With its sophisticated predictive model, NASA can peer hundreds of years into the future at Earth-orbiting objects that could crash into each other.
In September, a piece of debris broke off from a 19-year-old nonoperational NASA satellite 330 miles up in the sky. The United States Space Surveillance Network (SSN), which is responsible for monitoring the more than 22,000 satellites and other objects in orbit, detected the event, plotted out the fragment's orbital path, and determined that it was headed for the International Space Station (ISS).
If it hit the $100 billion laboratory, the junk could cause catastrophic damage. Upon receiving the warning, NASA decided to maneuver the spacecraft out of the path of the debris, a task that it now performs about twice a year.