Just take a moment to consider: we could be trapped on Earth by our trash in space.

In 1978, NASA scientist Donald Kessler wrote a paper on how the problem of space junk is prone to a domino effect. The quantity of space trash is continually growing as missiles destroy satellites, dead satellites crash into live ones, and rockets jettison engines. These and other activities leave behind observable hunks, along with tiny bits of paint, rock and metal that regularly collide with operational space gear at speeds of up to 17,500 mph (ten times faster than a bullet).

There are 500,000 pieces of space debris the size of a marble or larger, according to NASA. Kessler wrote that the more bits there are in space, the more likely those bits are to crash into each other. Crashes create more bits, which creates more crashes, in what's called an ablation cascade. At a certain point, there will be so many bits hurtling around the Earth that it will become effectively impossible to put anything else in space.

However, by modeling that trash, engineers can find the most efficient plan to clean it up.