Space debris (also known as “orbital debris,” “space junk” or “space waste”) presents a serious collision risk for launch vehicles, orbital vehicles and satellites. Space debris can range in size from spent solid rocket motor cases to nuts, bolts and tiny bits of old launch vehicles to entire spent rocket stages and defunct satellites. However, the size of the debris is essentially irrelevant, since typical collision speeds are on the order of a few to tens of kilometers per second. At those speeds, even tiny debris can punch into functioning vehicles and satellites, sometimes breaching their skin, crippling their electronics and compromising their missions.
The problem of space debris has only become worse over the decades. While the orbits of space debris do eventually decay, and old space debris reenters the Earth's atmosphere and is destroyed, far more debris is added each year through new vehicle launches and satellite failures than is removed through reentry.
The conventional response to the problem of space debris has consisted of avoiding the creation of further space debris, using sacrificial layers of protection (e.g., foil) to protect sensitive equipment, altogether steering clear of known space debris and relying on orbital decay to remove space debris. Unfortunately, foil and extra fuel add weight and complexity to space structures and do not guarantee protection, especially from larger debris; much of the smaller space debris is undetectable and so cannot be avoided; and orbital decay takes an unreasonable amount of time (sometimes decades) to happen. Consequently, space debris remains a serious threat to further space exploration and exploitation.