Who's missing?

Below is a list of an investigation team created in the aftermath of a famous disaster. You have tell me who is missing. You don't need to google this...

William P. Rogers, David C. Acheson, Eugene E. Covert, Richard P. Feynman, Robert B. Hotz, Donald J. Kutyna, Sally K. Ride, Robert W. Rummel, Joseph F. Sutter, Arthur B.C. Walker Jr, Albert D. Wheelon, Charles E. Yeager and Alton G. Keel Jr.