For all its successes, it seems NASA is still learning with every flight. Pettit seemed to surprise his audience by telling them that the effort required to turn around the space shuttle after each flight, before it could be certified ready for another flight, was 300 man-years. Man-years are the number of hours a person works in a year. He estimated it required only a man-month, or roughly 160 hours, to prepare a commercial airliner for another flight. He wondered aloud if it just might be easier and cheaper to use expendable launch vehicles.
Space flight is tough.
Pettit spent the last few minutes of his talk answering questions from the audience, both young and old. He handled the obviously painful comparison of the exploding engine videos to the tragic Challenger Shuttle explosion by detailing the differences between the two. The Challenger explosion was due to malfunctioning O-rings, he noted. The engine explosions shown in his video were typically due to turbine failures. It was here, more than anywhere else, that it became obvious Pettit was a man who saw few limits in what science and scientists can achieve.