NASA / GETTY IMAGES
	Laurel Clark participates in a mission training session last year at Johnson Space Center.

Fascinated by the environment, ecosystems and the animal kingdom, Clark immersed herself in zoology at the University of Wisconsin, then moved toward a career in medicine, thinking she would do her life's work on her home planet.

"I can't think of anything specific growing up that pointed me toward NASA at all," said Clark, married with one child. "I was interested in the moon landings just about the same as everyone else of my generation. But I never really thought about being an astronaut or working in space myself."

Clark, 41, graduated from the University of Wisconsin with a degree in zoology in 1983 and received a doctorate in medicine from the school in 1987. An Iowa native, she considered Racine, Wis., her true hometown.

She trained with a Navy medical-diving unit while in medical school, then did a postgraduate year in pediatrics at Bethesda Naval Hospital in Maryland. From there, she completed her training in Connecticut and Panama City, Fla., becoming certified to work in submarines and as a medical diver.

From those close quarters, the idea of cramming into the space shuttle wasn't much of a leap.

"It was really just sort of a natural progression," Clark said. "When I learned about NASA and what astronauts do, and the type of things that they are expected to do, I thought about the things I had done so far and became more interested in that as a career."

Clark also trained as a flight surgeon, and served in that capacity for the Naval Flight Officer advanced-training squadron in Pensacola, Fla. She rose to the rank of commander, earning three commendation medals and the National Defense Medal, before being accepted by NASA for astronaut training in 1996. She was qualified for a flight assignment, as a mission specialist, two years later.

During her maiden flight aboard the Columbia, Clark worked closely with the assorted experiments on board. That included using the astronauts themselves as test subjects, looking for ways the body responds to life in orbit.

"As a physician, the life-science research that we're doing is extremely exciting," Clark said.

— Michael Cabbage, The Orlando Sentinel