Sandra Bullock’s Surprising Space Buddy Revealed!

You'd assume Sandra Bullock spoke with an expert or two to prepare for her epic space film "Gravity." But she did one better.

Bullock actually phoned up outer space.

NASA astronaut Dr. Catherine "Cady" Coleman and Bullock chatted multiple times while Coleman was orbiting the Earth on the International Space Station.

"It was actually funny to be calling [Bullock] on a cell-phone number," the 52-year-old astronaut said.

And, being the only female in tight quarters on a long trip, Coleman needed some girl bonding. "I'm up there with five guys and this was about three months into the six-month mission," Coleman told Yahoo Movies. "So this was like having a conversation with a girlfriend — and a really smart one that knew what she needed and what she wanted and also listened a lot to what I said so it was really pretty neat for me."

Dr. Catherine Coleman, left, and Sandra Bullock in 'Gravity'
Dr. Catherine Coleman, left, and Sandra Bullock in 'Gravity'

Upon learning of Coleman's space craving for some girl talk, Bullock joked, "Oh god, there's too much testosterone! … I hadn't even thought of it that way. I could imagine she needed some lady love."

Bullock tracked down Coleman through their respective siblings. (Bullock's sister and brother-in-law have business ties to Coleman's younger brother.) "Thankfully my brother-in-law did get us in touch with each other because I was grappling with exactly how the body [moves] in zero-G versus here," the 49-year-old Oscar winner told us.

And there calls were a feat in scheduling. "Our times don't always correspond and it took a little while to set it up," said Coleman.

[Related: Sandra Bullock Has the Best Day Ever as 'Gravity' Lifts Off]

But their long-distance connection proved fruitful: Coleman knew exactly what the actress needed to learn. "So many people think about what it's like to float up in space, but what is magic is we're like living in the land of Peter Pan," Coleman said, explaining that inside the safety of the space station, an astronaut can really let loose. "You just fly from place to place — and it is magical. I wanted her to understand that so that she would know that inside she didn't have to just kind of painfully run around — that she could just go."

Bullock dangled from strings, like a puppet, to mimic space movement during the making of "Gravity." "I kind of looked at it as modern interpretive dance," Bullock said of her effort to appear weightless. "What your body does instinctually here is not at all what it does in space. You had to train your body to move in an unnatural way that required muscle contractions and [reenacts her movements] to make it look like you're naturally going backwards where you've never done in a weird way."

[Related: 'Gravity': Hold Your Breath for the Year's Most Gripping Movie Trailer]

Bullock's interaction with the astronaut, which also included email correspondence and audio recordings of Coleman's space musings, proved enormously helpful for the star. "She said you could take a blade of your hair and put it against the wall and push off with it and that would make you move —that's how easily you could be moved around," Bullock recalled. "So imagine someone hitting you in space — you would go flying off."

"Gravity," directed by Alfonso Cuarón and also starring George Clooney, floats into theaters on October 4.

Watch 'Gravity' Clip — Off Structure:

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