The Cold Equations (The Twilight Zone)

On the frontier, any frontier, there can be little margin for error. Just as the first covered wagons making their way across the American desert had a finite supply of food and water, so too on this even vaster frontier are there laws that must be strictly observed. Thomas Barton has been piloting Emergency Dispatch Ships for five years. He has never been faced with this particular law of the frontier, until now. Thomas Barton is about to discover firsthand that there are limits, even here in the boundless reaches of the Twilight Zone.

Thomas Barton is an astronaut who must deliver a vital cargo of vaccine to a plague-stricken colony world. However, a young girl named Marilyn has stowed away on his vessel with hopes of reuniting with her brother Gerry at the colony. Now the entire mission is in jeopardy as her presence on board was not calculated into the flight plan, which goes strictly "by the numbers" and there will be no way for the pilot to compensate for her added weight. They also discover that there are no other ships which can pick her up prior to arrival at their destination.

While she is distraught that she will never see Gerry again, and because their ship is on a crash course, they attempt to compensate by jettisoning all possible extra weight. They discover, however, that the extra weight jettisoned is only half of what they need to make it to the colony planet.

Barton suggests that the girl try to contact her brother so they could at least talk before the impending doom. She finally contacts him in time, but only to talk about how they cannot meet in person. Barton considers sacrificing himself so the girl can survive, but finds this is impossible since she would not be able to pilot the ship herself. Resigned to her fate, Marilyn enters the airlock and allows herself to be jettisoned into space, leaving Barton to grieve in silence.

In the darkness, Thomas Barton hurtles toward his destination with the realization that there is room for emotion on the wilder frontiers of the universe. Emotion and memory of a girl who had not known that sometimes it takes a human life to balance the cold equation in the black geometry...of the Twilight Zone.

The original short story has had a number of other adaptations, beginning with an episode of the radio anthology series X Minus One in 1955.

• "The Cold Equations" at IMDb
• "The Cold Equations" at TV.com