John M. Grunsfeld, a former NASA astronaut who logged more than 58 hours on spacewalks during three missions to repair and upgrade the Hubble Space Telescope, has been named deputy director of the Space Telescope Science Institute in Baltimore. Grunsfeld, who holds a doctorate in physics and specializes in X-ray and gamma-ray astronomy and high-energy cosmic ray studies. In a statement, he called his new job "an incredibly exciting opportunity for me to work at a focal point of top astronomers at the leading edge of scientific inquiry." The institute is the science operations center for the Hubble telescope, and for the James Webb Space Telescope, which is slated for launch in 2014. Grunsfeld, 51, joined NASA's astronaut corps in 1992. He flew five space missions in all, logging more than 835 hours in orbit.