[vii] One of the most enjoyable parts of writing this book has been the opportunity to meet with some of the people involved in the HEAO program and to talk with them about their participation in HEAO. It gives me pleasure to acknowledge discussions with Gerry Austin, Elihu A. Boldt, Stuart Bowyer, Hale Bradt, E.T. Byram, Claude Canizares, George Clark, Talbot Chubb, Roger Doxsey, Robert Farnsworth, Herbert Friedman, Riccardo Giacconi, Paul Gorenstein, Art Gneiser, Herbert Gursky, Richard E. Halpern, F.R. Harnden, Jr., J. Patrick Henry, Stephen Holt, Martin H. Israel, Allan S. Jacobson, Ray Jorgensen, Lydie Koch-Miramond, Walter H.G. Lewin, James Matteson, Frank B. McDonald, Steve Murray, Marshall Novick, Albert G. Opp, Tom Parnell, B. Peters, I. Rasmussen, Tom Recio, Gunther Riegler, Ethan Schreier, Dan Schwartz, Fred Seward, Fred A. Speer, Harvey Tananbaum, and Kent Wood. Carroll C. Dailey and Wendell Johnson made helpful comments on the manuscript, as did William W. Pomeroy, who also provided much appreciated advice and support. I also wish to thank all the members of the HEAO team, many of whose contributions to the project were not mentioned specifically; nevertheless, they were vital to the success of the project. Finally, I wish to thank my wife, Karen. Her support, encouragement, and advice throughout the course of this work have been invaluable.