Getting a celebrity's cell phone number is generally understood to not be easy. But Cady Coleman found a way to get Sandra Bullock's. All she had to do was go into space.

Back in 2011 the NASA astronaut was on an expedition on the International Space Station while her brother Chris Coleman was on Earth – California, specifically – meeting a man whose sister-in-law happened to be Bullock. The two got to talking about what their family members did and decided they needed to connect Coleman and Bullock, who was about to star in Alfonso Cuarón's lost-in-space flick Gravity.

"It took a week or so to be able to talk [to her] just because we have an internet-protocol phone on the station that we can use to make calls, but I needed her cell phone number – you can't call us, we can call you," Coleman told WIRED, while not on a space station. "She's probably not so used to giving out that cell phone number so I had to write and say, 'You can give me your number, I won't give it away.'"

Eventually Coleman, who has logged more than 4,330 hours in space for NASA on two space shuttle missions and that stint on the ISS, was able to chat with Bullock – from space – and give her advice on everything from how to move in zero gravity to how to deal with the psychological toll of being unable to go home (something Bullock's Ryan Stone struggles with heavily while trying to get back to Earth in Gravity). She also began recording voice memos of things she thought might be helpful for the actress and sending her audio clips of helpful pointers.

"I'd be going about my work and think, 'Oh Sandra would probably want to know about this,'" Coleman said. "It did kind of make me fly around the space station with new eyes, because I was trying to be Sandra's eyes."

It worked. Bullock's performance in Gravity is shattering, and the film – in Coleman's eyes – is the most accurate portrayal of her actual experiences in space ever to make it to the big screen (minus the debris collisions). WIRED asked Coleman about her talks with Bullock, truth in Hollywood movies, and the importance of female astronauts in movies.

Cady Coleman spoke to Sandra Bullock about her experiences in space. Photo: NASA/Robert Markowitz

WIRED: Visually, Gravity feels incredibly life-like. How close is it – visually – to what you've experienced as an astronaut?

Cady Coleman: Something that's frustrating to me in my job is that I think it's a very special job. It's been a great privilege to go to space and to see the things that I see. Really, just to be up there doing work that you just know is really important in such a special place, and yet you don't really get to bring anybody that you know and love with you. A movie like this is a way for me to bring people to space. I will bring my mother to this. I will make everybody in my family go see this. I don't know what other people who haven't seen space think, but I feel like you get to see the view. I met Cuarón in the last couple weeks and he said, "I can't believe you've been to space!" And I said, "I can't believe you haven't been to space – since you made that movie."

WIRED: Was there anything that felt inauthentic?

Coleman: I couldn't help but look at some things and go, 'Oh, I don't know if we'd do that.' But that's not the point of the movie. I don't know if when Apollo 13 came out everyone ran around going 'Is that real? Is that real?' because [it wasn't] quite as sensational ... But people do ask [about how authentic Gravity is], and partly they're asking because, boy, if it's that real then why would anybody ever go? It's sensational. It's a lot of things that maybe could happen, but for them all to happen on the same day is more than coincidental. But they're all things that we consider at NASA.

WIRED: Yeah, space debris is obviously out there and a concern for space travel. How likely is it that astronauts would get pummeled by it the way they are in this movie?

Coleman: In Gravity there's the debris storm that we see in the trailers, and the astronauts are knocked free and they're spinning in space. Well, we think about that all the time when we're doing space walks because it's really the worst thing in the world that could happen. So, what do we do at NASA? We make sure it doesn't happen. It's a really real risk, but we do what we can to mitigate it. I think that's true of some of the other things you see in Gravity – what makes it scary in the movie is that it is real, but not real to that extent.

WIRED: What was your brother doing when he met Bullock's brother-in-law?

Coleman: My little brother is a wine guy in Sonoma. He's in the innovative wine-packaging business. Specialty-cask sampling is I think how I'm supposed to say it. As his sister I'm not allowed to say that he does really, really high-end wine in a bag, but that's what he does. He met Sandra Bullock's brother-in-law and they got together and figured out what their sisters and sister-in-laws did and got us together. Sandra and I did this interview together recently – it was specifically for NASA, to air on a NASA channel – and the interviewer said, 'How did you and Cady meet?' And she looks at me and she says, 'Wine.' I had to look at her and go, "We have to start again, because if we don’t they can't use it. We can't use an interview that starts with 'wine.'"

WIRED: So what kind of advice did you give Sandra Bullock when you called her from the ISS?

Coleman: My recollection is that we mostly talked about two kinds of things. One was physically how do you move up there? What do you hold on to? Are you fluid, are you angular, are you sort of dragging yourself around? The other was what it felt like to live in a place so far away from everybody that you know on the ground. And how do you deal with that separation and the fact that you can't just go home when you want.

WIRED: What is that strain like?

Coleman: Even the training is hard on your family – on your family life. It's hard to be away from your kid. [Ed. Note: Coleman has a husband and 13-year-old son.] Yet I feel like I was selected for this job and trained and invested a lot, and I believe in what we do and that it's the right thing for me to be at work when I'm at work and not at home. But I think there's an emotional price that you pay for that compartmentalization.

WIRED: Did you enjoy the fact that that lead in this film was a female astronaut?

Coleman: I did. I love it when the hero of a film is a woman. And it's a woman who uses her head and thinks out what she knows and when that doesn't work she thinks again and she's very persistent. These are a lot of qualities that I think are very important that are going to be portrayed to a bunch of 13-year-old girls and they're going to think they're normal. They're going to realize that it's normal to be the hero. That it could be them – the hero could be them.

The number of people that ask me if I feel bad about leaving my kid at home is too many to count, right? Sometimes I resent that they don't ask the guys the same question, which is insulting to the guys who also miss their kids. The answer is, "Yes, I feel really bad, but it is also the right thing to do."

WIRED: Did any of that thinking inform your conversations with Bullock?

Coleman: There has to be a little part of her that is thinking when we first talked, "Ok, I'm talking to a woman that's just like left her kid on the planet and went away and didn't think anything of it. What kind of woman can do that?" I think we went from that to realizing that I'm the same kind of woman that feels badly about that but it feels like the right thing to do. I think making that human part of living in space … It's about the whole person up there. The very humanness of being up there was very clear for me and I believe that's some of what she got from talking to me. I hope so.