James Franciscus

as Brent

as Lt. Mueller

as Carlo Giordani

as William Tyre

as Professor Hammond (archive footage)

as Tuck Kirby

as Pfc. Charles Harris

as Clayton Stone

as Peter Benton

as Conrad Morgan

as Self

as Bob Spangler

as Paul Diller

as Jonathan Livingston Seagull (voice)

Role: Story

as Tom Nelson

Role: Producer

as Jimbo

as Moke Blue

as President James Cassidy

as Charles Burnett

as Moses Brody

as Lt. Comdr. Jeffords, R.N.V.R.

as Maj. Hoffman

Role: Producer

as Stan Fisher

Role: Producer

as Steve Fulton

as Victor Khudenko

as Daniel Corban

as Clay Howard

as Nasa Archive Storyteller (archive footage from 'Seeds of Discovery', 1970)

as Lucky

as Brass

as Jimmy Halloran

as Youngblood Hawke

as Mike Longstreet

as Pvt. James B. Sorenson

as Self

as Eddie Baxter

as Paul Dover

as Johnny Doyle

as John Mason

as Dr. Matthew Tregaskis

as Mark Powers

as Bill Taylor

as Quinn Jackson

as John Fitzgerald Kennedy

as Chaplain Andrew Jensen

as Rick Leyton

as Mike Longstreet

as Tom Doane

as Tom Grover

as Self

as 2nd Lt. H. Kalasch

as John Novak

as Louis Coleman

as Russ Andrews

as Rush

as Sammy Stone

as Harry Scott

as Gil Davenport

as Dr. Lawrence Maddox

as Benjamin Elliot

as Dick Carriage

as Self

as John Mason