VOA科学技术2024--Study: NASA Space Strike Might Have Reshaped an Asteroid

Study: NASA Space Strike Might Have Reshaped an Asteroid¹

　　A new study suggests that an asteroid strike by an American spacecraft likely changed the shape of the targeted object.

　　NASA crashed the DART² spacecraft into the asteroid Dimorphos in 2022. The asteroid strike happened about 11 million kilometers from Earth.

　　The experiment tested a method for changing the orbit of some asteroids³ to prevent them from possibly crashing into our planet in the future.

　　NASA has said its studies of the crash showed it was successful because the force of the strike changed the asteroid's orbit around a larger asteroid Didymos. NASA's measurements also found the strike reduced the orbital period of Dimorphos by 33 minutes.

　　Such a major crash would normally create a large crater⁴ in the targeted object. But a new study presents evidence that the crash made more than a hole – it likely changed the shape of the whole asteroid.

　　Astronomers⁵ at the University of Bern, in Switzerland carried out the research. A study detailing the findings recently appeared in the publication Nature Astronomy.

　　The team used a computer simulation system to study the changes to Dimorphos that resulted from the crash. The system aimed to recreate the breakup of space objects that have been hit.

　　The researchers said their simulation method has been used in the past to recreate space objects crashing into each other. For example, the team said it confirmed the results of a Japanese spacecraft collecting a sample from the Ryugu asteroid in 2019.

　　Sabina Raducan is with the Physics Institute of the University of Bern. She helped lead the project. Raducan described the simulation process in a statement as "computationally intensive." In total, she said 250 simulations were completed, which reproduced the first two hours after the asteroid strike.

　　The researchers used all available information about NASA's operation. These included the predicted shape of Dimorphos, data on the strike itself, as well as the size of the cloud the crash left behind. In addition, the team aimed to estimate unknown details about the asteroid and the surrounding area.

　　"Then what we did is check which of the simulation run outcomes most closely match observed reality," Raducan said.

　　She added that results of the research provided clear evidence that the crash turned Dimorphos into a relatively⁶ weak "rubble⁷ pile" asteroid. Raducan explained this meant that the object is currently being held together "by the asteroid's extremely weak gravity" rather than a solid and strong mass.

　　The researchers noted⁸ that the results of the simulation and the team's examinations partly explain why the crash was so effective in changing the path of the asteroid.

　　Raducan said the results also persuaded the team that "the likelihood is that the crater grew to encompass⁹ the entire body itself, so that Dimorphos ended up being completely reshaped." It is therefore unlikely that a crater still exists after the crash.

　　The researchers said the existence of a crater can be investigated further by a European Space Agency (ESA) spacecraft. The spacecraft, called Hera, is preparing for a possible launch in October.

　　ESA says Hera's cameras and instruments will carry out detailed¹⁰ studies of Dimorphos and the asteroid it orbits, Didymos. During the operation, the spacecraft will aim to collect the most data yet on such an asteroid system.

　　Words in This Story

　　asteroid – n. a rocky object that goes around the sun like a planet

　　crater – n. a big hole left in the ground or an object by a force of impact

　　simulate – v. to do or make something that behaves or looks like something real but is not

　　check –v. to look for something of interest or something that might be a mistake

　　rubble – n. pieces of broken bricks from a destroyed structure

　　pile – n. an amount of substance in the shape of a small hill or a number of objects laying on top of each other

　　encompass – v. to include a lot of things

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 dart   

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   

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 crater   

n.火山口，弹坑

参考例句：

• With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
• They came to the lip of a dead crater.他们来到了一个死火山口。

5 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• 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。 来自《简明英汉词典》

6 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

7 rubble   

n.（一堆）碎石，瓦砾

参考例句：

• After the earthquake,it took months to clean up the rubble.地震后，花了数月才清理完瓦砾。
• After the war many cities were full of rubble.战后许多城市到处可见颓垣残壁。

8 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

9 encompass   

vt.围绕，包围；包含，包括；完成

参考例句：

• The course will encompass physics,chemistry and biology.课程将包括物理、化学和生物学。
• The project will encompass rural and underdeveloped areas in China.这项工程将覆盖中国的农村和不发达地区。

10 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。