Space debris

Space debris, also known as space junk, are any of the tens of thousands of small artificial objects in orbit around Earth that are a result of the planet's space programs over the years. They consist of everything from entire spent rocket stages and defunct satellites to small screws, fragments of metal, flecks of paint, and other small particles. Debris are most concentrated in low Earth orbit, though some extends out past geosynchronous orbit.

Space debris has become a growing concern in recent years, since collisions at orbital velocities can be highly damaging to functioning satellites and can also produce even more space debris in the process. Most satellites are now armored to deal with this hazard. Proposals have been made for ways to "sweep" space debris back into Earth's atmosphere, including automated tugs, lasers to vaporize or nudge particles into rapidly-decaying orbits, or huge aerogel blobs to absorb impacting junk and eventually fall out of orbit with them trapped inside. However, currently most effort is being devoted to prevention; satellites are deliberately deorbited at the end of their useful lifespan, or moved to "graveyard orbits" where no valuable functioning satellites are present.