John Mace Grunsfeld
John Mace Grunsfeld is an American physicist, five-flight shuttle astronaut, Hubble Space Telescope repair astronaut, and former NASA science leader. His career sits at the intersection of astrophysics, hands-on spacecraft servicing, and agency-level science management.
- Born
- October 10, 1958
- Died
- N/A
- Birthplace
- Chicago, Illinois,United States
Flights
5
Spacewalks
8
EVA time
58 hours, 30 minutes
In space
58 days, 15 hours, 3 minutes
Bio
Grunsfeld studied physics at the Massachusetts Institute of Technology and the University of Chicago, then worked in high-energy astrophysics and cosmic-ray research. That science background shaped his NASA role, where he became one of the astronauts most closely associated with astronomical observatories.
He flew STS-67 and STS-81 before becoming a central figure in Hubble servicing. On STS-103, STS-109, and STS-125, Grunsfeld performed multiple to repair and upgrade the Hubble Space Telescope, helping preserve one of NASA's most productive scientific instruments.
After flight service, Grunsfeld held senior science roles, including work at the Space Telescope Science Institute and leadership of NASA's Science Mission Directorate. His postflight career kept him connected to the same scientific community served by the telescope he helped maintain.
Grunsfeld's biography needs to feel bigger than a mission list: he is a scientist-astronaut whose EVA work directly extended Hubble's life and whose later NASA leadership shaped planetary, astrophysics, and Earth-science programs.