Not many people have orbited the planet more than 750 times, and very few of them have been women. Bonnie Dunbar (see picture at left), who visited Cambridge earlier this year to talk about her inspiring career, is a member of an elite team of women that has participated in the space race over the last 35 years. From graduate student to her current role as an assistant director of the NASA Johnson Space Center, her career in science and engineering has always been closely linked with the advances and applications of space technology.

Dunbar?s space career was inspired in October 1957. She followed the events around the launch of the first humanmade satellite, Sputnik 1, from her home in a small farming community in Washington State. It was a hard-working community, where her parents treated all four of their children the same. It was little different at school. With only 22 children in a class, Dunbar recalls, every one was important. Having boy?s teams and girl?s was not an option; the choice was to have a co-ed team or nothing at all.

Her parents brought her up to live her dreams. So when Dunbar decided that she wanted to be part of the space race, her only question was ?how do I get involved?? The answer set her off down the ?math path? at high school, where she specialised in physics, chemistry, and maths. Graduating in 1967 she won a place to study engineering at the University of Washington, Seattle.

The freshman class in general engineering was very competitive. As one of only six women in a massively oversubscribed class, the pressure was on. Half of the 2000 students would have to be flunked at the end of the first year. But Dunbar was successful, and now she had to decide which branch of engineering to specialise in.

Driven by her passion for space exploration, the choice seemed obvious: astronautical or aeronautical engineering. But fate played its hand. In the same year that Dunbar entered university, NASA decided to build a reusable space vehicle. Dr James Mueller, a ceramics engineer and strong influence on Dunbar, won a NASA research grant to design the ceramic heat shield tiles that would protect the Space Shuttle during re-entry into Earth?s atmosphere. Seeing her first chance to contribute to the space race, Dunbar joined Mueller?s group as an undergraduate researcher and began working on the design of the revolutionary thermal protection system.

After graduating, Dunbar spent 2 years at Boeing in Seattle working as a systems analyst before returning to the University of Washington to complete a master's degree in materials science. She was then invited to join the UK?s Harwell labs, returning to the United States to join Rockwell International?s Space Division in 1976, where the Space Shuttle?s thermal protection system was once again the focus of her research.

But Dunbar?s career hasn?t been restricted to a single material. For her Ph.D., Dunbar turned her attention to the effects of microgravity on bone strength, graduating in 1983 from the University of Houston after adding a biological science to her list of qualifications.

In 1977, NASA began recruiting ?highly qualified individuals? to become the first group of astronauts to fly the space shuttle. Dunbar?s successes in her research career made her ideally qualified to fill out the application form for the chance to become an astronaut. The selection procedure took over a year, culminating in a week of interviews and medical tests before Dunbar knew that she was one of 19 successful candidates to win a place on the astronaut candidate training programme at NASA?s Johnson Space Center.

The programme involved a wide range of classes, including training in survival techniques as well as experiencing extreme atmospheric pressures and microgravity simulations in a KC-135 jet aircraft. After a year of training, Dunbar achieved her goal, and in August 1981 was appointed as a NASA astronaut.

Since then she has participated in a total of five space flights, spending 50 days in space and travelling millions of miles. During her last Space Shuttle flight in 1998, she served as payload commander, overseeing 23 science and technology experiments, as well as supervising the delivery of 4000 kg of equipment, hardware, and water destined for the Russian MIR space station.

Between 9 and 18 months of training lie behind every Space Shuttle mission. All the experimental procedures are rehearsed on the ground, and Space Shuttle crews even go to the extent of visiting research groups in their labs while preparing to run their experiments in space. But once in orbit, things don?t always go as planned. Sometimes the crew has to make unexpected decisions and fix broken equipment. As a payload commander, Dunbar felt an incredible sense of responsibility to the scientists that she represented in space, and she pays tribute to her colleagues on each Shuttle mission, remembering that she always worked with "great teams [that she] never had to manage too hard."

But Dunbar does have some concerns about the future role of women in space. The selection standard for astronaut height is meant to go from "5th percentile Asian women up to the 95th percentile of Caucasian men," but NASA?s recent decision to halt development of a smaller space suit could have a significant effect on the number of women going into space. Of the 34 female astronauts currently working in the United States, there is no space suit for 16 of them, and the available medium-sized suit is only "a marginal fit" for another 15. This is having a serious impact on the number of women working on the International Space Station (ISS), where every astronaut must have a space suit available. And Dunbar points out that this decision doesn?t just affect women; it will also have a significant impact on the other nationalities that are committed to the ISS, with 90% of Japanese men falling below the height requirements to wear the medium-sized space suit.

After 20 years at the Johnson Space Center, Dunbar is currently serving as the assistant director for university research. She is responsible for overseeing educational programmes and building collaborations with universities. Dunbar has been successful in everything she has done, but she also remembers that she had to overcome difficult times too. Her advice to wanna-be astronauts: "engage your passions. That will take you through the rough patches."