Space junk is becoming a potential big problem. Earthlings have been using rocket technology to put satellites into orbit since 1957, and a lot of that stuff is still up there. The space surrounding Earth is getting too full of rocket garbage, things like abandoned rocket stages and old satellites, and eventually some of that stuff is going to cause a terrible accident.
Last Thursday, Oct. 15, a booster stage from a Chang Zheng 4C rocket almost collided with an old Soviet-era dysfunctional satellite called Cosmos 2004. Most near-Earth objects are in some sort of orbit, making their motion uniform and predictable. A collision between two large rocket pieces would send a tremendous amount of debris into unwanted trajectories, where additional collisions would be likely. Such an event could be catastrophic for the communications industry, which relies on satellites to move information around the world.