Space Junk Expert Donald Kessler: We're Polluting Space Faster Than Nature Can Clean It Up (VIDEO)

In the sci-fi flick "Gravity," slated to hit theaters on Oct. 4, debris from a satellite crashes into a space shuttle, leaving astronauts played by Sandra Bullock and George Clooney stranded in space. Could such a scary scenario actually happen?

Don Kessler, NASA's retired chief scientist for orbital debris, joined HuffPost Live to talk about the growing problem of space junk -- and made it clear that it really does pose a threat to spacecraft and astronauts. Check out a video clip from the discussion above.

"We've reached a point where the collision rate between these larger objects, generating debris, is faster than it can be cleaned out by the natural environment," Kessler said.

The so-called "Kessler Syndrome" refers to a situation in which the density of objects in orbit is high enough that collisions between objects cause a cascade effect -- with each collision generating more debris that leads to more collisions. Yikes.

What can be done to keep this from happening? Kessler, for whom the syndrome is named, said, "The only way to do it is to bring back the larger objects ... If you want to stop this collisional cascading process, you have to bring back satellites, and we don't know how to do that."

Or, Kessler added, "You have to do it the old-fashioned way -- just go up and start picking up things one at a time."

To hear more from Donald Kessler, watch the full segment HERE.

Orbital Debris Surrounding Earth