IF Sandra Bullock ever gives up the day job, then she can always turn her hand to a spot of acrobatic work following her experience making Gravity.
"It was completely new, more like being a member of Cirque Du Soleil," says the actress as she reflects on the heart-pounding space thriller.
She stars as Dr Ryan Stone, a brilliant medical engineer on her first shuttle mission, alongside veteran astronaut Matt Kowalski, played by George Clooney.
They're carrying out a routine mission when disaster strikes and the shuttle's destroyed, leaving the pair tethered to nothing but each other and spiralling into the ether.
Much like James Cameron's Avatar, the movie has set a new bar in film-making, using alien technology and involving, as Bullock puts it, "the most bizarre system of contraptions" in order to create the illusion of weightlessness.
There was the Light Box for instance, a 20ft by 10ft elevated LED box "in a sea of blackness", in which Bullock would be clamped from the waist down.
Within this, striking images of Earth, the International Space Station and distant stars, provided by NASA, were projected onto the walls, giving the actors the perspective of their characters.
"What blew me away is how the astronauts are able to show this world of ours to the viewer.
"I'd never seen it like that before, and felt guilty that I'd never appreciated it as much as I do now," says Bullock.
There was also a 12-wire system, "where you're basically being manipulated by puppeteers to simulate flying around space," she adds.
Bullock also worked intensively with a movement coach to achieve that zero-gravity effect, which required her to move more slowly but speak in a normal tempo.
She says Gravity is the biggest challenge she's set herself professionally.
"I loved it. I mean, I didn't love it while we were making it, every day was uncomfortable, but I appreciated that," she adds, laughing.
"I appreciate not being in my comfort zone, because that means I've got as far away from myself as possible. And I learnt that unlocks things that scare you, frustrate you, makes you feel so insecure, but it also forces you to dig very deep."
Bullock, who came to prominence in the 1994 action movie Speed, has eased her work schedule since winning a Best Actress Oscar for The Blind Side in 2010 and adopting her son Louis, now three years old.
But she couldn't resist this project, which is directed by the Mexican film-maker Alfonso Cuaron. "I don't think I've ever done a movie that didn't have a mix of handprints along the way, because a movie takes forever to make, but it was the most collaborative experience I've ever had," she says.
"I've admired Alfonso for so long, but working with him exceeded all my expectations. He's a master film-maker and collaborator who makes everyone around him want to give their best."
That said, she confesses that the movie "scared me on every level" – not least because it was initially going to be shot in what is known as the 'Vomit Comet', a plane that plummets out of the sky to achieve weightlessness.
"I'm afraid of flying, it's one of my greatest fears, so I thought it was maybe time to get over that, but I was grateful we didn't do it that way," notes the actress.
It's little surprise that she has no desire to actually go to space. "I will not be booking a ticket, unless when I'm 80, my son says, 'I'd like to go to space with you'."
As part of her preparation, she spoke to astronauts about their experiences, and it proved revelatory.
"I used to think that astronauts wanted to go into space for the thrill and adventure, but when I spoke to them I was so moved by their deep, deep love of that world and the beauty of Earth from their perspective, seeing the oceans and mountain ranges and the lights of the cities.
"It's amazing to realise how small we are in this massive universe."
Indeed, right now, there are people orbiting hundreds of miles above Earth and coping with the inherent dangers of space flight, which have grown in the decades since man began venturing into space. The refuse from past missions and defunct satellites has formed a debris field that can cause disaster in an instant.
"It's heartbreaking to think not only of the destruction of this planet, but also about what we don't see: the trash that is literally orbiting above us," says Bullock.
The premise becomes the catalyst for a harrowing fight for survival in Gravity.
"I think it's a story about what makes us try, when it seems there is no light at the end of the tunnel," she says. "What is it that makes you go that bit extra, just in case it was worth the effort to try?"
We discover that Stone has suffered a devastating loss in her life, and when Bullock started delving into the character, she asked herself what would she do in that position. "I'd probably do exactly the same thing Ryan did. She withdrew," says the actress, who discussed Stone's backstory at length with Cuaron.
"It was clear we shared an understanding of her and also had the same set of questions. Why do we retreat when tragedy strikes, when being with others is what can save you?
"In a way, what Stone goes through is a compelling allegory for, 'Be careful what you wish for'. She wanted to be alone and she got it." As a result of the script, which sees Stone stranded in space, Bullock spent the majority of the shoot in a solitary fashion.
And as frustrating and bizarre as the experience was, she's glad "no one else got to do it" first, not least because there's already Oscar buzz surfacing.
"Going into this film, I had no idea what I was capable of on so many levels, physically, emotionally and mentally," says Bullock. "It was body changing, mind changing, mind bending. I just hope people who come on this amazing ride will leave the theatre also feeling transformed."
Gravity is released on Thursday