双语：太空垃圾数量已达“临界点”

 　　The amount of debris¹ orbiting the Earth has reached "a tipping point" for collisions, which would in turn generate more of the debris that threatens astronauts and satellites, according to a US study released on Thursday。

　　NASA needs a new strategic plan for mitigating² the hazards posed by spent rocket bodies, discarded satellites

　　and thousands of other pieces of junk flying around the planet at speeds of 17,500 miles (28,164 kilomtres) per hour, the National Research Council said in the study。

　　The council is one of the private, nonprofit US national academies that provide expert advice on scientific problems。

　　Orbital debris poses a threat to the approximately 1,000 operational commercial, military and civilian³ satellites orbiting the Earth -- part of a global industry that generated $168 billion in revenues last year, Satellite Industry Association figures show。

　　The world's first space smashup

　　occurred in 2009 when a working Iridium communications satellite and a non-operational Russian satellite collided 490 miles (789 km) over Siberia, generating thousands of new pieces of orbital debris。

　　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。

　　The surveillance network tracks objects approximately 10 centimeters in diameter and larger。

　　Some computer models show the amount of orbital debris "has reached a tipping point, with enough currently in orbit to continually collide and create even more debris, raising the risk of spacecraft failures," the research council said in a statement released Thursday as part its 182-page report。

　　"The current space environment is growing increasingly hazardous⁴ to spacecraft and astronauts," Donald Kessler, the former head of NASA's Orbital Debris Program Office who chaired the study team, said in a statement。

　　据美国上周四发布的一份报告，地球轨道上太空垃圾的数量已经达到“临界点”，有撞击风险，而后可能产生更多碎片，威胁宇航员和人造卫星的安全。

　　美国全国研究委员会在报告中称，美国宇航局需要制定新的战略计划，以减小火箭残骸、报废卫星、以及数千块其它太空垃圾的危害。这些轨道太空垃圾时速高达1.75万英里(28164公里)。

1 debris   

n.瓦砾堆，废墟，碎片

参考例句：

• After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
• Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上，导致蛀牙。

2 mitigating   

v.减轻，缓和( mitigate的现在分词 )

参考例句：

• Are there any mitigating circumstances in this case ? 本案中是否有任何情况可以减轻被告的罪行？ 来自辞典例句
• A sentencing judge is required to consider any mitigating circumstances befor imposing the death penalty. 在处死刑之前，要求量刑法官必须考虑是否有任何减轻罪行之情节。 来自口语例句

3 civilian   

adj.平民的，民用的，民众的

参考例句：

• There is no reliable information about civilian casualties.关于平民的伤亡还没有确凿的信息。
• He resigned his commission to take up a civilian job.他辞去军职而从事平民工作。

4 hazardous   

adj.(有)危险的，冒险的；碰运气的

参考例句：

• These conditions are very hazardous for shipping.这些情况对航海非常不利。
• Everybody said that it was a hazardous investment.大家都说那是一次危险的投资。