A spacecraft from the American space agency NASA crashed into an asteroid about 11 million kilometers from Earth on Monday.
周一，美国宇航局的一艘航天器撞上了距离地球约1100万公里的一颗小行星。
The mission is part of NASA's Double Asteroid Redirection Test, or DART.
该任务是美国宇航局双小行星重定向测试(DART)的一部分。
The agency called it "the world's first mission to test technology for defending Earth" against asteroids or other space dangers.
宇航局称这是“世界上第一个测试保护地球免受小行星或其他太空危险的技术的任务”。
The spacecraft traveled at a speed of 22,500 kph.
航天器以每小时22，500公里的速度飞行。
It hit the asteroid Dimorphos on Monday.
它在周一撞上了小行星Dimorphos。
NASA watched the event live from the mission operation center in Maryland with cameras and telescopes on Earth.
美国宇航局在马里兰州的任务操作中心通过地球上的相机和望远镜现场观看了这一事件。
It hopes that the crash will re-direct the asteroid's path.
它希望这次撞击将改变小行星的轨道。
But it will be some time before the agency knows if it changed the asteroid's orbit.
但宇航局称还需要一段时间才能知道它是否改变了这颗小行星的轨道。
Nancy Chabot is the mission team leader at Johns Hopkins University's Applied Physics Laboratory, which oversees the effort.
南希·夏伯特是约翰霍普金斯大学应用物理实验室的任务小组负责人，该实验室负责监督这项工作。
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.
她在撞击前说：“这不会炸毁小行星。”相反，她说，“这实际上是关于小行星偏转，而不是破坏。”目标，Dimorphos，约160米宽。
It completes one orbit around a parent asteroid called Didymos every 11 hours and 55 minutes.
它每11小时55分钟绕双星系统中一颗名为Didymos的小行星运行一圈。
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.
美国宇航局的工程师们希望这次撞击能将较小的小行星绕较大的小行星运行的时间缩短几分钟。
They note that even 73 seconds would be considered a success.
他们指出，即使是73秒也被认为是成功的。
Although the impact only changes the asteroid's orbit slightly, that will add up to a major re-direction over time, Chabot said.
夏伯特说，虽然撞击只会轻微改变小行星的轨道，但随着时间的推移，这将导致重大的方向改变。
"So if you were going to do this for planetary defense, 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.
“所以，如果你要为行星防御做这件事，你需要提前5年、10年、15年、20年，才能让这项技术发挥作用。”这两颗小行星对地球不构成威胁。
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.
但该试验表明，如果未来发现威胁地球的小行星，将航天器撞向小行星是否是改变其轨道的有效方法。
Dimorphos and Didymos are both very small compared to the Chicxulub asteroid that was estimated to strike Earth some 66 million years ago.
Dimorphos和Didymos与据估计在6600万年前撞击地球的希克苏鲁伯小行星相比都非常小。
The impact destroyed most of the world's plants and animals including dinosaurs.
那次撞击摧毁了世界上大部分的动植物，包括恐龙。
Dimorphos is among the 27,500 asteroids of all sizes under NASA observation.
Dimorphos是美国宇航局观测到的27500颗大小不一的小行星之一。
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.
截至2021年10月，还有很多没有发现。美国宇航局表示，在未来100年里，目前已知的尺寸大于140米的小行星中没有一颗有机会撞击地球。
The DART spacecraft has one instrument: a camera used for navigating and recording images until the time of impact and self-destruction.
DART航天器有一个仪器：一个用于导航和记录图像的相机，直到撞击和自我毁灭。
DART is 1.3 meters long and weighs 570 kilograms.
DART长1。3米，重570公斤。
The vehicle is like a battering ram, a heavy object that is used to break through a door or wall, aiming for the 5-billion-kilogram asteroid.
该飞行器就像一个攻城锤，一个用来打破门或墙的重物，目标是50亿公斤重的小行星。
"Sometimes we describe it as running a golf cart into a Great Pyramid," said Chabot.
“有时我们把它描述为一辆高尔夫球车撞上金字塔，”夏伯特说。
DART is the latest of several NASA missions in recent years to explore and interact with asteroids.
DART是NASA近年来探索小行星并与之相互作用的几个任务中最新的一个。
Last year, NASA launched a spaceship on a trip to the Trojan asteroid group orbiting near Jupiter.
去年，美国宇航局发射了一艘宇宙飞船，前往木星附近的特洛伊小行星群。
And the spacecraft OSIRIS-REx is returning to Earth with rocks collected in October 2020 from the asteroid Bennu.
航天探测器OSIRIS-REx将带着2020年10月从小行星Bennu收集的岩石返回地球。
Other countries, including China and Japan, have also launched their own asteroid missions.
包括中国和日本在内的其他国家也已经开启了自己的小行星任务。
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