VOA慢速英语2019--日本宇宙飞船返回家园

A Japanese spacecraft has left a distant asteroid¹ and started its return trip to Earth after successfully completing its mission.

The Japan Aerospace² Exploration Agency, known as JAXA, said the Hayabusa2 spacecraft left its orbit around the asteroid Ryugu, Wednesday. The space rock is currently about 300 million kilometers from Earth.

Hayabusa 2's mission was to gather soil samples and information that could provide clues to how the solar system formed, the country's space agency said. The spacecraft is to bring those samples back so scientists can study them in a laboratory.

Workers at the command center stood up and cheered when JAXA project manager Yuichi Tsuda confirmed the departure.

The spacecraft captured pictures of Ryugu as it began its return trip and sent them back to Earth. The asteroid Ryugu, or Dragon Palace, is named after a sea-bottom castle in a traditional Japanese story. Hayabusa2 will continue its "farewell filming" of the asteroid for a few more days, JAXA said.

As the spacecraft travels away from the asteroid and toward Earth it will adjust its position. It will retreat about 65 kilometers from the asteroid and out of its the gravitational pull. After that, the asteroid will be out of sight of the spacecraft.

"It's sad to say goodbye to Ryugu," Tsuda told reporters. "Literally³ it has been at the center of our lives over the past 1? years."

The spacecraft will then start its main thrusters in early December to power it back to Earth. The return trip will take about one year.

"We expect Hayabusa2 will bring us new scientific insights," Tsuda said. "Not only the data, but tangible⁴ samples will be in our hands."

Hayabusa2 arrived at the 900-meter-long asteroid in June 2018. The spacecraft touched down on the extremely rocky asteroid two times and successfully collected information and soil.

The first touchdown took place in February. Hayabusa2 collected surface dust samples at the time. In July, it collected samples from beneath the surface of the asteroid after landing in a shallow hole that it had blasted. The operation was the first of its kind in the history of space exploration.

Scientists said they detected small amounts of carbon and organic material in the asteroid soil samples. "They will allow us to explore how carbon, organic matter and water are scattered⁵ around in the solar system, why they exist on Ryugu, how they are related to the Earth," Tsuda said.

JAXA scientists believe the sub-surface samples contain valuable data because they are unaffected by space radiation and other forces. They believe the samples could tell more about the beginnings of the solar system 4.6 billion years ago.

Hayabusa2 is expected to reach Earth in late 2020 and drop a container holding the valuable samples in the Australian desert. Tsuda said landing the container at the targeted spot will require precision controls. Details are still being negotiated with the Australian government, he said.

After Hayabusa2 drops its container, the spacecraft may be used for another mission.

The spacecraft took more than three years to arrive at the asteroid. But the trip home is much shorter thanks to the current positions of Ryugu and Earth in their orbits.

Asteroids⁶ orbit the sun but are much smaller than planets or moons. They are believed to be among the oldest objects in the solar system and may help explain how Earth developed. They may even provide clues about the appearance of life.

Words in This Story

mission –n. a task or job that must be done

sample –n. a small amount of something that gives information about the object it is taken from

thruster –n. part of a rocket engine that directs force

tangible –adj. something that can be touched and felt

allow –v. to permit, to let happen

precision –adj. the quality of being very exact, very accurate

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 aerospace   

adj.航空的，宇宙航行的

参考例句：

• The world's entire aerospace industry is feeling the chill winds of recession.全世界的航空航天工业都感受到了经济衰退的寒意。
• Edward Murphy was an aerospace engineer for the US Army.爱德华·墨菲是一名美军的航宇工程师。

3 literally   

adv.照字面意义，逐字地；确实

参考例句：

• He translated the passage literally.他逐字逐句地翻译这段文字。
• Sometimes she would not sit down till she was literally faint.有时候，她不走到真正要昏厥了，决不肯坐下来。

4 tangible   

adj.有形的，可触摸的，确凿的，实际的

参考例句：

• The policy has not yet brought any tangible benefits.这项政策还没有带来任何实质性的好处。
• There is no tangible proof.没有确凿的证据。

5 scattered   

adj.分散的，稀疏的；散步的；疏疏落落的

参考例句：

• Gathering up his scattered papers,he pushed them into his case.他把散乱的文件收拾起来，塞进文件夹里。

6 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。