Washington, Nov 17 (IANS): America's space organisation NASA has launched a massive recruitment drive to find new astronauts, despite not having its own spaceship for them to fly.

With its shuttle fleet retired, many veteran astronauts are now reportedly leaving the organisation, Sky News reported.

While Atlantis, Discovery, Endeavour and Enterprise were retired in 2011, Challenger disintegrated in 1986 and Colombia in 2003.

And NASA is now worried it will not have enough astronauts for future projects.

The NASA website has an advertisement that says: "Want a career that'll take you full circle? Adventure. Commitment. Leadership. Achievement. Apply to explore with us. Fly NASA, where the sky is not the limit. NASA is going places where there are no boundaries. Your unique talents and experiences can take you there too."

American astronauts are now taking part in other countries' space missions.

An astronaut recently gone to the International Space Station (ISS) after flying there on board Russia's Soyuz spaceship.

Reports say that in about three to five years, NASA hopes to purchase trips for astronauts on US-built commercial rockets.

And eventually it hopes to fly astronauts in a US government-owned Orion capsule to an asteroid or even Mars. But those trips may not happen for more than a decade.

To get a job as an astronaut, a person needs a bachelor's degree in engineering, science or maths and three years of professional experience.