好英语网我们能避免“小行星撞地球”的毁灭性结局吗？
LAUREL, Md. — It’s the plot point for more than one Hollywood blockbuster: A rogue asteroid is hurtling toward Earth, threatening tsunamis, mass destruction and the death of every human being on the planet.
马里兰州劳雷尔市——这是好莱坞大片的常见情节了：一颗失控小行星冲向地球，可能造成海啸、大规模毁坏和全人类灭绝。
Humanity has one shot to save itself with brave, self-sacrificing heroes piloting a spacecraft into the cosmos to destroy the asteroid.
人类只有一次自救机会——勇敢、甘愿自我牺牲的英雄驾驶着宇宙飞船飞向太空，将小行星摧毁。
周一，美国宇航局的DART航天器与小行星“双卫一”撞击的11秒之前。
But that’s the movies. On Monday evening, NASA showed what the reality would be like.
但那只是电影。周一晚上，美国宇航局展示了这一情节变成现实会是怎样的场面。
There was an asteroid, but it wasn’t threatening the Earth. And there was a spacecraft, relying solely on sophisticated technology. The human heroes of the mission were actually at a physics and engineering lab between Baltimore and Washington, D.C.
确实是有一颗小行星，但它并未威胁到地球。还有一架完全依靠精密的技术运行的航天器。这一任务的人类英雄实际上是位于巴尔的摩和华盛顿之间的一处物理与工程实验室。
And there was a collision. In this case it was the final act of the Double Asteroid Redirection Test, or DART, a spacecraft that launched in November and then raced around the sun for 10 months as it pursued its target — a small space rock, Dimorphos, seven million miles from Earth.
碰撞也的确发生了。只不过这是双小行星改道测试(DART)的最终步骤，DART是去年11月发射的航天器，绕行太阳已有10个月，追逐着距离地球约1100万公里的一块名为“双卫一”的小型太空岩石。
“For the first time, humanity has demonstrated the ability to autonomously target and alter the orbit of a celestial object,” Ralph Semmel, director of the Johns Hopkins University Applied Physics Laboratory, said during a news conference after the crash. The laboratory managed the mission for NASA.
“人类首次展示了自主锚定和改变天体运行轨道的能力，”约翰斯·霍普金斯大学应用物理实验室主任拉尔夫·塞梅尔在撞击后的新闻发布会上表示。该实验室为美国宇航局执行这一项目。
Hitting an asteroid with a high-speed projectile nudges its orbit. For an asteroid headed toward Earth, that could be enough to change a direct hit to a near miss.
利用高速抛射体撞击小行星会轻微改变其运行轨道。对于一颗冲向地球的小行星来说，这已足够将直接撞击的结果改为差之毫厘。
In its last moments, the spacecraft sent back a series of photographs of the asteroid, Dimorphos, as it approached at more than 14,000 miles per hour.
在撞击发生前，航天器发回了一系列小行星“双卫一”的照片，当时它正以每小时超过22530公里的速度接近地球。
DART had spotted Dimorphos only about an hour earlier, as a dot of light. Then, the pile of celestial rubble grew bigger and bigger, until the picture of the asteroid’s surface strewn with boulders filled the screen. The mission’s engineers were on their feet, cheering.
DART仅提前一小时发现了“双卫一”，当时它还只是个光点。随后，这堆天体碎石体积越来越大，大到布满石块的小行星表面填满了其屏幕。该任务的工程师们都站了起来，开始欢呼。
“Normally, losing signal from the spacecraft is a very bad thing,” Dr. Semmel said. “But in this case, it was the ideal outcome.”
“通常情况下，航天器信号丢失是非常糟糕的事情，”塞梅尔博士说。“但这回是理想的结果。”
There was one more partial image, but the data never made it back to Earth. DART had smashed into the asteroid.
还有一张局部图片，但数据没能传回地球。DART已经撞上了小行星。
“Wow, that was amazing, wasn’t it?” said Nancy Chabot, a planetary scientist at the laboratory who works on the mission, during the NASA webcast.
“哇，那实在太棒了，不是吗？”在美国宇航局进行网页直播期间，该实验室参与了此项目的行星科学家南希·查博特说道。
With movies like “Armageddon,” “Deep Impact” and, more recently, “Don’t Look Up,” Hollywood has long been fascinated with the prospect of disaster raining down from the cosmos. In recent years, scientists and policymakers have also taken the threat more seriously than they once did.
《世界末日》(Armageddon)、《天地大冲撞》(Deep Impact)以及最近的《不要抬头》(Don’t Look Up,)这样的电影都说明了好莱坞一直以来对于灾难从天而降的可能性有多么着迷。近年，科学家和政策制定者也比以前更加重视这种威胁。
For many years, policymakers lacked urgency to finance efforts to protect the planet from asteroids. But that began to shift in part because astronomers have been able to find all of the big asteroids that would wreak planet-wide destruction, like the one that doomed the dinosaurs 66 million years ago, said Thomas Statler, the program scientist on the DART mission.
多年来，政策制定者一直不认为需要赶紧拨款用于保护地球免受小行星撞击。但该DART任务的项目科学家托马斯·斯塔特勒表示，这种情况开始发生转变，部分原因是天文学家已经能够找到所有会造成地球毁灭的大型小行星，就像6600万年前导致恐龙灭绝的那一颗。
Impacts of a global scale occur very rarely, once every 10 million years or so. But now that that possibility has been ruled out, planners at NASA and elsewhere devote their attention to smaller objects in space. Those are far more numerous, and, although they would not set off mass extinctions, they can unleash more energy than a nuclear bomb.
