The amount of orbital debris tracked by the US Space Surveillance Network jumped from 9, 949 cataloged objects in December 2006 to 16, 094 in July 2011, the National Research Council said.

美国全国研究委员会称，美国空间监测网跟踪并登记在册的太空垃圾数量在2006年12月为9949个，而在2011年7月就上升到了16094个。

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In 1997, the US National Research Council said that Nasa should carry out a thorough risk assessment to determine the likelihood that the space shuttle could be severely damaged by meteoroids and orbital debris.

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