Guest Stars Derek Ware as Unit Sergeant Robert Robertson as Collinson Juan Moreno as Dobson Ronald Allen as Ralph Cornish Joanna Ross as Control Room Assistant Ric Felgate as Van Lyden Carl Conway as Control Room Assistant James Haswell as Corporal Champion Tony Harwood as Flynn Michael Wisher as John Wakefield John Lord as Masters Cheryl Molineaux as Miss Rutherford William Dysart as Reegan Robert Cawdron as Taltalian Roy Scammell as Technician Max Faulkner as Unit Soldier James Clayton as Private Parker Bernard Martin as Control Room Assistant Geoffrey Beevers as Private Johnson Ric Felgate as Astronaut Neville Simons as Michaels Neville Simons as Astronaut Steve Peters as Lefee Steve Peters as Astronaut Peter Noel Cook as Alien Space Captain Derek Ware as Astronaut Gordon Sterne as Heldorf Dallas Cavell as Quinlan Ray Armstrong as Grey Peter Halliday as Alien Voices Cyril Shaps as Lennox John Abineri as General Carrington
