It was, literally, a striking achievement. In the early hours of Tuesday, a Nasa spacecraft slammed into a small asteroid 11mn km from Earth, its second-by-second odyssey into oblivion captured on camera and livestreamed to a world audience.
这确实是一项惊人的成就。9月27日凌晨，美国国家航空航天局(NASA)的一艘航天器撞向一颗距离地球1100万公里的小行星，摄像机逐秒记录下了航天器完成这一自毁任务的全过程，并向全世界观众进行了直播。
The impact was meant to shunt the rock, Dimorphos — one half of a two-asteroid binary system — into a slightly tighter orbit around its bigger partner, Didymos. The orbital tweak is yet to be confirmed but, if successful, it will demonstrate that, in principle at least, humans have the knowhow to deflect asteroids heading our way.
这次撞击是为了让双卫一(Dimorphos)围绕双生星(Didymos)旋转的轨道变小。双卫一和双生星共同构成一个双小行星系统。轨道调整是否成功还有待确认，但如果成功的话，至少在原则上将证明人类有能力让朝着我们飞来的小行星偏转。
“What amazed and delighted me was that everything worked so well,” said Professor Alan Fitzsimmons, an astrophysicist at Queen's University Belfast, who will now analyse images of the impact gathered from telescopes in South Africa, Chile and Hawaii and is involved in a 2027 follow-up European Space Agency mission to the same asteroid.
贝尔法斯特女王大学(Queen's University Belfast)天体物理学家艾伦•菲茨西蒙斯(Alan Fitzsimmons)教授说：“让我惊讶和高兴的是，一切都进行得如此顺利。”他现在将分析位于南非、智利和夏威夷的望远镜采集的关于此次撞击的图像，并将参与欧洲航天局(ESA) 2027年对同一颗小行星的后续任务。
While it could take months to see if the orbital period has shifted by seconds or minutes, Fitzsimmons added, “I'm more confident today than I was 24 hours ago that if a small asteroid was on a collision course with Earth, we could do something about it.”
菲茨西蒙斯补充说，虽然要再过几个月才能知道轨道周期是改变了几秒还是几分钟，但“我今天比24小时前更有信心，如果一颗小行星要与地球相撞，我们可以做些什么”。
The good news, then, is that we can now apparently guard against the menace that killed off the dinosaurs 66mn years ago. The not-so-good news is that bigger existential risks to humanity lie closer to home.
所以好消息是，我们现在看上去可以防范6600万年前让恐龙灭绝的灾祸了。而不那么好的消息是，更大的危及人类生存的风险就在我们身边。
Asteroids are rocky objects, smaller than planets, that orbit the Sun (comets, in contrast, are made of ice, rock and gas). Most of the million-plus known specimens lie in the main asteroid belt between Mars and Jupiter. Of biggest concern are potentially hazardous ones, which are at least 140m across and have orbits that come within 7.5mn km of Earth — big and close enough to strike Terra Firma but small enough to evade early detection. That made Dimorphos the perfect target: about the right size (160m), and too distant to pose a risk.
小行星是岩石质物体，比行星小，环绕太阳运行——相比之下，彗星是由冰、岩石和气体构成的。上百万颗已知小行星大部分位于火星和木星之间的主小行星带。最令人担忧的是具有潜在危险性的小行星，即直径达140米、运行轨道距离地球在750万公里以内的小行星，这样的体积和距离使其足以撞击地球，但又小到不容易在早期侦测到。这使得双卫一成了完美的目标：大小合适（直径160米）；距离又太远，不会构成风险。
One reason why the Double Asteroid Redirection Test, or Dart, mission captivated the public was its dazzling demonstration of technical chutzpah. While most space jaunts are geared towards avoiding calamitous encounters with asteroids, planets or space debris, engineering a deliberately destructive pas-de-deux between two speeding objects in the vast emptiness of space requires exquisite precision.
