Boston — Bonnie Dunbar's childhood memories include nights of sleeping out on haystacks at the family farm, looking up at the stars, and thinking about being ''out there.''
''I didn't define it as wanting to be an astronaut, but I do remember at one point that I wanted to be a jet pilot,'' she recalls. ''I used to watch the television stations sign off at night with a picture of a jet going through the clouds, and I guess I was sort of naive about it - I didn't realize that women weren't jet pilots.''
Today Miss Dunbar spends some 15 hours a month co-piloting a supersonic T-38 trainer jet that can reach speeds of more than 800 m.p.h.. She also puts in a lot of time somersaulting inside an Air Force KC-135 to test the simulated microgravity of space as the plane roller-coasters through the sky.
Regular flight conditioning and airborne experiments are part of her training as a US astronaut. But like all of today's new breed of ''mission specialist'' astronauts, Miss Dunbar spends even more time in the classroom, studying aerodynamics, orbital mechanics, star identification, geology, and astrophysics. ''It's not all glory and fun,'' she says. ''There's a lot of work.''
Former senior research engineer at Rockwell International Space Division, and currently a doctoral candidate in biomedical engineering at the University of Houston, Miss Dunbar is a specialist in the production of the ceramic tiles that make today's space shuttle possible. Her conversation often turns to thermal protection systems, materials processing, and the kinds of satellite payloads that the Columbia space shuttle is scheduled to carry for the next few years.
But in among the technical references to dissipating velocity and synthesizing gravity are plenty of reiterations of a down-home ''by golly'' and ''wow.'' A Nellie Forbush in NASA flight suit, Bonnie Dunbar has the kind of all-American enthusiasm for career and country that must make Uncle Sam beam with pride.
''The US space program has never been a money sink,'' she says. ''It has made the world a better place. . . . and I'd like to see America maintain its lead in space technology.''
At a time of budgetary cutbacks and widespread questioning of the mission of NASA, Miss Dunbar sees the space shuttle as the next inevitable step in the development of transportation.
''We have entered an economic market,'' she begins. ''We're launching 20 satellites a year, and communications satellites are becoming a big business. We're going to get them up one way or another, and we want to do it cheaply. That's why we designed the space shuttle.
''As we developed cars, railroads, and airplanes, we needed gas stations, railroad stations, and air terminals,'' she continues. ''What we need now is a space station. What we call the Space Operations Center would allow us to do some of the best earth observations of weather, crops, and oceans, as well as materials processing and service repair of vehicles. It's going to happen . . . and it's certainly not going to help us economically to ask either the Japanese or the Europeans to launch our satellites for us.''
Although Miss Dunbar says that space no longer is the new frontier it was in the days of astronaut Alan Shepard, it's hard to listen to her talk about building furnaces that can be put into space to manufacture new alloys and crystals without catching some of her fervor. The same spirit lights up her smile when she talks about her own pioneering family.
''My parents are just phenomenal,'' she says. ''The farm I grew up on in eastern Washington had been barren land until 1948, when my mom and dad homesteaded there. They built a wood-frame tent that my mother lived in most of the time while my dad was doing wheat farming in northern Oregon. . . . There are still tree houses there that I built.
''I was part of the 1949 baby boom that came along at the time that the first sputnik was launched,'' she continues. ''I was the oldest of four kids, and we were very isolated from the nearest town, so I grew up as a bookworm and lived in a very imaginary world. I read a lot of science fiction and a lot of the old classics, too.''
Her parents, she says, told her she could do anything she wanted to do. ''My folks never steered me, but they also maintained that the only limitations you have are in your mind,'' she explains. ''We didn't have any college graduates in our family, and because I was the oldest, my mother almost made me swear I wouldn't get married until I had a college degree. She thought that was important.''A good student in both science and literature, Miss Dunbar was encouraged by a high school physics teacher to major in engineering in college and to continue reading as a pasttime. ''I considered MIT, but it was too expensive, and I also thought about going to Cal Tech - until they sent me a very nice letter telling me they didn't have any coeducational dormitories, which was another way of saying that they weren't academically coeducational.''Her decision to enroll at the University of Washington was an auspicious one. The school had been commissioned to help develop a thermal protection system for the space shuttle, and Miss Dunbar participated in the earliest research on the ceramic tiles that would be used to protect Columbia from the temperature extremes of space and earth re-entry. Still, she kept her interest in becoming an astronaut fairly quiet. ''When you go to school and pick a major, you don't say, 'I'm going to be an astronaut.' The only person I told at that time was the head of my department because I knew he wouldn't consider me absolutely bonkers.''After postgraduate work at the University of Illinois, and exchange work at England's Harwell Laboratories, Miss Dunbar went to work for Rockwell International, helping to set up production facilities for the space-shuttle tiles in California. She also developed some personal contacts at NASA, so she would know if and when the space agency was going to hire new astronauts, and if women were going to be among them.In 1978 she applied for the first NASA astronaut ''class'' accepting women. Although she wasn't selected for that program, she made it through the ''finals'' with a determination to try again. ''In looking over the resumes of those who'd been accepted, I realized that they had a lot of interests and worked in a number of different disciplines ,'' Miss Dunbar recalls. ''I could see that I needed to enlarge my background and improve myself. I was 29 by then, and was at the point where I was feeling, 'I don't want to be known as the tile expert all my life.'''When I'd been in Houston for interviews for the astronaut program, I'd been offered several jobs at the Johnson Space Center, and I decided there were some interesting possibilities in flight operations there. So I went from being a senior research engineer, working in a lab with materials, to being a systems engineer, working in an office with people.''Two years later, when she applied for the astronaut class of 1980, she was accepted. ''I just moved my office from one side of the building to another,'' she laughs.Bonnie Dunbar now is one of eight women in the 80-member astronaut corps. About half of the corps are pilot astronauts, all men , with military background in high-performance jet flying. The other half, like Miss Dunbar, are mission specialists, with either masters' or doctors' degrees in science, medicine, or engineering.''For the '78 class, there were about 8,000 applicants for 35 slots,'' she says. ''I'm not certain about the number of women who applied, but it might have been 800 or 900. So we do get a lot of women who apply. ''The reason so few women are selected is that you have to have a science or engineering background. When I started my education, only 3 percent of the engineering students were women, and now the proportion is up to about 15 or 20 percent. So we're beginning to see some growth in those areas. But what I really respect NASA for is not making the requirements any different for women.''Although she doesn't think she'll be the first US woman astronaut in space, Miss Dunbar does hope to go up on the shuttle within four years. All the astronauts are cross-trained in a number different fields, she explains, adding, ''I'd like to be so good in everything that they'll send me up soon!''A former lecturer for Rockwell International, Miss Dunbar often finds herself assigned by NASA to provide technical assistance to the news media covering the space shuttle program. Most recently, she was co-anchor with Dan Rather for the CBS coverage of the second Columbia flight.At a recent talk for New England high school students at Boston's Museum of Science, Miss Dunbar narrated a NASA film taken on board the second Columbia flight. ''If you put you heads on your left shoulders, you can see the view Dick Truly saw as he flew up the Florida coast, '' she advised at one point, adding a few seconds later, ''You don't know how funny you all look.''As the earth came back into view and the film ended, there was a momentary, perhaps awed hush in the audience. ''You can clap, it's okay,'' Bonnie Dunbar said. ''I thought it was pretty great, too.''