Retired NASA astronaut and veteran of three space flights. A member of the United States Astronaut Hall of Fame, he won numerous honors, including several NASA Space Flight Medals and a NASA Exceptional Service Medal.
He earned a PhD in astronomy from George Washington University.
He logged ten hours of EVA (extra-vehicular activity) time.
His marriage to Susie Nelson produced two children: Marti and Aimee.
He flew on the first mission after the Challenger explosion that killed Judith Resnik.