VOA标准英语2011--Plummeting US Satellite to Hit Earth Fri

Plummeting US Satellite to Hit Earth Friday

NASA launched the Upper Atmosphere Research Satellite (UARS) 20 years ago this month. And now that bus-sized satellite is plunging¹ toward Earth.
Mark Matney, an orbital debris² scientist at NASA's Johnson Space Center in Texas, says UARS will likely reenter the atmosphere on September 23, 2011. He says scientists will be able to narrow the time frame as it gets closer.
As far as where it will crash, Matney says UARS passes over the Earth between 57 degrees north latitude³ and 57 degrees south latitude.
"Everything from Canada down to the tip of South America, and from Siberia down to the tip of Africa and Australia [could be where the satellite lands]," says Matney. "So, it's quite a bit of land."
It is also quite a bit of ocean. Given that more than two-thirds of the planet is covered by water, space debris usually lands with a splash.
Still, there is the chance that UARS could land with a thud, although NASA's Matney says this week's satellite reentry is not cause for great concern.
Take Cover?
"If you talk about the probability of you getting hit, it's something like one in trillions, so actually the odds⁴ of you getting hit is quite small," Matney says. "So, I don't think anybody needs to be unduly⁵ concerned about it."
NASA says it has no reports of a person being injured or property being significantly damaged by reentering debris. But there was an incident in 1997.
"There actually was a lady in Oklahoma who was hit by a piece of very light debris from a reentering satellite, but it didn't hurt her. It was a piece of insulation⁶. She was out jogging, and it hit her," recalls Matney. "That same reentry dropped two tanks over Texas."
Matney says debris reentry is a common occurrence, averaging about one piece per day, but that the pieces usually are small. But he says this will be the first time in 30 years that a U.S. space agency satellite of this size will have crashed back to Earth.
Most of UARS is expected to burn up in the atmosphere.
Computer Modeling
Even though officials at NASA and the Department of Defense⁷ cannot yet provide a precise landing footprint, Matney says the science of figuring out what will land is exacting⁸.
"We actually take time to get the original specifications⁹, to get the different parts of the spacecraft, the material types, their shape, their mass," explains Matney. "And we actually have computer programs that model the dynamics¹⁰ as it begins to heat up and break up and look at the temperatures those pieces reach and whether they reach the melting point of the metal."
For instance, he says that because of aluminum¹¹'s relatively¹² low melting temperature, aluminum objects usually disintegrate¹³ before they reach the surface of the Earth.
NASA expects 26 "potentially hazardous¹⁴" pieces of UARS to reach the ground, most of them made of titanium, stainless¹⁵ steel or beryllium, which have high melting points. These pieces of debris include batteries, wheel rims¹⁶ and empty fuel tanks. UARS debris is expected to range in mass from 0.6 to 158 kilograms.
Orbital Debris Management
NASA's Orbital Debris Program works to reduce the number of large debris pieces in orbit. One aim is to prevent pieces of space junk from colliding and breaking into smaller pieces as well as to keep active satellites and spacecraft safe.
NASA's Mark Matney says the space agency took steps in 2005 to decommission the Upper Atmosphere Research Satellite.
"With what fuel was left on board UARS, we lowered the orbit to a point that we actually shaved 20 years off its lifetime, off its orbit lifetime, to try to remove it from orbit a bit sooner," the scientist explains.
Finders Keepers?
NASA officials say people should call their local law enforcement agencies if they find parts of the satellite. Matney cautions that although the pieces are not toxic¹⁷, they might have sharp edges. Even though it is commonly referred to as "space junk," the debris still belongs to the country that owns the craft, in this case, the United States.

1 plunging   

adj.跳进的，突进的v.颠簸( plunge的现在分词 )；暴跌；骤降；突降

参考例句：

• War broke out again, plunging the people into misery and suffering. 战祸复发，生灵涂炭。 来自《现代汉英综合大词典》
• He is plunging into an abyss of despair. 他陷入了绝望的深渊。 来自《简明英汉词典》

2 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。

3 latitude   

n.纬度，行动或言论的自由(范围)，(pl.)地区

参考例句：

• The latitude of the island is 20 degrees south.该岛的纬度是南纬20度。
• The two cities are at approximately the same latitude.这两个城市差不多位于同一纬度上。

4 odds   

n.让步，机率，可能性，比率；胜败优劣之别

参考例句：

• The odds are 5 to 1 that she will win.她获胜的机会是五比一。
• Do you know the odds of winning the lottery once?你知道赢得一次彩票的几率多大吗？

5 unduly   

adv.过度地，不适当地

参考例句：

• He did not sound unduly worried at the prospect.他的口气听上去对前景并不十分担忧。
• He argued that the law was unduly restrictive.他辩称法律的约束性有些过分了。

6 insulation   

n.隔离；绝缘；隔热

参考例句：

• Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
• It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。

7 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

8 exacting   

adj.苛求的，要求严格的

参考例句：

• He must remember the letters and symbols with exacting precision.他必须以严格的精度记住每个字母和符号。
• The public has been more exacting in its demands as time has passed.随着时间的推移，公众的要求更趋严格。

9 specifications   

n.规格；载明；详述；（产品等的）说明书；说明书( specification的名词复数 )；详细的计划书；载明；详述

参考例句：

• Our work must answer the specifications laid down. 我们的工作应符合所定的规范。 来自《简明英汉词典》
• This sketch does not conform with the specifications. 图文不符。 来自《现代汉英综合大词典》

10 dynamics   

n.力学，动力学，动力，原动力；动态

参考例句：

• In order to succeed,you must master complicated knowledge of dynamics.要取得胜利，你必须掌握很复杂的动力学知识。
• Dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。

11 aluminum   

n.(aluminium)铝

参考例句：

• The aluminum sheets cannot be too much thicker than 0.04 inches.铝板厚度不能超过0.04英寸。
• During the launch phase,it would ride in a protective aluminum shell.在发射阶段，它盛在一只保护的铝壳里。

12 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

13 disintegrate   

v.瓦解，解体，（使）碎裂，（使）粉碎

参考例句：

• The older strata gradually disintegrate.较老的岩层渐渐风化。
• The plane would probably disintegrate at that high speed.飞机以那么高速飞行也许会四分五裂。

14 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。

15 stainless   

adj.无瑕疵的，不锈的

参考例句：

• I have a set of stainless knives and forks.我有一套不锈钢刀叉。
• Before the recent political scandal,her reputation had been stainless.在最近的政治丑闻之前，她的名声是无懈可击的。

16 rims   

n.（圆形物体的）边( rim的名词复数 )；缘；轮辋；轮圈

参考例句：

• As she spoke, the rims of her eyes reddened a little. 说时，眼圈微红。 来自汉英文学 - 围城
• Her eyes were a little hollow, and reddish about the rims. 她的眼睛微微凹陷，眼眶有些发红。 来自辞典例句

17 toxic   

adj.有毒的，因中毒引起的

参考例句：

• The factory had accidentally released a quantity of toxic waste into the sea.这家工厂意外泄漏大量有毒废物到海中。
• There is a risk that toxic chemicals might be blasted into the atmosphere.爆炸后有毒化学物质可能会进入大气层。