National Aeronautics and Space Administration

Glenn Research Center

Joe Prahl

The NASA Space Academy’s final speaker, Professor Joe Prahl, has spent most of his career as a professor in the Department of Mechanical and Aerospace Engineering at Case Western Reserve University. His research has focused on lubrication and tribology with the exception of three years from 1990 to 1993 where he trained as a NASA payload specialist for Shuttle flight.

Dr. Prahl’s presentation focused primarily on his astronaut training years. Specifically, he lectured on “Why We Go” (to space). This involved the dynamic and kinematic equations necessary for resolving the acceleration forces on an experiment orbiting the earth in the Space Shuttle. Upon first look, an orbiting mass in a circular orbit around the earth should experience zero gravitational forces, since its centrifugal acceleration matches its gravitational forces. However, when analyzing the forces of an object which lies outside of the object’s center of mass, some gravity forces are noted.

With this in mind, he also discussed the failure to install the primary experiment (a study on zero gravity crystal growth) aboard STS-50 at the orbiter’s center of gravity. Mistakes in manufacturing the size of experimental apparatus components forced the equipment to be mounted off center. The crystal growth experiment, which required extremely low gravity, failed.

The remainder of the talk was dedicated to his experience in the astronaut corps. He was recommended as a payload specialist by his friend and principle investigator of the STS-50’s main flight experiment. After three years of training, he was the backup to payload specialist Eugene Trinh, but did not get to fly aboard the Space Shuttle.

Dr. Joe Prahl was an excellent ending to the NASA Space Academy lecture series, as he had a positive and encouraging outlook on NASA’s future, despite the wake of recent budget cuts and general lack of public interest.