Grunsfeld is training for an astronaut assignment to a long duration mission, the specifics of which will be announced at a later date. He will also provide expert support and counsel to NASA's Astronaut Office. Grunsfeld was appointed NASA's Chief Scientist in Sept. 2003. He has been supporting Administrator O'Keefe at in Washington directing NASA's space-based science objectives and ensuring the scientific merit of agency programs.

"John's extensive background in physics and astronomy, together with his unmatched hands-on experience in conducting science operations in space, made him the ideal advisor to steer agency science decisions during his management tenure in Washington," Administrator O'Keefe said. "His unique skills will be sorely missed here, but I know he will continue to provide his valuable input to the decision process from his Johnson Space Center vantage point as well."

Garvin, who earlier this year announced the Mars Exploration Rovers had found strong evidence liquid water once existed on the martian surface, will work to ensure the scientific merit of NASA's programs, including those embracing exploration.

"Jim was instrumental in this most recent round of successful Mars exploration," said Administrator O'Keefe. "He played a critical role in decisions ranging from whether the rovers should fly to Mars and where they should land, to their overall science strategy on the martian surface. His experience and extensive knowledge of agency operations will help us pursue the programs with the most scientific merit and relevance, as we move forward with the Vision for Space Exploration."

Grunsfeld is a veteran of four Space Shuttle flights and five successful spacewalks to upgrade the Hubble Space Telescope (HST).

Grunsfeld received a bachelor's degree in physics from the Massachusetts Institute of Technology in 1980. He earned a masters degree and a doctorate in physics from the University of Chicago in 1984 and 1988, respectively.

Grunsfeld was honored with the W.D. Grainger Fellow in Experimental Physics and awarded the NASA Exceptional Leadership Medal earlier this year. He received NASA Space Flight Medals in 1995, 1997, 1999 and 2002, and the agency's Exceptional Service Medal in 1997,1998 and 2000.

Garvin is currently in charge of formulating scientific requirements for NASA's missions for studying Mars and the moon. His primary areas of scientific specialty include laser altimetry of terrestrial and planetary landscapes; geology of impact craters relevant to exploration of the moon and Mars; and sedimentology on Mars, Earth and Venus. He was chief scientist for the Shuttle Laser Altimeter flights aboard Endeavour (STS-72) and Discovery (STS-85).

Garvin joined the Geodynamics Branch at NASA's Goddard Space Flight Center in 1984. He led a team of engineers and scientists that developed the first orbiting laser altimeter instruments for quantifying the three-dimensional characteristics of landscapes on the Earth and Mars. After the Challenger accident in 1986, Garvin served as a scientist on astronaut Sally Ride's leadership team.

Garvin has served as a member of the science team for Mars Global Surveyor, Mars Observer and NASA airborne laser topographical surveys of dynamic landscapes in Iceland. He was Project Scientist for the Earth System Science Pathfinder program, which studies the Earth's oceans, clouds, interior and the aspects of the chemistry of the atmosphere.

He was as a member of the international science team for Canada's RADARSAT mission, science team member on the European Space Agency ENVISAT mission, and a science team member on the Near Earth Asteroid Rendezvous Shoemaker mission.

Garvin received his bachelor's degree in applied math/computer sciences from Brown University, Providence, R.I. in 1978; a master's in computer science from Stanford University, Stanford, Calif., in 1979; master's in geological sciences from Brown in 1981; and a Ph.D. in geological sciences from Brown in 1984. He was awarded Brown's William Rogers Award this year for his outstanding contributions to society.

Garvin was awarded NASA Outstanding Leadership Medals for his role in defining the scientific strategy for NASA's Mars Exploration Program, and for his contribution to the scientific success of the Mars Exploration Rover mission. He is a fellow of the Explorers Club and a member of the American Geophysical Union. He has published more than 60 research articles, numerous abstracts and reports.