"John has a deep interest in astronautical science and has the hands-on experience to back up what he has taught in the classroom," O'Keefe said.

"With his background in physics and astronomy, John is a natural selection to direct NASA's important space-based science objectives."

Grunsfeld replaces Shannon Lucid, a fellow astronaut, who returns to the Johnson Space Center in Houston, Texas, to assist in returning the US space shuttle fleet to orbit.

Shuttle flights have been suspended since the shuttle Columbia broke up on re-entry February 1.

SPACE.WIRE