in Houston, said in a statement.

In order to be considered, applicants must have a degree in engineering, science or maths and three years of relevant professional experience. Applicants will be selected from both the civilian world and the military.

The news has arrived during uncertain times for NASA's human spaceflight programme. No US commercial vehicles are expected to fly to the station until at least 2015.

With the retirement of the space shuttle programme earlier this year, the number of astronauts fell to around 60 from nearly 150 in 2000.

Nonetheless, Janet Kavandi, director of flight crew operations at Johnson Space Center in Houston, called it "an exciting time to join the astronaut corps."

"This next class will support missions to the station and will arrive via transportation systems now in development," she said in a statement. "They also will have the opportunity to participate in NASA's continuing exploration programs that will include missions beyond low Earth orbit."

The new class will be the 21st selection by NASA since the Original Seven in 1959.