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).
Scientists estimate the level of space debris orbiting Earth to be around 29,000 objects larger than 10 cm, 670 000 pieces larger than 1 cm, and more than 170 million above 1 mm. Any of these objects could harm an operational spacecraft, says Heiner Klinkrad, head of ESA�s Space Debris Office.
�A one centimetre object with a typical collision velocity of more than 50,000 kilometres an hour would come up with a kinetic energy upon impact that�s equivalent to an exploding hand grenade or a mid-range car running into the satellite with 60 km/h. One can imagine the effect.�
What was once a �giant leap� for mankind has brought with it consequences for the earth�s orbit. A problem being targeted by experts at the 6th European Conference on Space Debris (held 22-25 April at ESA�s European Space Operations Centre in Darmstadt, Germany.)
The ultimate goal is to prevent collisional cascading from setting in over the next few decades, the so called �Kessler syndrome�. Which would render some of orbit regions unusable in the long run.
Klinkrad says humans need to actively clear the debris they�ve created:
�The only way to solve the problem is to actively go there and remove mass from orbit, at a rate between five and 10 very big objects per year. This is a way to make sure, that we can control the environment.�
Methods of doing so are being studied by ESA and other space agencies in the world. They include the laborious task of using high energy lasers, fired from earth, which through energy absorption cause the fragment to vaporise.
Legal and political considerations underlie the issue of orbital space debris, and in some cases those issues are equally if not more onerous than the technical challenges surrounding its removal.
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