One of the trailers:
While space debris is unlikely to arrive in such pestilential swarms as the movie shows, and probably wouldn't be visible to the eye as it approached (see excerpt from my article below -- the closing speeds are too fast), whoever researched the Gravity script did get some important principles correct. And in any case the movie (particularly in 3-D) apparently does an amazing job of giving the viewer the sense of being up there, and out there.
Setting aside exaggeration for effect, the writers are correct that the biggest threat to manned spacecraft in low earth orbit (particularly the ISS) is man-made debris. It's also worth noting that NASA regarded servicing the Hubble Space Telescope with the Shuttle rather risky (at least after the Columbia loss) because the shuttle had no easily accessible safe haven. The Hubble is in a much higher orbit than the space station.
Here's a link to a NASA report on dangers from space debris.
Following is the introduction from my 1999 space-debris article for Smithsonian on space debris. Coincidentally, that research brought me nose-to-nose with Columbia.
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ANYBODY WHO BELIEVES THAT SPACE IS AS empty as it looks in the movies should spend a few hours with Justin Kerr of NASA and Ronnie Bernhard of Lockheed Martin. It's June and both scientists have flown in from Houston to inspect the orbiter Columbia, which sits in Bay 3 at the Kennedy Space Center's Orbiter Processing Facility. I'm stretched out on an aluminum work platform by Columbia's windshield, under strict orders not to drop pens or notebooks or wedding rings that might damage the fragile tiles below.
Kerr hunkers down to my left and crawls through a playhouse-size aluminum entryway, emerging onto a catwalk with a nice view of Columbia's spacious payload bay. He grasps a lab notebook and a sampling kit, including a chopstick, a bamboo skewer and an orange stick. He directs my attention to a pair of tiny dark craters, each about twice the size of a sharp pencil tip, bored into a white metal frame that holds up one of the spacecraft's antennas. Kerr uses a bamboo stick and tape to gather up the smoky residue from each of the craters. He wraps up the tape and each stick to preserve the soot for microscopic scrutiny.
A shout comes from a platform one level beneath us: others on the NASA debris team have found another impact crater, this time on the right payload door. As we head down, I learn that NASA has logged io6 significant hits on Columbia from this single mission, most of them caused by unwanted man-made particles in orbit. (On most missions, minor damage means that at least one outer layer of window glass is replaced.) Bernhard is crouched under the open door, craning awkwardly to look straight overhead at the white insulated surface with a magnifying glass. He suggests I take a look. Through the tear I see goldish-brown felt that's been singed by the impact; on the white surface of the door smoky soot trails off one side.
These particular craters look pretty small to me, and I ask Bernhard if tiny but fast particles mean much. Yes, indeed, he says.
During a mission in 1995, Columbia took a hit in a payload door that made a gash almost an inch across. If that piece had crossed into the payload bay and punched a big enough hole in the cooling system there, Houston controllers would have ordered the ship back to Earth immediately. One reason it didn't hit at a bad spot was that the NASA debris squad had predicted the risk beforehand, based on earlier shuttle flights, and suggested keeping one payload door partially closed to help shield the payload bay. Bernhard says that, from the metals found in the crater, the culprit on that mission was probably a fragment of circuit board. Where it came from nobody could say, but an explosion is likely. Space has seen its share of silent blasts, some of them quite recently; in 1996 a Pegasus rocket exploded due to a fuel-tank explosion and propelled into orbit at least 700 pieces more than four inches across.
Science writers of the 1950s vividly described the risks to future spacefarers from rocky micrometeoroids near Earth, but the prognosticators missed the boat on what has turned out as a bigger deal, safety-wise. Near Earth, artificial meteoroids now pose a greater risk than the natural stuff. Over the decades humanity has gone Saturn one better by putting up not just a ring but a spherical shell of glittery objects around the planet. It's a layer of camera lens caps, spent rocket boosters, bolts, nuts, buckets of garbage, and countless flecks of dislodged paint and particles of solid fuel from booster rockets.
Even full-sized spacecraft that can be tracked reliably with radar have begun to cross paths, causing encounters that while rare are positively alarming. During his four-month stay on the Mir space station, astronaut Mike Foale received three warnings of approaching space traffic. In the last incident, an obsolete American satellite called MSTI-2 passed less than a thousand meters from Mir.
At the request of Russian controllers, Foale interrupted his exercise-bike workout to join the cosmonauts in the Soyuz (a Russian spacecraft that can return the cosmonauts to Earth) for a few minutes as a safety measure in case Mir was punctured. "We always looked outside [during the close passes] to spot them and it was inevitably futile," he says now. "Imagine trying to see a small dot ten kilometers away over your left shoulder, and a second later it's right next to you, and another second later it's ten kilometers over your right shoulder."