The moon swings through a solar system containing the Earthlike world of Ariel, but just as the first expedition is launched to visit the planet, an unmanned probe meets Alan Carter’s Eagle halfway there. Fearing it may be a bomb, Koenig orders the mission aborted and has the Eagle brought back to Moonbase Alpha by remote control. The device doesn’t explode, but instead begins spewing out gas. More probes, all identical, touch down on the lunar surface and follow suit, and Koenig fears an invasion. Bergman discovers that the massive amounts of gas delivered by the probes are breathable air, giving the moon a summery, Earthlike atmosphere. If the moon gets close enough to Ariel’s sun to take up an orbit, this new paradise will permanently rid the Alphans of their need to colonize another world. But if the moon slips through Ariel’s system, the atmosphere will dissipate again…and if that happens while members of the crew are still outside exploring their newly terraformed home, it’ll mean certain death for them.
written by Christopher Penfold
directed by Charles Crichton
music by Barry Gray
additional music by Vic Elms
Guest Cast: Prentis Hancock (Paul Morrow), Clifton Jones (David Kano), Zienia Merton (Sandra Benes), Anton Phillips (Dr. Mathias), Nick Tate (Alan Carter)
LogBook entry by Earl Green