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

Grunsfeld's research has covered x-ray and gamma-ray astronomy, high-energy cosmic ray studies, and development of new detectors and instrumentation.

His current research is in planetary science studying the moon Europa, and other solar system bodies in the search for life beyond Earth.

Grunsfeld was initially detailed to the Astronaut Office Mission Development Branch and was assigned as the lead for portable computers for use in space.

Following his first flight, he led a team of engineers and computer programmers tasked with defining and producing the crew displays for command and control of the International Space Station (ISS).

As part of this activity, he directed an effort combining the resources of the Mission Control Center (MCC) Display Team and the Space Station Training Facility.

In January 2012, he became the associate administrator for the Science Mission Directorate at NASA's headquarters in Washington, replacing Ed Weiler.

[11] His public lectures include Hugging Hubble at the Space Telescope Science Institute's May, 2010, Symposium,[12] Big Science Questions at the 50th anniversary celebration of the Aspen Center for Physics[13] and The Hubble Story presented as a special public lecture at Oxford University's department of physics.

The mission also carried the Spacehab double module providing additional middeck locker space for secondary experiments.

Following 160 orbits of the Earth the STS-81 mission concluded with a landing on Kennedy Space Center's Runway 33 ending a 3.9 million mile journey.

The mission also replaced a Fine Guidance Sensor, six new gyroscopes, and two battery unit modules, to allow the telescope to continue to function at least through 2014.

[22][23] One issue Grunsfeld and his crew experienced during the overhaul was the stripping of 10mm bolts due to improper assembly and technique which he discussed again on Car Talk.

[24][25] According to a NASA press release in January 2010, Grunsfeld indicated he would leave the agency to serve as deputy director of the Space Telescope Science Institute in Baltimore.

[28] Grunsfeld appeared on the PBS NOVA episode "Deadly Ascent", which showed him climbing Denali, the highest peak in North America, in June 2000.

Grunsfeld, along with Howard Donner, (a consultant to NASA) conducted research into the effects of body temperature at high altitudes by using internal thermometers swallowed in pill form.