Space debris is a growing problem, and not just in Earth orbit.
Once a week, on average, a spacecraft (or part of one) falls back into Earth's atmosphere; most of these objects are empty rocket stages, but some are dead satellites whose low orbits finally decayed enough for them to slip into the atmosphere. They're basically like human-made meteors, but most of them don't survive long. This is because of the heat and shredding force that come with high-speed collisions with the air. However, some bits of debris from the objects can exist long enough to plummet through the sky, ranging from dust-mote-sized particles to whole propellant tanks. And this can be a big problem.
