Armed with a good cast and an intriguing premise, “The Space Between Us” nevertheless fails to launch.

Peter Chelsom’s film was supposed to open in 2016 but didn’t. Despite the delay, it seems unfinished, choppy, the storytelling almost of an after-school special variety.

The story involves Gardner Elliot (Asa Butterfield), whose mother was one of the first astronauts to travel to Mars and establish a permanent colony. She brings more than her toothbrush, though; she was pregnant and dies during childbirth on the red planet. Sensing a public-relations disaster, leaders of the Genesis project, as the colonization company is called, decide to hide the truth from the public.

Thus we have Gardner growing up on Mars, the only human ever born there, his existence one big secret. He’s raised mostly by Kendra (Carla Gugino), who keeps tabs on him and sees him as the son that she, we learn, can never have — one of many melodramatic developments.

He’s also monitored on Earth by the Genesis staff, but not by Nathaniel Shepherd (Gary Oldman), who dreamed up the project. He left soon after Gardner’s birth. But the boy is 16 now and online friends with Tulsa (Britt Robertson), a foster kid, inexplicably unpopular at her high school. (With video chat, the distance between Mars and Earth is reduced considerably.) She and Gardner talk about various things, with Gardner telling her he has a disease and can’t leave his Manhattan penthouse, so he can’t visit. Tulsa doesn’t really buy his story, but there’s not much she can do about it.

But this isn’t enough for Gardner. He’s only ever met in person the small group of astronauts in the colony, and never been around anyone his own age. After much cajoling he convinces Kendra he should visit Earth, the place about which he has heard so much but never seen. He wants to find his father (a photo and some video footage may hold clues). He wants to see all of the places he’s only read about on his super-cool translucent computer.

And most of all he wants to meet Tulsa.

The problem is, his organs can’t stand the switch to Earth’s atmosphere for long. So escaping the Genesis facility and running away with Tulsa for an impossibly picturesque search for his father is more complicated and dangerous than it might be.

Luckily for them the adults, led by Nathaniel and Kendra, are inept when it comes to pursuit, allowing Gardner and Tulsa to form a quick relationship on the road. Potentially interesting storylines, like finding the shaman who married Gardner’s parents, come and go, explored only in passing. The story seems to be in as much of a hurry as the characters.

It’s a road-trip movie that travels to predictable places. A twist isn’t much of a surprise. That’s not a fatal flaw in a film aimed at tweens and young adults. The bigger problem here is the chemistry, or lack thereof, between Butterfield and Robertson. His Gardner is a goofy innocent (though his naiveté comes and goes), while her Tulsa is a rough-and-tumble outsider. Fine, opposites attract and all that. But Chelsom and Robertson make Tulsa abrasive, hard to relate to, even harder to like. It’s Robertson’s charm that prevents her from being completely unsympathetic.

The effect is to build a space between the characters and the audience — probably not the space the title intended.

Bill Goodykoontz, USA TODAY Network

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STX Entertainment presents a film directed by Peter Chelsom and written by Allan Loeb, Peter Chelsom and Tinker Lindsay. Rated PG-13 (for brief sensuality and language). Running time: 120 minutes. Opens Friday at local theaters.