Humans� exploration of outer space has created thousands of fragments of rubbish, known as space debris. Around two thirds of catalogued objects originate from orbital break-ups; more than 240 explosions and fewer than 10 known collisions such as in 2009 between America�s Iridium-33 civil communications satellite and Russia�s Kosmos-2251 military satellite (which destroyed both and created a large amount of debris, more than 2200 tracked fragments).