2007年VOA标准英语-NASA Mission to Seek Polar Lights' Energy Sourc

By David McAlary
Washington
18 February 2007

The U.S. space agency NASA has launched five satellites - the most ever from one rocket - to locate the source of energy in Earth's magnetic field that triggers the colorful, dancing auroras over the north and south poles. As we hear from VOA's David McAlary, a finding would help scientists better understand how gigantic storms on the sun that supply this energy disrupt electrical systems on Earth and in spacecraft.

Delta1 II rocket with NASA's THEMIS spacecraft aboard lifts off" hspace="2" src="/upimg/allimg/070522/0813280.jpg" width="193" vspace="2" border="0" />

The Delta II rocket with NASA's THEMIS spacecraft aboard lifts off

The so-called northern and southern lights glow and shimmer² colorfully in what 19th century Scottish poet W.E. Aytoun described as streamers shooting all night long across the trembling sky.

Despite their visual appeal, these brilliant light shows are storms - geomagnetic storms. Scientists call them substorms, a part of larger storms of energy propelled from the sun at supersonic speeds toward Earth and elsewhere in the solar system.

This energy involves tons of charged particles, hurled³ our way in the so-called solar wind. Earth's magnetic field repels⁴ most of this onslaught, but some occasionally leaks through as a result of a sudden, explosive release of these particles from the solar wind.

The outcome is the light shows over the poles and sometimes the undesirable⁵ disruption of electrical power systems and telecommunications on Earth and spacecraft in orbit.

Solar physicist⁶ Vassilis Angelopoulos of the University of California at Berkeley says the precise point in Earth's magnetic field where this explosive particle release occurs and the sequence of events leading to it have puzzled scientists for three decades. "Knowing the trigger location identifies the correct physics at play. The problem has been that the substorms start at a single point in space, somewhere near Earth, and, within minutes, it progresses past the moon's orbit, so a single satellite alone cannot identify the substorm time and point of origin," he said.

To seek the answer to this mystery, NASA has launched five satellites aboard a Delta rocket from Florida to train their instruments on the northern and southern lights. The project is called THEMIS.

Once in orbit, two of the THEMIS spacecraft will circle Earth about one-sixth the distance to the moon while the other two circle half way to the moon. A fifth will be a reserve, if one of the others fails during the two-year mission.

Angelopoulos says a finding will help scientists know more about the threatening solar storms and how our planet's magnetic field works. "Understanding and predicting space storms is important for protecting our satellites and astronauts in space. Meteorologists study tornadoes⁷ to understand the most severe thunderstorms, and we, too, want to study substorms to gain insight into the most intense space storms," he said.

Cramming⁸ five miniature satellites into the nose of one launch rocket has had a collateral⁹ engineering benefit. Each is a cube, less than one meter wide and high. The THEMIS project manager at the University of California, Peter Harvey, says it has taught technicians how to make small satellites with little computers and other instruments. "It has been a challenging project to pack so much into five small spacecraft. We learned a lot about how to build a constellation¹⁰ of spacecraft. We look forward to some terrific scientific discoveries," he said.

1 delta   

n.（流的）角洲

参考例句：

• He has been to the delta of the Nile.他曾去过尼罗河三角洲。
• The Nile divides at its mouth and forms a delta.尼罗河在河口分岔，形成了一个三角洲。

2 shimmer   

v./n.发微光，发闪光；微光

参考例句：

• The room was dark,but there was a shimmer of moonlight at the window.屋子里很黑，但靠近窗户的地方有点微光。
• Nor is there anything more virginal than the shimmer of young foliage.没有什么比新叶的微光更纯洁无瑕了。

3 hurled   

v.猛投，用力掷( hurl的过去式和过去分词 )；大声叫骂

参考例句：

• He hurled a brick through the window. 他往窗户里扔了块砖。
• The strong wind hurled down bits of the roof. 大风把屋顶的瓦片刮了下来。 来自《简明英汉词典》

4 repels   

v.击退( repel的第三人称单数 )；使厌恶；排斥；推开

参考例句：

• His manner repels me. 他的举止让我厌恶。 来自《简明英汉词典》
• Her callous attitude repels me. 她冷酷无情的态度引起我的反感。 来自《简明英汉词典》

5 undesirable   

adj.不受欢迎的，不良的，不合意的，讨厌的；n.不受欢迎的人，不良分子

参考例句：

• They are the undesirable elements among the employees.他们是雇员中的不良分子。
• Certain chemicals can induce undesirable changes in the nervous system.有些化学物质能在神经系统中引起不良变化。

6 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

7 tornadoes   

n.龙卷风，旋风( tornado的名词复数 )

参考例句：

• Tornadoes, severe earthquakes, and plagues create wide spread havoc. 龙卷风、大地震和瘟疫成普遍的毁坏。 来自互联网
• Meteorologists are at odds over the working of tornadoes. 气象学者对龙卷风的运动方式看法不一。 来自互联网

8 cramming   

n.塞满，填鸭式的用功v.塞入( cram的现在分词 )；填塞；塞满；（为考试而）死记硬背功课

参考例句：

• Being hungry for the whole morning, I couldn't help cramming myself. 我饿了一上午，禁不住狼吞虎咽了起来。 来自《简明英汉词典》
• She's cramming for her history exam. 她考历史之前临时抱佛脚。 来自《简明英汉词典》

9 collateral   

adj.平行的；旁系的；n.担保品

参考例句：

• Many people use personal assets as collateral for small business loans.很多人把个人财产用作小额商业贷款的抵押品。
• Most people here cannot borrow from banks because they lack collateral.由于拿不出东西作为抵押，这里大部分人无法从银行贷款。

10 constellation   

n.星座n.灿烂的一群

参考例句：

• A constellation is a pattern of stars as seen from the earth. 一个星座只是从地球上看到的某些恒星的一种样子。
• The Big Dipper is not by itself a constellation. 北斗七星本身不是一个星座。