An Astronaut Explores NASA's Scientific Frontiers

Apr 27, 2012
Originally published on April 27, 2012 12:47 pm

He's flown the space shuttle five times, and performed eight spacewalks to service the Hubble telescope. Now astronaut and astrophysicist John Grunsfeld heads up NASA's Science Mission Directorate, where he manages scientific investigations on the home planet--and beyond.