For a guy who plays a new kind of alien — an Earthling raised on Mars — in a movie all about space travel, you’d think Asa Butterfield would be more adventurous.

Sure, he races rovers across the Martian desertscape, and hurtles toward Earth in the new film “The Space Between Us.” But when it comes to something as simple as going up in a hot-air balloon, the 19-year-old British actor and “Hugo” star gets quiet.

“Actually, I don’t think I’d do that,” he says, chuckling. “I’m a bit scared of going up in a balloon. It’s one thing if you go up with a massive engine, but a balloon filled with gas seems ridiculous.”

“Space,” directed by Peter Chelsom, hits theaters Feb. 3. It follows teenager Gardner Elliot (Butterfield), born to an unexpectedly pregnant female astronaut on Mars, on an arduous journey back to Earth to meet his pen pal (um, make that interplanetary Skype pal) Tulsa (Britt Robertson). The film was shot in and around Albuquerque during its famed Hot Air Balloon Festival, and the balloons make a brief cameo, floating by in the background of one scene. It’s a form of travel that seems archaic now, eclipsed by cars, bullet trains, jets and . . . maybe soon . . . rocket ships — if we’re to believe this film.

And, as it turns out, there are plenty of reasons why you should.

When producer Richard Barton Lewis first began developing this story in 2006, the idea of travel to Mars was “plausible, but a pipe dream,” he says. “Now it’s going to happen,” he notes, citing space-travel enterprises like Elon Musk’s SpaceX and Richard Branson’s Virgin Galactic. “My joke has been that I just want to get this movie into theaters before we actually land on Mars.”

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Easier said than done. It took 11 years to bring the story to life. Then came the task of picking a release date. “Space,” originally slated to open last summer, was bumped to December, then to February after its distributor, STX Entertainment, realized that going up against December juggernaut “Rogue One: A Star Wars Story” was probably not a good idea.

The film is an intriguing amalgam of teen adventure, corporate intrigue (Gary Oldman plays an inscrutable CEO and space-travel pioneer along the lines of Musk or Branson) and Popular Science article.

To research the finer points of how we’ll get to Mars and “terraform” the planet (creating an atmosphere amenable to humans), Lewis consulted with astronauts, scientists and visionaries, including Musk, and Scott Hubbard, the former “Mars czar” who once led NASA’s plans to reach the Red Planet. The film’s opening scene was even shot at Virgin Galactic’s spaceport, Branson’s New Mexico facility and blastoff point for his much-ballyhooed commercial trips to space.

“We’re the only movie to ever shoot there,” Lewis says proudly.

Inspired by gripping (but scientifically credible) films like Robert Wise’s 1971 “The Andromeda Strain” and Steven Spielberg’s 1977 “Close Encounters of the Third Kind,” Lewis says his goal is to make movies that entertain, and educate.

Butterfield did his part, studying up on gravity, though he had a head-start, thanks to his role in the 2013 sci-fi film “Ender’s Game.”

“We worked with lots of harnesses there to simulate zero-gravity,” he says.

In “Space,” the big challenge was “capturing the physicality of the character,” he says. For someone who’s only lived on Mars, where gravity is about one-third of that on Earth, “to then return to Earth and do the simplest things would be incredibly difficult,” he says. “It would affect the way you move, walk, everything.”

Here’s a little Martian Biology 101, for those who may be rusty. A woman on Mars who weighs, say, 120 pounds would come to Earth and — blam! — suddenly weigh about 320. A 185-pound guy on Mars leaps to nearly 500 pounds here. Each body is the same size. It’s just the force from gravity that’s different. Imagine how strange your body would feel, how much harder to move.

And that’s just for starters. Gravity affects anatomy, from heart size to bone strength. (Bones won’t need to be as strong on Mars, given its weaker gravitational pressure, so your skeleton would store less calcium. Not a big deal, unless you pop back to Earth, where your bones will seem like wet noodles.)

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These are just some of the issues real-life space-travel entrepreneurs are sorting out. Butterfield’s character undergoes surgery to encase his bones in a hard skeletal covering, like scaffolding, so he’ll be able to walk on Earth. It’s all part of his struggle to get the girl — or at least meet her.

In other sci-fi films, heroes leap from planet to planet, swinging light sabers, no problem.

“Look, it’s an adventure, a feel-good movie,” Lewis says, “but we worked hard to make sure the science is as valid as possible.”

Given all he knows about space travel, would Lewis go?

He’s not keen on the idea. But his son — now studying astrophysics at Stanford — is committed to it. “He’s dragged me hang-gliding, paragliding, and I went up with him when he flew a Cessna at 13,” Lewis says. “If he said, ‘Hey, Dad, ya gotta come along,’ then, yeah, I’m going.”

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Butterfield is more circumspect.

“I’d like to go to space, but Mars is quite far,” he says. “I don’t know if I’m up for that or not. Maybe. I’ll wait for a few people to do it first — make sure it’s safe. It’s a long trip.”