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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The Space Fence program is a multi-phase acquisition leading to the delivery of up to three globally positioned S-band radars capable of interoperation with the Space Surveillance Network.

太空护栏计划是一个多阶段的采购项目，交付3个全球定位S波段雷达系统，能够完成空间监测网互操作。

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America already has the world's most developed space monitoring system with a network of radars and telescopes. But its surveillance is patchy.

美国一直都拥有全球最发达的由雷达和望远镜网络组成的太空监测系统，但其侦察零散不全。

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The United States Space Surveillance Network is closely studying the collision involving the Russian satellite.

VOA: special.2009.04.01

Space debris is tracked by the United States Space Surveillance Network that uses radar that can detect an object the size of a pea at 400 miles.

BBC: By BBC News Online Science Editor Dr David Whitehouse

The U.S. military's Space Surveillance Network tracks roughly 22, 000 pieces of orbital debris larger than 4 inches (10 centimeters), which include broken satellite parts and spent rocket bodies.

MSN: Space Junk Hazards Force International Response