As the space shuttle Columbia touched down on a California runway yesterday morning, the men who run things at Mission Control in Houston took off their headphones and applauded the successful conclusion of one more voyage into space But, for at least one of these men, the cheering signaled far more than just relief. With the end of the Columbia's fifth space flight, astronaut Jeffrey A Hoffman moved one step closer to his long-awaited first day in space.

The 38-year-old Hoffman, who received a Ph.D. in Astrophysics from Harvard in 1971, is believed to be the only one of the 79 U.S. astronauts with a Harvard background. Selected in 1978 as a mission specialist for the shuttle program. Hoffman belongs to a new breed of space scientist--a generation of astronauts quite distinct from the toughened test pilots who grabbed the world's attention during the pioneering Mercury. Gemini and Apollo programs

Hoffman and the other 19 mission specialists selected with him in 1978 are scientists and engineers--not pilots--by training As such, they have been trained to take care of everything except actually flying the ship, which is left to shuttle pilots. And for Hoffman and his colleagues, the shuttle flight which touched down yesterday morning marked a special hurdle Astronauts Joseph Allen and William Lenoir--who launched the shuttle's cargo of two commercial satellites were the first two mission specialists ever to fly in space

Hoffman and his colleagues differ from their predecessors in another, perhaps even more important, way When the National Aeronautics and Space Administration (NASA) in 1978 announced the selection of the astronaut group that included Hoffman, a reporter asked the director of the Manned Space Flight Center in Houston to comment on his new charges Christopher C. Kraft Jr. said the new astronauts--the first picked by NASA in more than eight years--were "extremely highly qualified and motivated, because, unlike previous applicants, many have wanted to become as turnouts since they were 10 or 12 years old."

In Hoffman's case, Kraft was a few years off

"I was basically interested in space since I was six," Hoffman says. "Rockets were the neatest things around." He recalls having a avid interest in science fiction, and being fascinated by the stars when he visited the planetarium or peered through his father's telescope.

But because the early astronauts were of the test-pilot school and a little closer to American hero status then he ever dreamed of being, the Brooklyn-born Hoffman says he "didn't relate to the space program personally." The astronaut recalls that he never talked about his ambition, keeping it secret even from his parents "because it seemed sort of frivolous." Nevertheless, he adds, "I was dead serious about it."

In 1962, just as the space program was beginning to mature--and the same year that John H. Glenn Jr. became the first American to orbit the earth--Hoffman graduated from Scars dale High School. At Amherst College, Hoffman followed his scientific bent, majoring in Astronomy, and graduating first in his class,summa cum laude. Then, without skipping a beat, Hoffman arrived at Harvard to embark on three years of gamma ray research. This work took him as far away as Argentina, where he experimented with a balloon-borne gamma-ray observatory that he designed and built.

Giovanni G. Fazio, a lecturer on Astronomy who worked with Hoffman at Harvard, says that Hoffman was "very energetic" in his desire to find sources of certain cosmic rays The balloon experiments, he adds, were designed to lift instruments above those levels of the atmosphere that could interfere with the "search for radiation from celestial objects."

Following his Ph.D. Hoffman received a string of fellowships that began with more gamma ray research at the Harvard-Smithsonian Astrophysical Observatory, and eventually led to a three-year stint with a prestigious astronomical organization in England, where he met his wife, Barbara.

From his post in England, where he participated in a satellite project. Hoffman was invited in 1975 to work in MIT's Center for Space Research. As MIT scientist Walter Lewin recalls. Hoffman's work there with two astronomical satellites helped lay the groundwork for an important new theory on the source of X- rays in space

"Those were incredibly exciting years." Hoffman says of his time at MIT, where he actually helped control and monitor one of the satellites be worked on.

"Jeffrey is one of the most conscientious people," Lewin says of his former colleague adding that he is "happy, as a taxpayer, to know that people like him are working in the government."

For a while however. Hoffman never thought be would have a chance to work for the government --or at least for NASA. But in 1977, Hoffman saw a poster in an MIT lab announcing NASA's recruiting drive.

"Given an opportunity to apply there was no way i could say no, Hoffman says. But the odds were not encouraging: out of 8079 applicants for pilot and mission specialist openings, NASA selected 20 mission specialists and 15 pilots. After first making the finalists group of 208, Hoffman was flown to Houston for a week of interviews and medical exams. Shortly thereafter, many of Hoffman's relatives, friends and colleagues started getting calls from the FBI, inquiring about all the personal details that NASA needed to know before putting someone in the back seat of their billion-dollar space plane.

Taking the inquires--which friends were quick to tell him about--as a sign that he was still in the running. Hoffman held his breath until the call finally came. With the phone call came the move to Houston.

Difficult as the application process was, it was easy compared with NASA's basic training Hoffman says that much of the year he spent as an astronaut candidate "was like going back to school," with courses ranging from aeronautics to astronauts

One aspect of the training which the astronauts both enjoy and dread is floating aboard a specially padded plane that is flown in parabolic curves to simulate weightlessness. The astronauts have nicknamed the plane the "Vomit Comet," evidently for good reason.

