Hans Mark was named Chancellor of the University of Texas system on May 30, 1984, after serving as Deputy Administrator of the National Aeronautics and Space Administration, and before that, as Secretary of the U.S. Air Force. A distinguished nuclear physicist and experienced faculty member and administrator, Dr. Mark now heads the fifth-ranking university system in the United States in enrollment, with more than 120,000 students. The UT system includes seven academic institutions, six health-oriented institutions, and the UT Institute of Texas' Culture. Chancellor Mark, whose academic and scientific career has spanned more than three decades, is a Fellow of the American Physical Society, the American Institute of Aeronautics and Astronautics, and the American Association for Advancement of Science. His list of significant scientific contributions reads like the syllabus for a space age course in modern science. Chancellor Mark played a pioneering role in the study of X-rays from stars, and did early work with what were later identified as black holes, among many other scientific accomplishments. Additionally, he is author or co-author of more than a hundred scholarly articles in his field.