One small step for Jeff Hoffman, one large step for NASA.

After more than 150 parachute jumps, a hike up New Hampshire's Mt. Washington on skis, three previous space flights and other experiences in free-fall, Dr. Jeffrey A. Hoffman, NASA astronaut and Harvard astrophysics Ph.D. (1971), was ready last week when he stepped into space to repair one of the world's most expensive telescopes.

The New York native was one of four mission specialists aboard Space Shuttle Endeavor's recent Hubble telescope rescue mission, which included a NASA record five "extra-vehicular activities," or spacewalks.

Hoffman's task was to participate in spacewalks to conduct servicing and repair activities on the Hubble. The telescope was launched in 1990 with a misshapen mirror, due to a manufacturing error, which prevented it from discerning the more remote objects in the cosmos.

Hoffman and four other crewmates embarked upon several spacewalks last week and successfully installed a set of corrective mirrors and a new camera with corrective optics, replaced two rate-sensing gyroscopes and two magnetic sensing systems used in orienting the telescope and carried out a host of other necessary repairs, according to a NASA spokesperson.

According to Giovanni G. Fazio, lecturer in astronomy and one of Hoffman's mentors while he was at Harvard, Hoffman exuded confidence prior to the mission.

"A lot of us were very worried whether this repair could come off," says Fazio. "But Jeff was always very positive about it."

Hoffman graduated summa cum laude from Amherst College in 1966, received his doctorate in astrophysics from Harvard in 1971 and obtained a masters degree in materials science from Rice University in 1988. His doctoral work at Harvard focused on the design, construction, testing and flight of a balloon-borne, low-energy, gamma ray telescope.

But according to Hoffman's fellow graduate students, the future astronaut was never without some idea for an adventure in travel.

"What was anybody doing in the late 60s?" asks Professor of Astronomy Jonathan E. Grindlay, a Ph.D. candidate with Hoffman. "We did lots of crazy things, like heading for the mountains in New Hampshire and skiing in Colorado."

And despite his adventurous nature, says Fazio, Hoffman's friends and colleagues expected him to keep a bit closer to terra firma.

"We never expected him to become an astronaut," Fazio says. "He never discussed it."

Grindlay, however, disagrees. "In our grad student days, at the time of the Apollo moon landing, Jeff was pretty excited about [the idea of becoming an astronaut]," he says. "I don't think he thought it was a realistic opportunity at that time, but we were both speculating about how exciting it would be to do astronomy from space."

And Walter H. G. Lewin, professor of physics at MIT and a personal friend of Hoffman's says that Hoffman's quest for a journey into space was not an easy one.

According to Lewin, who was invited by Harvard to sit on Hoffman's Ph.D. committee, Hoffman decided to apply for the NASA astronaut program even though his chance for admission was about 12 in several thousand.

Hoffman didn't make the first cut, but after Congress requested that NASA reevaluate the selection, he was accepted and granted the title of a full-fledged space cadet.

Many of Hoffman's teachers and colleagues say they are not surprised to hear of his "astronomical" achievements.

"He has the ability to work hard, follow directions, and find out why things don't go right when they should--all qualities an astronaut should have," says Henry F. Helmken, Professor of electrical engineering at Florida Atlantic University and Hoffman's thesis advisor at Harvard.

"He is a man who keeps his cool under almost all bizarre and difficult situations," says Lewin.

According to Lewin, during one of Hoffman's 150 parachute jumps, his parachute failed to open completely and he began to plummet in free-fall toward the ground.

"Most people in this situation, in panic, pull the energy backup string [causing the parachutes to entangle] and free-fall to earth, killing themselves," says Lewin.

But in mid-free-fall, Hoffman timed his speed of descent with an altmeter and a stopwatch. Within 10 seconds, he determined that his impact speed would be too high, took off his primary parachute, opened his backup, and landed safely.

"You can't wish for a better astronaut than Jeff because in space, he'd do exactly the right thing," says Lewin.

Ken C. Atchinson, a NASA spokesperson, agrees. "We're all delighted," he says "[Repairing the Hubble] has been one heck of a major challenge and we anticipated great difficulty. Jeff did a stupendous job just like the others."

The Endeavor mission was scheduled to return yesterday. Hoffman's future plans include giving a colloquium at Harvard about the mission, according to Fazio.

Hoffman could not be reached for comment last week--he was in space.