Two years ago yesterday, a Harvard-educated astrophysicist addressed 50 students at the Science Center on the progress of the space shuttle program and the future of space exploration Today, he is orbiting the earth aboard the space shuttle Discovery.

Jeffery A. Hoffman, the only Harvard alumnus in the National Aeronautics and Space Administration's (NASA) 100-person astronaut corps, received his Ph.D in philosophy and astrophysics from the University in 1971.

Delays

Discovery took off at 8:59 a.m. yesterday, after five postponents and a 55-minute delay that force the countdown at nine minutes to lift-off.

The flight has been the focus of heightened attention because one of Hoffman's fellow crew members is Sen. Jake Garn (R-Utah), who is aboard as a congressional observer.

As chairman of an appropriations subcommittee that oversees NASA spending, Garn has long lobbied for a chance to fly on the shuttle.

36 Experiments

During their five-day flight, the crew of seven will deploy two commercial communications satellites, study space motion sickness and the effects of weightlessness on the cardiovascular system, and conduct 36 experiments that may lead to the development of new life-saving drugs.

Hoffman, a mission specialist, will operate an experiment to test special photographic equipment that will be used to photograph Haley's Comet from the shuttle next year, said Tina M. Griego, a NASA spokesman.

The Harvard astrophysicist will also participate in several experiments studying motion in the weightlessness of space, Griego said.

Hoffman graduated summa cum laude in astronoms from Amherst College in 1966 and spent the next three years at Harvard doing gammaray research. After receiving his Ph.D, Hoffman won several fellowships and studied in England for three years. In 1975, he was invited to work at the Massachusetts Institute of Technology's Center for Space Research.

After responding to a NASA recruiting posser, Hoffman was selected in 1978 as one of 35 mission specialists and pilots chosen from a field of 8079 applicants. Since then, he has trained and tested while awaiting his chance to fly on the shuttle.

The last Harvard degree holder in space was Harrison J. Schmidt, who earned a Harvard Ph.D in geology in 1961 and walked on the moon in December 1972 as a member of the Apollo 17 crew. After leaving NASA, Schmidt served one term as a U.S. Senator from New Mexico.

Hoffman, who was traveling 17,400 m.p.h. at an altitude of 281 miles yesterday, could not be reached for comment.