Sci-fi is a genre built on pushing the limits of the imagination, but for all its originality, there is still an abundance of groan-worthy tropes. Aliens are invading … again. The computer is probably evil. And those ever-present pew-pew-pew sound effects? They should not exist.

Among sci-fi's most confounding motifs is what I'll call "the dead child back-story." Almost every astronaut seems to have one, from the protagonists of critically-acclaimed films like Arrival and Gravity, to the widely-panned Netflix release Cloverfield Paradox. The new Syfy series Nightflyers, which premieres Sunday at 10 p.m., is no different. It uses an unthinkable terrestrial occurence — the death of a child — as inroads into more astral phenomena.

Based on a 1980 novella by George R. R. Martin, Nightflyers is Syfy's expensive new bet on the Game of Thrones author. But anyone seeking dragons and knights is out of luck here; Nightflyers follows a colony ship into the outer reaches of space as its crew seeks to make first contact with a race of aliens thought to be the only chance at saving Earth from its own self-inflicted destruction. But then, conditions on board the ship begin to go fatally awry as its systems, Hal-like, turn against the crew.

Enter the dead child. Astrophysicist Karl D'Branin (Eoin Macken), the leader of the scientific team on the colony ship, has lost his young daughter Skye to a deadly disease on Earth. Skye is naturally a sort of Achilles' heel for Karl, and the manipulative psychic forces on board the ship use her image to haunt him. The metaphor is as obvious as it sounds: Karl is also haunted by his guilt associated with Skye's death, which manifests in the form of her lashing out at him for failing to save her. Based on Karl's own unraveling, we might even forgive his Earth-bound wife for undergoing therapy to have memories of Skye erased completely from her mind. (There is actually also a second dead child in Nightflyers, although I will leave that twist to viewers).

Skye's function in the story, like dead children in many other space dramas, is partially a matter of logistics. Sci-fi stories frequently would have us wonder how a parent could justify going on such a reckless mission into the unknown if they had a family back on Earth, and this is especially true for female characters. All too regularly it is mothers who have to be "released" from their children in order to be gutsy enough to go to space, Bustle points out. In Arrival, Dr. Louise Banks' (Amy Adams) dead child allows her to venture unencumbered into her rendezvous with potentially dangerous foreign lifeforms. And the worst offender of all is Gravity, in which astronaut Ryan Stone (Sandra Bullock) agrees to fix the Hubble telescope in part because her kid died in a freak accident during a game of tag.

Why is this plot line so common? It could be because science-fiction is a natural platform for exploring the theme of death. After all, in probing the far-reaches of science and space, one naturally collides with that greatest unknown of all. More specifically, children's deaths represent something that audiences — or at the very least, protagonists — cannot fully understand. Adults dying is a universal fact, but there is a Dostoevskian incomprehension around how innocent children can be taken. By butting up against this reality, the parents in even the most hard science-fiction features and shows are forced to confront the imaginatively impossible. For Nightflyers' Karl, turning over the facts of Skye's death is no less inconceivable than a time-bending race of aliens, or the possibilities of the consciousness of the ship he lives on.

There is also the physical aspect of space travel; in departing our home planet for the heavens, the out there metaphorically becomes the place where parents grapple with their Earth-bound losses. It is in the unknowable that we find answers for the unfathomable.

In the worst instances, though, the dead child trope is lazily used to explore these greater themes, or worse, as the emotional thrust in an otherwise conventional, or even boring, story. As George Lucas has acknowledged, "emotionally involving the audience is easy ... get a little kitten and have some guy wring its neck." In Arrival, the child is used as a literal plot twist. The child in Aliens was deemed so disposable to the plot that in trying to shorten the film for its theatrical release, the plot line was cut entirely. Even First Man, which is not science-fiction but rather a biopic about Neil Armstrong, uses the astronaut's daughter's death to give the narrative its contrived emotional arc.

The Nightflyers finale doesn't air until Dec. 13, so it is too soon to tell how Skye might ultimately be used. But let us hope she serves as more than a manipulative shorthand for viewers' emotional investment.