VOA慢速英语2011--NASA’s Aquarius Satellite Will Help Sc

EXPLORATIONS - NASA’s Aquarius Satellite Will Help Scientists Learn About Salt Levels in the Sea

STEVE EMBER: I’m Steve Ember.
DOUG JOHNSON: And I’m Doug Johnson with EXPLORATIONS in VOA Special English. Today we tell about an American space agency project to study salt levels in the Earth’s oceans. We report on plans to collect rock particles from a nearby asteroid¹. And we tell about a discovery of huge magnetic bubbles in space.
(MUSIC)
STEVE EMBER: On June tenth, the National Aeronautics² and Space Administration, NASA, launched a satellite called Aquarius. The satellite will measure and study the saltiness of Earth’s oceans from space. The aim of the project is to learn about our changing climate. The project is a joint³ effort between NASA and Argentina’s space agency.
Some satellites orbiting the Earth provide information about sea temperatures and depths. Others gather information about the ocean’s color and winds. But there has never before been a worldwide study of the salt levels of the sea surface.
Until now, this kind of information came only from ships and buoys⁴ floating in the ocean. Experts say Aquarius will gather as much information about sea surface salinity⁵ as has been collected by ships over the past one hundred twenty-five years.
DOUG JOHNSON: NASA officials say the project will give scientists a better understanding of Earth’s changing climate. They say it should provide missing information about the water cycle and the circulation, or movement, of ocean waters. These two forces are a major influence on the ocean’s climate. Experts say the salt measurements will provide the information that links these forces within the climate system.
The Earth’s water cycle is the continuous movement of water as it changes from a liquid to a vapor⁶ or gas. Water from the sea rises up as vapor to form clouds before changing to rain or snow. Most of the planet’s evaporation⁷ and precipitation take place over oceans. Understanding salt levels will help experts better understand how increases and decreases of fresh water from rain affect the ocean environment.
STEVE EMBER: When scientists study the circulation of ocean water, they are looking at how the water mass of the ocean forms layers and mixes together. This mixing is a product of the oceans’ density⁸ and buoyancy. These, in turn, depend on the water’s temperature and saltiness. Buoyancy is the upward force that a liquid places on an object that is less dense⁹ than itself. Knowing about salt levels helps tell scientists more about the ocean water movement.
Scientists will use salt water measurements to understand how the ocean’s climate is changing. Gary Lagerloef works for the Earth and Space Research Institute in Seattle, Washington. He is the main investigator¹⁰ of the Aquarius project. He says information gathered by Aquarius will show how the ocean environment is changing.
GARY LAGERLOEF: “One of the big overarching questions in climate is, is the global water cycle changing? Many climate forecasting models suggest that it will change over time as the climate warms up. But measuring these changes in rainfall over the ocean is very, very difficult to do. But salinity is actually an important parameter¹¹ that gives us an indication of what might be going on.”
DOUG JOHNSON: Aquarius will also produce maps of saltwater movement around the world every month. The satellite is equipped with microwave radiometers. These measuring devices must be very exact and secure to provide detailed¹² information.
Yi Chao is a scientist with the Aquarius project at NASA’s Jet Propulsion Lab in California. He says different intensities¹³ of saltwater produce different energy. The radiometer measures microwaves from the water. Scientists use mathematic equations to estimate salt levels based on those microwaves.
The Aquarius project is expected to last three years.
(MUSIC)
STEVE EMBER: NASA officials have announced plans to launch a spacecraft to a nearby asteroid in twenty sixteen. Asteroids¹⁴ are the rocky remains¹⁵ from the collapse¹⁶ of a solar nebula¹⁷. This huge cloud of gas collapsed¹⁸ about four billion five hundred million years ago to form our sun and planets.
The goal of the project is to collect rock particles from an asteroid called 1999 RQ36. Scientists hope to study these particles to learn more about how our solar system was formed. NASA says they might also provide a better understanding of how life began.
DOUG JOHNSON: The operation is called OSIRIS-REx. That is short for Origins-Spectral Interpretation-Resource Identification-Security–Regolith Explorer. It will take OSIRIS-Rex four years to travel to the asteroid. Once they are close together, the unmanned spacecraft will spend months mapping 1999RQ36. Experts will then choose an area of the asteroid where the spacecraft will take a rock sample using its robotic arm.
NASA already has a collection of meteorites¹⁹, small pieces of asteroids that broke away and fell to Earth. Organic molecules²⁰ on meteorites may hold valuable information. But the intense heat of passing through the Earth’s atmosphere likely damaged those molecules. After they land, meteorites can pick up small organisms and chemicals from Earth’s environment.
DOUG JOHNSON: Material from the RQ36 asteroid will be sent back to Earth in a special protective device. This way, it will be unchanged when it arrives on our planet in twenty-twenty-three.
STEVE EMBER: Gathering²¹ material from the asteroid is not the only goal. Experts have identified RQ36 as a possibly dangerous asteroid. There is a small chance it might hit the Earth in the year twenty-one eighty-two.
Experts say the OSIRIS-REx operation will help them learn more about asteroids by measuring the “Yarkovsky effect” for the first time. The “Yarkovsky effect” is a small push on an asteroid that happens when it takes in sunlight and produces heat. This small push adds up over time. Knowing more about how the Yarkovsky effect changes an asteroid’s orbit will help scientists better predict whether RQ36 will come near Earth.
DOUG JOHNSON: Michael Drake is the Director of the Lunar and Planetary Laboratory at the University of Arizona. His group will lead the OSIRIS-REx team. He says engineers are already studying ways to move the asteroid out of Earth’s path. One possible method is to create a large sail.
MICHAEL DRAKE: “There are strategies such as putting a large Mylar sail, maybe say half a mile across, attached to the surface, that in itself is an interesting engineering challenge, and using photons from the Sun to sail it away much like a sailboat works on the ocean.”
DOUG JOHNSON: Professor Drake says another way to move the asteroid would be to paint one side of the dark rock white. This would change the amount of sunlight it reflects. Changing the amount of solar photon pressure on the asteroid would change its path.
(MUSIC)
STEVE EMBER: NASA scientists say the agency’s two Voyager spacecraft have provided some surprising news about the edge of the solar system. They say this area seems to be made of huge bubble-like structures.
The two Voyager spacecraft were launched in nineteen seventy-seven. The two spacecraft have spent more than a third of a century traveling to the edges of our solar system. They are currently about fourteen billion kilometers from Earth.
Scientists say computer estimates suggest the bubbles are about one hundred sixty million kilometers wide. They say it would take one of the Voyagers weeks to cross just one bubble. Voyager One entered this area around two thousand seven. Voyager Two entered it about a year later. Scientists at first did not understand what the Voyagers were sensing, but now they believe they have a better idea.
DOUG JOHNSON: Merav Opher is an astronomer²² at Boston University. He explains that the sun’s magnetic field extends all the way to the edge of the solar system. As the sun turns, its magnetic field twists and folds. As the lines of the magnetic force cross one another, they reorganize into magnetic bubbles.
Earlier theories predicted that the faraway magnetic folds of the sun were curved and folded back to rejoin the sun. But these bubbles seem to be disconnected from the sun’s magnetic field. NASA says the structure of the sun’s far away magnetic field is of huge importance because it tells how our solar system interacts with the rest of the galaxy²³.
Merav Opher says scientists are hoping to learn more about these bubble structures. She says this finding is just the beginning, and that he expects more surprises ahead.
(MUSIC)
STEVE EMBER: This program was written and produced by Dana Demange, with reporting by Jessica Berman. I’m Steve Ember.
DOUG JOHNSON: And I’m Doug Johnson. Join us again next week for EXPLORATIONS in VOA Special English.

