VICTOR G. SZEBEHELY, DEng, PhD(1921-1997), was Professor and former chairman of the Aerospace Engineering and Engineering Mechanics Department of the University of Texas at Austin. He served as a consultant to the U.S. Air Force Space Command. HANS MARK, PhD, is Professor in the Aerospace Engineering and Engineering Mechanics Department of the University of Texas at Austin. His other books include The Space Station: A Personal Journey. He serves as a consultant to NASA.