John Grunsfeld will be one of four spacewalkers who will go on the Hubble Space Telescope service mission scheduled for October.

Alumnus, astronaut will service Hubble Space Telescope on mission

This October, University alumnus and veteran astronaut John Grunsfeld will go to astronomical lengths to help refurbish the Hubble Space Telescope, the orbiting namesake of Edwin Hubble, another Chicago graduate.

Working at an altitude of 317 nautical miles, Grunsfeld will serve as one of four spacewalkers during the next Hubble servicing mission.

NASA originally had scheduled the mission for June 2000 but moved it to October so astronauts can begin to replace portions of the spacecraft’s pointing system, which has begun to fail.

“The Hubble Space Telescope is the crown jewel of NASA’s space observatories, and we need to do everything within reason to maintain the scientific output of this national treasure,” said Edward Weiler, NASA’s associate administrator for the Office of Space Science in Washington, D.C.

Hubble is operating normally and continues to conduct scientific observations, but only three of its six gyroscopes, which allow the telescope to point at the stars, planets and other targets, are working properly.

In addition to replacing all six gyroscopes on the 10-day October mission, the crew will replace a guidance sensor and the spacecraft’s computer. A voltage/temperature kit will be installed to protect spacecraft batteries from overheating. A new transmitter will replace a failed spare currently aboard the spacecraft, and a spare solid-state recorder will be installed to allow efficient handling of high-volume data.

Astronauts also will replace degraded telescope insulation, which controls Hubble’s internal temperature. Additional insulation will be replaced on a second servicing mission in the year 2000, during which Grunsfeld will spacewalk again.

Other tasks scheduled for the second servicing mission: installing the Advanced Camera for Surveys, which will be 10 times more powerful than the present Faint Object Camera, and fitting the telescope with new solar arrays and a new cooling system.

The telescope is named for Edwin Hubble, who showed that galaxies beyond our own existed in the universe and that the universe is expanding. These findings form the cornerstone of the big bang theory of the universe’s origin and opened the field of cosmology. Hubble received his S.B. in 1910 and his Ph.D. in astronomy in 1917 from Chicago.

Grunsfeld, who was born in Chicago in 1958––five years after Hubble died––received his S.M. in 1984 and his Ph.D. in physics in 1988 from Chicago. His doctoral thesis was based on data collected by Chicago’s cosmic ray detector, which flew as part of the Spacelab 2 payload on the space shuttle Challenger in 1985. In his thesis, Grunsfeld presented the first detailed measurements of the composition of cosmic rays at TeV energies.

“His thesis is certainly still the best work around in this area and hasn’t been surpassed since,” said Dietrich Müller, Professor in Physics, who developed the experiment along with Peter Meyer, Professor Emeritus in Physics. “It provides perhaps some of the best support for the present ideas of cosmic-ray acceleration in supernova shock waves.”

Grunsfeld has logged 26 days in space on two previous missions. His duties as a mission specialist aboard the shuttle Endeavour in March 1995 included helping to operate the ultraviolet telescopes of the Astro observatory, which provided astronomers a view of the universe impossible to obtain from the ground.

He also flew aboard the shuttle Atlantis in January 1997. It was the fifth mission to dock with Russia’s space station, Mir, and the second to exchange U.S. astronauts. In five days of docked operations, the crew transferred more than three tons of food, water, equipment and experiment samples between the two spacecraft.