1 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

2 aeronautics   

n.航空术，航空学

参考例句：

• National Aeronautics and Space undertakings have made great progress.国家的航空航天事业有了很大的发展。
• He devoted every spare moment to aeronautics.他把他所有多余的时间用在航空学上。

3 joint   

adj.联合的，共同的；n.关节，接合处；v.连接，贴合

参考例句：

• I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤，肩膀脫臼了。
• We wrote a letter in joint names.我们联名写了封信。

4 buoys   

n.浮标( buoy的名词复数 )；航标；救生圈；救生衣v.使浮起( buoy的第三人称单数 )；支持；为…设浮标；振奋…的精神

参考例句：

• The channel is marked by buoys. 航道有浮标表示。 来自《现代汉英综合大词典》
• Often they mark the path with buoys. 他们常常用浮标作为航道的标志。 来自辞典例句

5 salinity   

n.盐分；咸度；盐浓度；咸性

参考例句：

• In the sea water sampled the salinity is two parts per thousand.在取样的海水中，盐度为千分之二。
• In many sedimentary basins the salinity of the formation water increases with depth or compaction.在许多沉积盆地中，地层水的含盐量随深度或压实作用而增高。

6 vapor   

n.蒸汽，雾气

参考例句：

• The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
• This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。

7 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。

8 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

9 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

10 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。

11 parameter   

n.参数，参量

参考例句：

• It is the parameter of distribution.这就是分布参数。
• One parameter which always comes into play is the national economy.国民经济是一个经常起作用的参量。

12 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

13 intensities   

n.强烈( intensity的名词复数 )；（感情的）强烈程度；强度；烈度

参考例句：

• At very high intensities, nuclear radiations cause itching and tingling of the skin. 当核辐射强度很高时，它能使皮肤感到发痒和刺痛。 来自辞典例句
• They ask again and again in a variety of ways and intensities. 他们会以不同的方式和强度来不停地问，直到他得到自己想要的答案为止。 来自互联网

14 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

15 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

16 collapse   

vi.累倒；昏倒；倒塌；塌陷

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。

17 nebula   

n.星云，喷雾剂

参考例句：

• A powerful telescope can resolve a nebula into stars.一架高性能的望远镜能从星云中分辨出星球来。
• A nebula is really a discrete mass of innumerous stars.一团星云实际上是无数星体不连续的集合体。

18 collapsed   

adj.倒塌的

参考例句：

• Jack collapsed in agony on the floor. 杰克十分痛苦地瘫倒在地板上。
• The roof collapsed under the weight of snow. 房顶在雪的重压下突然坍塌下来。

19 meteorites   

n.陨星( meteorite的名词复数 )

参考例句：

• Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
• One theory about the existence of extraterrestrial life rests on the presence of carbon compounds in meteorites. 地球外存在生命的理论是基于陨星上存在碳化合物质这一事实的。 来自《简明英汉词典》

20 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

21 gathering   

n.集会，聚会，聚集

参考例句：

• He called on Mr. White to speak at the gathering.他请怀特先生在集会上讲话。
• He is on the wing gathering material for his novels.他正忙于为他的小说收集资料。

22 astronomer   

n.天文学家

参考例句：

• A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
• He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。

23 galaxy   

n.星系；银河系；一群(杰出或著名的人物)

参考例句：

• The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
• The company has a galaxy of talent.该公司拥有一批优秀的人才。