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VOA科学技术2022--NASA Strikes an Asteroid to Change Its Direction

时间:2022-10-09 05:33:07

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NASA Strikes an Asteroid1 to Change Its Direction

A spacecraft from the American space agency NASA crashed into an asteroid about 11 million kilometers from Earth on Monday.

The mission is part of NASA's Double Asteroid Redirection Test, or DART2. The agency called it "the world's first mission to test technology for defending Earth" against asteroids3 or other space dangers.

The spacecraft traveled at a speed of 22,500 kph. It hit the asteroid Dimorphos on Monday.

NASA watched the event live from the mission operation center in Maryland with cameras and telescopes on Earth. It hopes that the crash will re-direct the asteroid's path. But it will be some time before the agency knows if it changed the asteroid's orbit.

Asteroid target

Nancy Chabot is the mission team leader at Johns Hopkins University's Applied4 Physics Laboratory, which oversees5 the effort. She said before the impact that "This isn't going to blow up the asteroid." Rather, she said, "This really is about asteroid deflection, not disruption."

The target, Dimorphos, is about 160 meters wide. It completes one orbit around a parent asteroid called Didymos every 11 hours and 55 minutes. NASA engineers are hoping that the crash would shorten the time it takes for the smaller asteroid to orbit the larger one by several minutes. They note that even 73 seconds would be considered a success.

Although the impact only changes the asteroid's orbit slightly, that will add up to a major re-direction over time, Chabot said. "So if you were going to do this for planetary defense6, you would do it five, 10, 15, 20 years in advance in order for this technique to work."

The two asteroids are not a threat to Earth. But the test shows whether crashing a spacecraft into an asteroid is an effective way to change its course, should an Earth-threatening asteroid be discovered in the future.

Dimorphos and Didymos are both very small compared to the Chicxulub asteroid that was estimated to strike Earth some 66 million years ago. The impact destroyed most of the world's plants and animals including dinosaurs7.

Dimorphos is among the 27,500 asteroids of all sizes under NASA observation. Many more have not been found as of October 2021. The space agency says that there is no known asteroid larger than 140 meters in size that has a chance to hit Earth in the next 100 years.

DART

The DART spacecraft has one instrument: a camera used for navigating8 and recording9 images until the time of impact and self-destruction.

DART is 1.3 meters long and weighs 570 kilograms. The vehicle is like a battering11 ram10, a heavy object that is used to break through a door or wall, aiming for the 5-billion-kilogram asteroid. "Sometimes we describe it as running a golf cart into a Great Pyramid," said Chabot.

DART is the latest of several NASA missions in recent years to explore and interact with asteroids. Last year, NASA launched a spaceship on a trip to the Trojan asteroid group orbiting near Jupiter. And the spacecraft OSIRIS-REx is returning to Earth with rocks collected in October 2020 from the asteroid Bennu.

Other countries, including China and Japan, have also launched their own asteroid missions.

Words in This Story

asteroid –n. one of many thousands of small rocks orbiting the sun

deflection –n. the act of causing something to change direction

disruption –n. the act of causing something to be unable to continue in a normal way

in advance –adv. ahead of time; before something happens

impact –n. the event of one thing striking another


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1 asteroid uo1yD     
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 dart oydxK     
v.猛冲,投掷;n.飞镖,猛冲
参考例句:
  • The child made a sudden dart across the road.那小孩突然冲过马路。
  • Markov died after being struck by a poison dart.马尔科夫身中毒镖而亡。
3 asteroids d02ebba086eb60b6155b94e12649ff84     
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。
4 applied Tz2zXA     
adj.应用的;v.应用,适用
参考例句:
  • She plans to take a course in applied linguistics.她打算学习应用语言学课程。
  • This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。
5 oversees 4607550c43b2b83434e5e72ac137def4     
v.监督,监视( oversee的第三人称单数 )
参考例句:
  • She oversees both the research and the manufacturing departments. 她既监督研究部门又监督生产部门。 来自《简明英汉词典》
  • The Department of Education oversees the federal programs dealing with education. 教育部监管处理教育的联邦程序。 来自互联网
6 defense AxbxB     
n.防御,保卫;[pl.]防务工事;辩护,答辩
参考例句:
  • The accused has the right to defense.被告人有权获得辩护。
  • The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。
7 dinosaurs 87f9c39b9e3f358174d58a584c2727b4     
n.恐龙( dinosaur的名词复数 );守旧落伍的人,过时落后的东西
参考例句:
  • The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
  • Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》
8 navigating 7b03ffaa93948a9ae00f8802b1000da5     
v.给(船舶、飞机等)引航,导航( navigate的现在分词 );(从海上、空中等)横越;横渡;飞跃
参考例句:
  • These can also be very useful when navigating time-based documents, such as video and audio. 它对于和时间有关的文档非常有用,比如视频和音频文档。 来自About Face 3交互设计精髓
  • Vehicles slowed to a crawl on city roads, navigating slushy snow. 汽车在市区路上行驶缓慢,穿越泥泞的雪地。 来自互联网
9 recording UktzJj     
n.录音,记录
参考例句:
  • How long will the recording of the song take?录下这首歌得花多少时间?
  • I want to play you a recording of the rehearsal.我想给你放一下彩排的录像。
10 ram dTVxg     
(random access memory)随机存取存储器
参考例句:
  • 512k RAM is recommended and 640k RAM is preferred.推荐配置为512K内存,640K内存则更佳。
11 battering 98a585e7458f82d8b56c9e9dfbde727d     
n.用坏,损坏v.连续猛击( batter的现在分词 )
参考例句:
  • The film took a battering from critics in the US. 该影片在美国遭遇到批评家的猛烈抨击。
  • He kept battering away at the door. 他接连不断地砸门。 来自《简明英汉词典》

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