Tom Tryon as Capt. Richmond Talbot

Brian Keith as Maj. Gen. John M. Vanneman

Edmond O'Brien as McClosky aka 'Mac'

Dany Saval as Lyrae

Bob Sweeney as Sen. Henry McGuire

Tommy Kirk as Walter Talbot

Kent Smith as Secretary of the Air Force

Sarah Selby as Mrs. Talbot

Nancy Kulp as Nutritionist Officer

Bert Remsen as Brennan

Harp McGuire as Federal Security Driver

Simon Scott as Medical Officer

Robert Brubaker as Space Flight Technician (uncredited)

Walt Davis as Air Force Officer (uncredited)

Douglas Evans as Colonel (uncredited)

Sally Field as Beatnik Girl in Lineup (uncredited)

Michael Garrett as Control Board Technician (uncredited)

Bob Hastings as Motorist (uncredited)

Jonathan Hole as Hotel Clerk (uncredited)

John Holland as Joe McCord (uncredited)

William Hudson as Space Flight Technician (uncredited)

Kenner G. Kemp as Conventioneer in Hotel Lobby (uncredited)

Nancy Kulp as Space Flight Nutritionist (uncredited)

Muriel Landers as Fat Lady (uncredited)

Harp McGuire as Federal Security Driver (uncredited)

Karen Norris as Bridge Player (uncredited)

Nelson Olmsted as Police Officer Dennis (uncredited)

Jeffrey Sayre as Conventioneer in Hotel Lobby (uncredited)

Bert Stevens as Conventioneer in Hotel Lobby (uncredited)

Chet Stratton as Captain (uncredited)

Arthur Tovey as Conventioneer in Hotel Lobby (uncredited)

Guy Wilkerson as Conventioneer in Elevator (uncredited)

Jo Anne Worley as Beatnik Girl in Lineup (uncredited)

John Zaremba as Security Officer Conducting Lineup (uncredited)