James Cameron called it "the best space film ever done." Groundbreaking, piss-your-pants space spectacle Gravity stars Sandra Bullock and George Clooney as two astronauts who struggle to survive in zero-G space after their shuttle is destroyed by debris. It's a vertiginous imagining of what it would feel like to almost die above the Earth, tumbling helmet-over-boots and running out of oxygen, as tiny bits of speeding shrapnel threaten to perforate your face.
The movie is the brainchild of Alfonso Cuarón, director of Y Tu Mamá También and Children of Men. "I've always been a very low-tech kind of guy," says Cuarón, catching his breath on a couch in a Toronto hotel, visibly exhausted by rounds of schmoozing at the Toronto International Film Festival. "I got my first computer, like, five years ago."
That ignorance may have been the 51-year-old filmmaker's greatest advantage: When he started working on the film, in 2009, he didn't know what wasn't possible. "We had a pleasurable month writing the script," says Cuarón's 30-year-old son, Jonas. "A lot of our drive was, 'Let's do something simple: only two characters in space, no extras. It's gonna be so easy.' Four-and-a-half years later . . ."
In Gravity, Cuarón uses realistic, continuously moving shots that seem to stretch on forever. It took months of trial and error to achieve the movie's disorienting, enveloping feel: Working with his longtime cinematographer Emmanuel "Chivo" Lubezki, Cuarón explored underwater tanks, mirrors, green-screen and those ubiquitous wire rigs. "We even tried the Vomit Comet," says Cuarón, referring to the high-altitude jet used to simulate zero gravity in Apollo 13. "The stunt guy threw up. He was like, 'Get me out of here!' Everything just looked so bad."
Eventually, Lubezki tried the idea of moving lights around a stationary actor, which would make it appear that the actor was moving; the background could be finished in post-production. The only problem was that stage lights are huge, and setting them up on cranes and tracks to move them fast enough was dangerous and cumbersome. Finally, the team devised a 14 by-nine-foot "light box" – a.k.a. "The Cage" – composed of six huge LED panels surrounding the actors, who were strapped into harnesses. The LED pixels could simulate the light emanated by swirling stars and cascading debris, lighting the actors as if they were spinning through space.
Cuarón also had help from automated minions. "We'd been developing this technology with the robots they use to build cars," he says. They installed a camera on a programmable, two-ton manufacturing robot, which the crew nicknamed Iris. Iris would race along a track outside the cube and reach through strategic openings to create a moving, roving camera that could swivel 360 degrees. "The intention was that you would be a third character, floating with our heroes," Cuarón says.
To make it work, Cuarón and his team had to choreograph and program every single shot in advance – the LED screens, Iris and two more robots that simulated the light of the sun and Earth. In a sense, the entire film was in the can before the first day on set.
"You're inventing technology and don't know if it's going to work," Cuarón says. "The night before shooting, it didn't work. The day we started, it worked."
"It was scary," says producer David Heyman. "Because if the two-ton robot motors toward an actor in a rig and it doesn't stop – well, it's not a pretty ending."
After all that, it was a shoot in an underwater tank that became one of the scariest days: "I had to get out of the space suit underwater, and I started to panic because I couldn't get out fast enough," says Bullock. "The rescue divers were far away because of how wide the shot was, and it felt like minutes before they got to me."
Bullock is the movie's central character, despite the fact that Cuarón says some executives argued for a big male star. "I was like, 'No, it's a woman,'" he says. "We wanted to stay completely away from macho heroism." (Although Cuarón admits Bullock was a bit more macho than himself: "Sandy says, 'She shouldn't scream.' I said, 'Sandra, I would scream if I was there.' She said, 'Yes, but you're a wimp.'")
"Poor Sandra, she was alone there in that box," says Cuarón. "All the communications were through headphones in her suit. I was literally 15 minutes away, with banks of computers and stuff, communicating with her through radio, like I was Houston and she was an astronaut."
Once the light cube was closed, it took about 25 minutes to "open the cube, close it again, and adjust all the little things on the rig," Cuarón says, so Bullock largely chose to stay strapped in, isolated for up to 11 hours a day. To keep her spirits up through days of minuscule technical calibrations and computer glitches, Cuarón chose an atmospheric playlist for her headphones and had some fun, occasionally surprising her by filling the LED screens with images of her kid.
The final result is that rarest of things: a high-tech film that actually lives up to the hyperbole, and justifies the 3D-movie ticket surcharge. Cuarón says it all comes from his Sixties childhood dreams of the space program. "I would stay awake late or wake up very early to see the launch of a rocket," he says. "I would pretend that these guys are in a little cocoon, alone, surrounded by nothingness. I had my cheesy plastic capsule, a toy, that would have a little light inside, and I would play with it at night, with all lights off." Cuarón leans back on the sofa and holds his fingers up, as if holding his old toy up against the Toronto skyline: "There was just something so fragile, and daring." He drops his hand. "And so exciting."
This story is from the October 10th, 2013 issue of Rolling Stone.