article_snippet.sent: Since the first object, Sputnik 1, was launched into space 53 years ago, mankind has created a swarm of hundreds of thousands of items of debris.
article_snippet.sent: The rubbish circling the planet comes from old rockets, abandoned satellites and missile shrapnel.
article_snippet.sent: There are around 22,000 objects in orbit that are big enough for officials on the ground to track and countless more smaller ones that could do damage to human-carrying spaceships and valuable satellites.
article_snippet.sent: One major source of debris in the past was a Chinese anti-satellite missile test in 2007 that left an estimated 150,000 pieces of junk in the atmosphere.
article_snippet.sent: Accidental events have also contributed to the problem.
article_snippet.sent: In 2009 for instance there was a major crash between a U.S. communications satellite and a defunct Russian military probe over Siberia.
article_snippet.sent: Space debris, which is continuously accumulating as a result of human space activities, consists of artificial objects orbiting Earth.
article_snippet.sent: The number of objects nearly doubled from 2000 to 2014 and The number of objects have become a major obstacle to space development.
article_snippet.sent: The total mass of space debris is calculated to be about 3,000 tons.