"It's as much fun as it looks, but you can really get sick as hell." Hoffman says about the "physiological familiarity" tests conducted aboard the plane.

Life as an astronaut, however, is not all fun and games. "Basically, what you do around here is on-the-job training." Hoffman says, explaining that most astronauts spend their time helping to develop new equipment or computer software for the shuttle, using simulations or working with contractors and scientists directly. The end goal is attaining a thorough understanding of how the space shuttle operates Because astronauts may spend as much as a year dealing with one particular system, each man tends to develop an area or two of expertise Hoffman has written a training manual on the Orbital Maneuvering System, which is one component of a complex guidance system that helps to control and steer the shuttle in orbit

Although Hoffman is not yet scheduled on a shuttle flight, he hopes to be selected soon for a mission sometime in 1984 In the meantime, Hoffman continues training and testing while performing more specific tasks for each shuttle flight.

During the fifth flight, Hoffman served as a member of the two man support crew, a plum job which put Hoffman as close to the job as he could be Over the past year, as Columbia's most recent veterans trained intensively for their mission chores. Hoffman helped to work out the flight procedures while assisting the crew with simulations and other training As a result of his close work with the four astronauts. Hoffman became "as good a person as anyone else to know what's going on," and stood ready in Mission Control over the course of the five-day flight in case controllers had any questions

"I feel a lot of me flying up there with them." Hoffman said in a telephone interview the night before last Thursday's march. He added that he had had dinner with the astronauts just prior to their departure for the Cape Canaveral. Fla,. launch site.

On the fourth flight, Hoffman served as a media representative for NASA, helping to explain the shuttle program on CBS and National Public Radio. Over the past few years, NASA has also sent Hoffman on speaking tours of public schools

While most of the training and the work is enjoyable, there is also "a lot of tedium, boredom, and frustration." Hoffman admits, saying that he often spends about three-quarters of a day in meetings. "We don't sit around in our spacesuits all the time," he quips.

"People ought to realize it is a job, but it is an incredibly exciting one--after all, we are preparing for space flight. When things get frustrating, you've got to sit back and look at the big picture again."

Waiting for a flight is easier today than it was before the shuttle program. When flights were few and astronauts trained several years for each flight, Hoffman explains, telling of astronauts selected in 1967 who have been waiting for 15 years to fly in space.

"Now, there are going to be plenty of flights for everyone," he adds, saying that the astronauts selected with him in 1978 are just starting to be selected for crews. Sally K. Ride, one of six women selected in 1978, will fly on the seventh mission next April, becoming the first American woman to go into space.

Invitably in the course of media coverage of this shuttle, the focus shifts to Tum Wolfe's The Right Stuff, a compelling description of the early astronauts, their legacy as true pioneers, men and men only--who scraped the edges of space in a variety of sleek rocket planes and flying contraption. Today, Hoffman notes, the astronaut corps is comprised of people of all backgrounds. His group includes the first three Blacks and an Oriental. Hoffman, himself is one of the first Jewish astronauts.

The one thing common to all the astronauts. Hoffman says, is the fact that they are all pushing towards the same end, and would like to stay alive in the process. "There's no right stuff, in the test pilot kind of way, but we all get an appreciation of what it's like to work with a very complicated vehicle in a basically unforgiving environment."

While Hoffman says he's not scared by the possibility of an accident his mother says that she "is naturally apprehensive and nervous about it," and especially anxious about the prospect of her son's first launch into the void of space

"Whether I could keep my eyes open watching that thing blast off, knowing that Jeff is inside of it. I don't really know," Elizabeth Hoffman adds, recalling that "he never seemed like a real daredevil type" and was "basically very quiet and scholarly" as a youngster

Although Hoffman's wife Barbara says she gets seasick very easily, she is not fearful of her husband's future travel plans

"Actually, this is probably one of the safest things that he has ever done." Mrs. Hoffman says, noting that her husband is an avid mountain climber and has climbed some of the more challenging slopes in Europe. He also enjoys sailing and windsurfing, and, during the winter months, cross-country and downhill skiing.

He also stays fit on a daily basis, bicycling the seven miles round trip between his home and the Space Flight Center.

Barbara Hoffman says her husband is not a workaholic and keeps his work week to about 40 hours, unless there's a flight. She adds that he divides his time very well between his work and family life--spending time with their two sons, ages three and seven.

Hoffman says it is hard to imagine being an astronaut forever, but that at the moment, he is in an ideal position: as an astronomer, he may one day be able to observe space from space, where the atmosphere-free environment provides the best possible view of the cosmos. Although there is no guarantee that he will have such an opportunity. Hoffman says at least that he "fully expects" to spend the rest of his life as a research scientist. Although he won't commit himself to the possibility of serving as an astronomer on some future space station. Barbara Hoffman says, "I know he would go." Asked if she would join him there, she adds, "I can't see myself wanting to do that."

Like his colleagues in the space business. Hoffman is firmly committed to the future: "The biggest challenge we have now is to learn how to fly [the shuttle], fly it well, and have it become routine," he says, adding that the opportunity to help meet that challenge is well worth the wait.

"I wouldn't trade it for anything." He says