造成全球性影响的情况很罕见，大约每1000万年发生一次。但现在这种可能性已被排除，美国宇航局和其他地方的规划者都将注意力转向了太空中体积更小的物体。这类天体的数量更为庞大，尽管不会导致大规模灭绝，但仍能释放出比核弹爆炸还要多的能量。
“The conversation has matured in a really appropriate way,” Dr. Statler said.
“关于这个问题的讨论刚好已经成熟了，”斯塔特勒博士说。
The growing focus on planetary defense can be seen in a number of initiatives that NASA and congressional appropriators have sponsored. One is the Vera Rubin Observatory, a new telescope in Chile that is financed by the United States and will systematically scan the night sky and find thousands of potentially hazardous asteroids. Another is the NEO Surveyor, a space-based telescope that NASA is working to build. It too will find many hazardous asteroids, including some that are hard to spot from Earth.
在美国宇航局和各国会拨款机构发起的一系列计划中，都能看到对行星防御的日益关注。薇拉·鲁宾天文台就是其中一个项目，这是位于智利的一台由美国资助的新望远镜，将系统扫描夜空，寻找具备潜在破坏性的无数颗小行星。另一个项目是近地天体勘测者，这是美国宇航局正在研发的一种天基望远镜，能够发现许多危险小行星，包括很难从地球上发现的一些。
If any of those asteroids turn out to be on a collision course with Earth, the DART mission shows that deflecting them is a realistic possibility.
如果这些小行星中的任何一颗被确认处于与地球相撞的轨道上，DART任务证明使它们偏离轨道是可能实现的。
For the engineers on the mission, operated by the Johns Hopkins University Applied Physics Laboratory, the impact, at 7:14 p.m. Eastern time, marked the end of their work. The spacecraft, operating autonomously for the last four hours of its existence, successfully locked on Dimorphos.
对于执行这一约翰斯·霍普金斯大学应用物理实验室负责运营的项目的工程师来说，发生在东部时间晚7点14分的撞击标志着他们工作的结束。这一航天器的最后四个小时都是自主运行状态，并成功锁定了“双卫一”。
That is even more impressive because DART’s camera spotted Dimorphos for the first time a little more than an hour before impact. Dimorphos orbits a larger asteroid, Didymos, and until then, the smaller asteroid was lost in the glare of the larger object. DART’s navigation system then shifted its gaze toward the smaller asteroid.
更难得的是，在撞击前一个多小时，DART的摄像头首次拍到了“双卫一”的样子。“双卫一”环绕“双生星”这颗体积更大的小行星，在此之前，它始终隐藏于“双生星”的光芒之中。捕捉到其存在后，DART的导航系统就将方向对准了这颗更小的行星。
Up until five minutes before impact, mission controllers could have intervened if something had gone wrong. But they did not have to make any adjustments.
直到撞击前五分钟，一旦出现问题，任务控制人员还可以进行干预。但他们并不需要做出任何调整。
During the last five minutes, the people in the control room were spectators, too, like everyone watching the stream of photographs of Dimorphos. And then it was over. Initial analysis indicated that the spacecraft hit within about 50 feet of the target center.
在那最后五分钟里，就像所有观看一连串“双卫一”照片的人一样，控制室人员也成了观众。然后，任务就结束了。初步分析表明，航天器在距离目标中心约15米的地方成功撞击。
“I definitely feel relieved,” said Elena Adams, the mission systems engineer. “And it is absolutely wonderful to do something this amazing. And we are so excited to be done.”
“我当然感到如释重负，”任务系统工程师埃琳娜·亚当斯说。“能完成这么了不起的事真是太棒了。我们对任务的结束都无比兴奋。”
For asteroid scientists, their work is just beginning.
对于小行星科学家来说，他们的工作才刚刚开始。
By design, the crash occurred when the asteroids were fairly close to Earth.
按照设计，撞击发生在小行星距离地球相对较近的时候。
That allowed telescopes on Earth to get a good look. About 40 of them were pointed at Didymos and Dimorphos, according to NASA and the mission’s managers. So were the Hubble and James Webb space telescopes as was the camera on Lucy, another NASA spacecraft. The LICIACube, a spacecraft about the size of a shoe box built by the Italian Space Agency, trailed DART to take photographs of the impact and the plume of debris. Its trajectory was shifted to the side so that it did not also crash into the asteroid.
这样一来地球上的望远镜就可以清楚地看到。据美国宇航局和任务负责人透露，约有40架望远镜指向了“双生星”和“双卫一”。哈勃和詹姆斯·韦伯太空望远镜、以及美国宇航局另一架太空探测器“露西”号上的摄像头也是如此。意大利航天局制造的一个鞋盒大小的航天器“LICIACube”尾随着DART，拍下了撞击和碎片羽流的照片。其轨道被移至边缘，这样就不会撞到小行星上。
“There’s the rest of us that are really eagerly anticipating the impacts so that we can take our science and run with it,” said Cristina Thomas, a professor of astronomy and planetary science at Northern Arizona University and lead of the observations working group for the mission. “It’s going to be so great and such an exciting once-in-a-lifetime event that we are throwing everything that we have at it.”
“我们其他人都在热切期待着这样的撞击，这样就可以将我们的科学研究付诸实践，”北亚利桑那大学天文学和行星科学教授、该项目观测工作组负责人克里斯蒂娜·托马斯说。“那将是一场如此伟大、如此激动人心的千载难逢的盛事，我们也将为此倾尽全力。”