This is astronaut Leroy Chiao.
Ryan Stone (Sandra Bullock) is on a spacewalk with Matt Kowalski (George Clooney) to fix the Hubble Space Telescope.
Reality: The Hubble was designed to be serviced, so a repair mission isn't unusual. But maintenance usually requires removing larger modules with connectors, not individual circuit boards. "Something similar did happen, but normally the operations are planned so you wouldn’t have to do that sort of delicate work in a suit," says Chiao.
Debris from a neighboring satellite knocks out all communication and sends Stone tumbling into the pit of space.
Reality: NASA closely monitors any impending obstacles, and missions are planned to minimize any chance of catastrophe. "There’s a lot of stuff in space, but frankly, it’s still a pretty big sky," says Chiao. It's unlikely to run into something even if things aren't being monitored — especially if the debris comes from an entirely different orbit.
Kowalski jets his way over to Stone and brings her back to the shuttle.
Reality: Manned Maneuvering Units, hand-controlled and propelled by nitrogen, were used for three missions in 1984 but were never recertified after the Challenger accident in 1986. Astronauts are always tethered.
Kowalski finds and rescues Stone.
Reality: Helmets have very limited visibility. Chiao's scariest moment was when his boots became disengaged from the robotic arm that was holding him.
"I knew I was drifting away from the shuttle and the station, and I knew intellectually that I had connected my cable, but I couldn’t see it," he says. "I was rotating very slowly and had to wait about 15 seconds before my body rotated to the point where I could see that I was still connected."
Putting on a Suit
Taking Off a Suit
Stone is only wearing boy shorts and a tank top under her suit.
Reality: Astronauts layer like incontinent Midwesterners. That includes thermal underwear and a maximum absorbency garment (i.e. diaper). They also wear a liquid cooling garment with sewn-in tubes that circulate cooling water to get heat away from your body, which race-car drivers have adapted.