A graduate of the University of Washington, where she earned a Master of Science degree in ceramics engineering, Dunbar became a senior research engineer in Rockwell International's Space Division, where she designed the equipment and manufacturing processes used to fabricate the ceramic tiles used in the Space Shuttle thermal protection system.

Dunbar left NASA to become the president and chief executive officer of the Museum of Flight in Seattle, where she was involved in science, technology, engineering, and mathematics (STEM) education for high school students.

[1] She became fascinated with space, reading science fiction novels by H. G. Wells and Jules Verne, and following the real-life exploits of the Mercury Seven.

[1] She attended Sunnyside High School, where she took physics and chemistry and math algebra, trigonometry, analysis and precalculus classes.

She was interested in the Romantic poets like Lord Byron, Percy Shelley and John Keats, but she still wanted to build spacecraft, so her physics teacher advised her to study engineering.

[2] As a freshman, she aspired to join the university's Air Force Reserve Officer Training Corps (AFROTC) unit, but it did not accept women then.

[3] Engineering jobs were hard to find in 1971, so Dunbar accepted a position as an office manager at a Seattle linen-supply company.

Two months later, she secured a position in the computer services division at Boeing through her experience in writing programs in Fortran IV.

After a year and a half, she got a call from Mueller, who informed her that he had secured a grant from NASA, and asked if she would be interested in graduate school.

Before she left for England, she had already accepted a position in Downey, California, as a senior research engineer with Rockwell International's Space Division starting in October 1976.

[4] Her responsibilities involved developing the equipment and processes required to fabricate the Space Shuttle thermal protection system tiles that she had worked on as an undergraduate.

She was selected as one of 200 finalists, and was asked to report to the Johnson Space Center (JSC) in Houston, Texas, for a week of interviews and evaluations, commencing on October 17, 1977.

Her research project involved testing rats with hind leg suspension as a means of simulating the effects of a microgravity environment.

She would dissect their femurs to study the bone, and measure their strength in the Instron machines in the Structures and Mechanics Laboratory (Building 13).

[2][4] Her thesis on the "Effects of antiorthostatic kinesia on Sprague Dawley rat femur fracture toughness and concomitant alterations in metabolic activity" was accepted and she was awarded her doctorate in 1983.

She was a member of the Flight Crew Equipment Control Board, and as such was involved in the remote manipulator system (RMS) development.

She later became the chief of the Mission Development Branch, and was the Astronaut Office interface for "secondary" payloads, and the lead for the Science Support Group.

Dunbar reported this to George Abbey, who drafted a memo to the DFVLR stating that all equipment for the mission had to accommodate a range of sizes.

[8] Challenger landed at Edwards Air Force Base in California on November 6, after 7 days, 44 minutes and 51 seconds, during which it had traveled 2.5 million miles and orbited the Earth 111 times.

It had been launched by the STS-41-C mission on April 7, 1984, and by January 1990 its orbit had decayed to about 175 nautical miles (324 km) and it was only a month or so away from re-entering the atmosphere and burning up.

Other experiments investigated protein crystal growth, echocardiography, latitude/longitude locating, mesoscale convective system lightning and circadian rhythms.

The crew themselves were test subjects for investigations of the benefits of in-flight aerobic exercise and human adaptation to extended duration missions.

It was realized that leaving materials science to the Europeans and Japanese meant that NASA had no research facilities in development of the kind that were envisaged for the Space Station Freedom.

Over the next thirteen days, the payload crew of four performed a series of experiments related to human physiology and the growth of various crystals in microgravity.

No American astronaut had served as a backup since the early days of the Space Shuttle program, and none had flown or even trained for a long-duration mission since Skylab, almost twenty years before.

[25][28] On February 4, 1994, NASA announced that Thagard and Dunbar had been selected for the prime an backup crews for a three-month flight on Mir in 1995.

[29] In February 1994, Dunbar traveled to Star City, Russia, where she spent thirteen months in training to be a back-up Mir crew member.

[25] This included survival training for the contingency of a landing in the Arctic region of northern Russia, which Dunbar enjoyed, as it reminded her of home.

As it happened all seven Shuttle-Mir astronauts ultimately returned to Earth on Space Shuttle missions, but an emergency evacuation in a Soyuz spacecraft was always a possibility.

[8] To obtain this credential she took a series of final oral examinations for each system, in which members of the training department fired questions at her in Russian.