New Studies Show NASA’s Asteroid Crash Test Was Highly Successful

Several new studies confirm the success of a test by the American space agency NASA to crash a spacecraft into an asteroid¹.

The studies suggest the experiment was an important first step in learning how spacecraft might be able to protect Earth from asteroids² or other space objects that might threaten the planet.

NASA carried out the operation last September with the DART³ spacecraft. It crashed into an asteroid called Dimorphos, a small "moonlet" that orbits a larger asteroid, Didymos. The crash happened about 11 million kilometers from Earth.

NASA reported in October that it considered the test a success because the force of the crash changed the path of the asteroid. Now, several new studies are confirming the effectiveness of the experiment.

A team from the Johns Hopkins Applied⁴ Physics Laboratory in Laurel, Maryland examined data about the mission that NASA describes as the world's first planetary defense⁵ test. But the asteroid targeted in the mission never presented a threat to Earth.

Satellites and powerful telescopes observed DART's crash into the asteroid. The goal of the crash was to see how it might redirect the asteroid's path and speed.

Before the hit, Dimorphos was completing one orbit around Didymos every 11 hours and 55 minutes. The latest results showed the crash reduced this orbital period by 33 minutes. This is one minute more than NASA first announced after examining data from the crash in October.

"The DART test was phenomenally successful," said planetary scientist Terik Daly of the Johns Hopkins University Applied Physics Laboratory. He added that the experiment proved the impact method could be used to prevent an asteroid from crashing into Earth "if one day we had the need to."

The studies, which recently appeared in the publication Nature, examined many different elements involved in the crash experiment. These included a major study of the impact itself and looking closely at crash timelines and investigating how the targeted asteroid changed size and shape.

The researchers said one of the most important findings was that the asteroid's travel path was not just affected⁶ by being struck by the DART spacecraft. The space object's speed and direction were also greatly influenced by materials released by the asteroid after impact.

The researchers said the impact by the DART spacecraft led to a recoiling⁷ effect of the asteroid. When something recoils⁸, it moves suddenly in reaction to a force. A large amount of material from the asteroid was observed after impact, the team reported.

This recoiling effect – caused by materials being released into space after the crash – gave the object additional momentum⁹, the team reported. The researchers reported the impact caused an immediate¹⁰ slowing in the targeted asteroid's speed. The additional momentum Dimorphos picked up from the release of materials was far greater than the spacecraft impact itself, they added.

The researchers noted¹¹ the experiment showed that such operations can be carried out on asteroids that have not been studied in-depth before. What is required, however, is enough warning time to prepare for a specific mission. The team said that ideally, scientists will need several years of lead time to study any asteroids identified as a threat to Earth.

The scientists noted DART's impact had turned Dimorphos into an "active asteroid." An active asteroid is one that orbits like other asteroids, but has a trail of material following it, like a comet.

Some scientists had in the past proposed the idea that some active asteroids are the result of impact events. But until the DART experiment, no one had observed an actual activation¹².

Daly, of the Applied Physics Laboratory, said no known asteroids currently present a threat to Earth. But he added that the latest studies support the need for more research to prepare for such a possibility. Daly made a comparison to testing a car's airbags. "You make sure they work during a crash test instead of waiting to get in a real car accident to find out if they work," he said.

Words in This Story

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

mission – n. a flight by an aircraft or spacecraft to perform a specific task

phenomenal – adj. extremely successful or showing great qualities or abilities

momentum – n. the way in which something continues to move, increase or develop

trail – n. a line of marks that someone or something leaves behind as they move

comet – n. an object in space that leaves a bright line behind it in the sky

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 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。

3 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。

4 applied   

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 defense   

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。

6 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

7 recoiling   

v.畏缩( recoil的现在分词 )；退缩；报应；返回

参考例句：

• Some of the energy intended for the photon is drained off by the recoiling atom. 原来给予光子的能量有一部分为反冲原子所消耗。 来自辞典例句
• A second method watches for another effect of the recoiling nucleus: ionization. 探测器使用的第二种方法，是观察反冲原子核的另一种效应：游离。 来自互联网

8 recoils   

n.（尤指枪炮的）反冲，后坐力( recoil的名词复数 )v.畏缩( recoil的第三人称单数 )；退缩；报应；返回

参考例句：

• A gun recoils after being fired. 枪在射击后向后坐。 来自《现代英汉综合大词典》
• A molecule striking an advancing piston recoils with increased speed. 撞在前进中的活塞上的分子，会加速反跳。 来自辞典例句

9 momentum   

n.动力，冲力，势头；动量

参考例句：

• We exploit the energy and momentum conservation laws in this way.我们就是这样利用能量和动量守恒定律的。
• The law of momentum conservation could supplant Newton's third law.动量守恒定律可以取代牛顿第三定律。

10 immediate   

adj.立即的；直接的，最接近的；紧靠的

参考例句：

• His immediate neighbours felt it their duty to call.他的近邻认为他们有责任去拜访。
• We declared ourselves for the immediate convocation of the meeting.我们主张立即召开这个会议。

11 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。

12 activation   

n. 激活，催化作用

参考例句：

• A computer controls the activation of an air bag.电脑控制着气囊的启动。