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We’ve left trash in space, where it can be a danger to satellites and astronauts. Already, over 500,000 pieces of space trash orbit Earth. They come from old satellites and other objects humans have sent into space. Each travels at over 28,000 kilometers per hour. At speeds like that, even tiny flecks(微粒) of dust can harm spacecraft — and any passengers.

Growing up near Kennedy Space Center in Florida, Amber Yang, the 17-year-old senior at Trinity Preparatory School in Winter Park, Fla, has always been interested in space. But she didn’t think about space junk until 2013, during which debris from an old satellite collided with an active Russian satellite. The space trash slammed into the satellite, knocking it off course and out of commission.

So Amber decided to come up with her own method — one that could use the knowledge of where space junk has been to more accurately predict where it would go next. She used her computer to create an artificial neural(神经系统的) network, for which she started with a set of rules called Kepler’s laws of planetary motion. Amber’s computer program applied Kepler’s laws to data on the locations of space trash. She hoped her artificial neural network could use those data to figure out where that junk could go next. If those predictions turned out to be wrong, her program could learn from those mistakes to do better in the future.

“When I first started out with my research,” Amber says, “I had a hard time finding data for space debris.” So she randomly generated her own data. The next year, though, Amber discovered space-track.org, which provides a free record of space debris.

She downloaded data on the locations of space debris from May 25 to June 9 , 2016. She then asked her program to use those data to predict where the trash would be on June 12. She compared her program’s answer to the actual locations of the space trash. “I had 98 percent accuracy,” she says.

1.What makes space debris a threat to satellites and astronauts?

A Its large amount.

B Its good flexibility.

C Its travelling speed.

D Its being out of control.

解析：选C。细节理解题。根据第一段Each travels at over 28,000 kilometers per hour. At speeds like that, even tiny flecks of dust can harm spacecraft — and any passengers.可知太空垃圾的危险性来自于它们的高速运动，故选C项。

2.Which can best replace the underlined phrase in Paragraph 2?

A Broke down.

B Crashed into.

C Came across.

D Brought about.

解析：选B。B 词义猜测题。该短语所在句子“... Debris from an old satellite collided with an active Russian satellite...”描述的是碎片与运行的卫星发生的动作，又根据后一句“太空垃圾猛烈撞击了卫星，使其偏离了轨道无法运行”，推断collided with表示两者“碰撞”，故选B。

3.What can we conclude about Amber’s computer progam?

A It will reduce the release of space trash.

B It works effectively without making errors.

C It predicts where the satellite debris will go.

D It takes an advantage of Kepler’s laws.

解析：选D。D 细节理解题。根据第三段的“...she started with a set of rules called Kepler’s laws of planetary motion.”可知她的电脑程序利用了开普勒定律，故选D。

4.What made Amber increase the accuracy of her testing program?

A The data generated by herself.

B The data provided on a website.

C The results of previous research.

D The predictions made by others.

解析：选B。细节理解题。根据第四段So she randomly generated her own data. The next year, though, Amber discovered space-track.org, which provides a free record of space debris. 和第五段第一句可推断是使用了一个网站上的数据提供了她实验的准确性，故选B项。

5.What is the purpose of writing the passage?

A To warn people of dangers of space debris.

B To introduce a way to predict space trash.

C To report a teenager’s computer program.

D To show a breakthrough in space exploration.

解析：选C。C 写作意图题。本文主要介绍一位十七岁的美国女孩所开发了一款能预测太空垃圾去向的计算机程序，故选C项。