NASA has named physicist and former astronaut John Grunsfeld as the new associate administrator for the Science Mission Directorate at the agency's headquarters in Washington. Grunsfeld will take the reins of the office effective Jan. 4, 2012. He succeeds Ed Weiler, who retired from NASA on Sept. 30. Grunsfeld currently serves as the deputy director of the Space Telescope Science Institute in Baltimore, which manages the science program for the Hubble Space Telescope and is a partner in the forthcoming James Webb Space Telescope.

His background includes research in high energy astrophysics, cosmic ray physics and in the emerging field of exoplanet studies with specific interest in future astronomical instrumentation.

A veteran of five space shuttle flights, Grunsfeld visited Hubble three times as an astronaut, performing a total of eight spacewalks to service and upgrade the observatory.

"John's understanding of the critical connection between scientific research and the human exploration of space makes him an ideal choice for this job," NASA Administrator Charles Bolden said.

"I look forward to working with him to take the agency's science programs to even greater heights and make more of the ground-breaking discoveries about Earth and our universe for which NASA is known."

Grunsfeld graduated from the Massachusetts Institute of Technology in 1980 with a bachelor's degree in physics. Returning to his native Chicago, he earned a master's degree and, in 1988, a doctorate in physics from the University of Chicago using a cosmic ray experiment on space shuttle Challenger for his doctoral thesis.

From Chicago, he joined the faculty of the California Institute of Technology as a Senior Research Fellow in Physics, Mathematics and Astronomy.

Grunsfeld joined NASA's Astronaut Office in 1992. He logged over 58 days in space on five shuttle missions, including 58 hours and 30 minutes of spacewalk time. He first flew to space aboard Endeavour in March 1995 on a mission that studied the far ultraviolet spectra of faint astronomical objects using the Astro Observatory. His second flight was aboard Atlantis in January 1997.

The mission docked with the Russian space station Mir and exchanged U.S. astronauts living aboard the outpost. Grunsfeld then flew three shuttle missions - aboard Discovery in December 1999, Columbia in March 2002, and Atlantis in May 2009 - that successfully serviced and upgraded the Hubble Space Telescope.

He served as the payload commander on the 2002 mission and lead spacewalker in charge of Hubble activities on the 2009 flight. In 2004 and 2005, he served as the commander and science officer on the backup crew for Expedition 13 to the International Space Station.

"It is an honor and a privilege to be offered the opportunity to lead NASA's Science Mission Directorate during this exciting time in the agency's history," Grunsfeld said. "Science at NASA is all about exploring the endless frontier of the Earth and space. I look forward to working with the NASA team to help enable new discoveries in our quest to understand our home planet and unravel the mysteries of the universe."