VOA慢速英语--旅行者2号发现星际空间新奥妙

NASA’s Voyager 2 Discovers New Details About Interstellar Space

About one year ago, the U.S. space agency NASA's Voyager 2 spacecraft left our solar system. Several reports recently released in Nature Astronomy describe the spacecraft's main scientific findings.

NASA says Voyager 2's mission led to new discoveries about the border that divides our solar system from interstellar space. "Interstellar" means "between stars." But scientists define interstellar space as the place where the sun's continual flow of material and magnetic field stop affecting its surroundings.

Interstellar space is estimated to be about 18 billion kilometers from Earth.

What did the spacecraft find?

Project researchers say Voyager 2's scientific instruments discovered unexpected differences in the density¹ of plasma², a collection of charged particles existing in the solar system.

NASA also says the new research reports confirmed that both Voyager 1 and Voyager 2 appear to be in a transitional area just beyond the heliosphere. The heliosphere is a protective bubble that protects our solar system. It is created by solar wind formed from charged particles. The border of the solar system - the place where solar wind ends and interstellar space begins - is called the heliopause.

The team reported that data from Voyager 2 suggests that the heliopause appears to be much thinner than expected.

Edward Stone is a physicist³ with the California Institute of Technology and a project leader for the Voyager program. Stone told reporters the findings represent "a very exciting time for us."

He said in a statement the Voyager 2 mission was providing details about how the sun interacts with the materials that fill most of the space between stars in the Milky⁴ Way galaxy⁵.

Researchers said Voyager 2 also confirmed the existence of a "magnetic barrier" at the outer edge of the heliosphere that had been predicted by theory and observed by Voyager 1.

"Without this new data from Voyager 2, we wouldn't know if what we were seeing with Voyager 1 was characteristic of the entire heliosphere, or specific just to the location and time when it crossed," Stone said.

Leonard Burlaga is a scientist at NASA's Goddard Space Flight Center and a lead researcher on one of the reports. He told the French news agency AFP there were some surprises. "Contrary to all expectations and predictions, the magnetic field direction did not change when Voyager 2 crossed the heliopause," he said.

The spacecraft also collected information on incoming cosmic rays - particles that hit Earth from anywhere beyond its atmosphere. The data showed that the rays grew stronger as the Voyager explorers neared the heliopause.

Origins of the Voyager spacecraft

Voyager 2 was one of two explorers launched by NASA back in the summer of 1977. The other was Voyager 1. Both spacecraft were first designed to carry out fly-by studies of Jupiter and Saturn⁶.

Later, Voyager 2 completed the first-ever close observations of Uranus⁷ and Neptune⁸. The fly-by trips involving the four planets became known as the Voyager "Grand Tour."

The two spacecraft then began a new mission to explore areas at the edge of the sun's influence.

The two Voyagers – first built to last only five years – have long outlasted¹⁰ their operational lifetimes. But after 42 years in action, both are expected to run out of power and go silent within five years.

However, that does not mean that they will disappear. Bill Kurth, a researcher at the University of Iowa and co-writer of one of the research reports, said he expects the space explorers to outlast⁹ Earth. "They are in their own orbits around the galaxy for five billion years or longer," he said. "And the probability of them running into anything is almost zero."

Words in This Story

mission – n. an important task, usually involving travel

bubble – n. an enclosed or isolated¹¹ space

transitional – adj. changing from one system or method to another

characteristic – adj. typical of someone or something

specific – adj. a particular thing and not something general

contrary – adj. opposite or very different

1 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。

2 plasma   

n.血浆，细胞质，乳清

参考例句：

• Keep some blood plasma back for the serious cases.留一些血浆给重病号。
• The plasma is the liquid portion of blood that is free of cells .血浆是血液的液体部分，不包含各种细胞。

3 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。

4 milky   

adj.牛奶的，多奶的；乳白色的

参考例句：

• Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
• I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。

5 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。

6 Saturn   

n.农神，土星

参考例句：

• Astronomers used to ask why only Saturn has rings.天文学家们过去一直感到奇怪，为什么只有土星有光环。
• These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。

7 Uranus   

n.天王星

参考例句：

• Uranus is unusual because it is tilted.天王星非常特殊，因为它是倾斜的。
• Uranus represents sudden change and rebellion.天王星代表突然性的改变和反叛。

8 Neptune   

n.海王星

参考例句：

• Neptune is the furthest planet from the sun.海王星是离太阳最远的行星。
• Neptune turned out to be a dynamic,stormy world.海王星原来是个有生气、多风暴的世界。

9 outlast   

v.较…耐久

参考例句：

• The great use of life is to spend it doing something that will outlast it.人生的充分利用就是为争取比人生更长久的东西而度过一生。
• These naturally dried flowers will outlast a bouquet of fresh blooms.这些自然风干的花会比一束鲜花更加持久。

10 outlasted   

v.比…长久，比…活得长( outlast的过去式和过去分词 )

参考例句：

• I outlasted several downsizings but the last one included me. 虽然我坚持到了最后，还是逃不过被裁的命运。 来自互联网
• This clock has outlasted several owners. 这座时钟的寿命比它的几个主人的寿命都长。 来自互联网

11 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。