“双小行星重定向测试”(Dart)之所以能吸引公众，原因之一是它展示了令人惊叹的大胆技术。虽然在太空中飞行大多数时候都要刻意避免与小行星、行星或太空垃圾发生灾难性的碰撞，但在茫茫太空中，故意让两个高速飞驰的物体发生一场毁灭性交会需要极高的精确度。
The 570kg Dart spacecraft, launched last year and guided by autonomous navigation, was travelling at about 6km/s, equivalent to 14,000mph, and designed to lock on to its target less than an hour before impact. The asteroid bullseye, meanwhile, flies through space at more than twice that speed. To see the boulder-strewn surface of Dimorphos in razor-sharp detail as Dart descended to its fate, was awe-inspiring.
这艘重达570公斤的Dart飞船于去年发射，采用自主导航系统，飞行速度约为6公里/秒，相当于1.4万英里/小时。它被设计为在撞击前不到一小时锁定目标。与此同时，它要命中的这颗小行星的飞行速度是它的两倍多。当Dart向目标靠近、准备完成自己的使命时，双卫一布满巨石的表面都清晰可见，令人油然生出敬畏之心。
More profoundly, though, the mission compels us to confront the agency we have over our destiny. Dart was humanity's first attempt at intentionally moving a celestial object, affording us a smidgen of influence over cosmic forces hitherto outside our control. Its success does not mean we can now play billiards with space rocks but it does suggest a viable line of planetary defence should heavenly forces conspire against us, as they did against the dinosaurs.
然而更深远的影响是，这项任务迫使我们直面我们对自己命运的能动性。Dart是人类刻意移动天体的第一次尝试，使我们对原本不受我们控制的宇宙力量有了一丝影响力。这次尝试的成功并不意味着我们现在可以用太空岩石打台球，但它确实表明，如果天空中的种种力量合起来对我们不利，就像它们曾经对恐龙不利一样，我们可以建起一道行星防御线。
Relief at being able to avert asteroid-induced catastrophe contrasts, though, with our relatively sanguine approach to other threats. A planetary disaster caused by an asteroid impact might happen once in a million years, suggests Lord Rees, Britain's Astronomer Royal, co-founder of the Centre for the Study of Existential Risk at Cambridge university and author of If Science is to Save Us. But, “there are other substantial threats that could happen this century”.
能够避免小行星引起的灾难固然令我们感到欣慰，但与之形成鲜明对比的是我们对其他威胁的相对不在乎的态度。英国皇家天文学家(Astronomer Royal)、剑桥大学生存风险研究中心(Centre for the Study of Existential Risk at Cambridge University)联合创始人、《如果科学能拯救我们》(If Science is to Save Us)一书的作者里斯勋爵(Lord Rees)认为，由小行星撞击引起的行星灾难可能百万年才发生一次，但是，“本世纪还可能发生其他重大威胁”。
While he regards asteroid deflection technology as prudent, Rees worries more about the misuse of biotechnology (particularly experiments that create toxic viruses), artificial intelligence, pandemics and, of late, nuclear aggression. His worst nightmare, he confesses, is a lone fanatic who slips through the governance net: “Technology gives even small groups of people the power to cause a global catastrophe, such as the release of a virus, cyber attacks on power grids or a breakdown in AI. Village idiots now have global range.”
虽然里斯认为小行星偏转技术提供很好的防范，但他更担心生物技术被不当使用（特别是制造有毒病毒的实验）、人工智能、大流行病，最近还担心核侵略。他坦言，他最害怕的是一个单枪匹马行动的疯子逃过监管网：“技术让即便是一小撮人也有能力造成全球灾难，比如病毒被释放、电网被攻击或人工智能崩溃。乡下的白痴现在能危害全球。”
When HG Wells summed up the risks to civilisation, he, too, toyed with the prospect of “some great unexpected mass” rushing “upon us out of space”. But also that “some pestilence may presently appear . . . there may come some drug or a wrecking madness into the minds of men”. Our ability to calculate our way out of an asteroid strike will count for little if we cannot restrain our own wrecking madnesses first.
H•G•韦尔斯(HG Wells)在总结人类文明面对的风险时，也曾考虑过“一些意想不到的巨大物体”从“太空中冲向我们”的可能性。但他同时也提到“可能很快会出现某种瘟疫……可能会有一些毒品或破坏性的疯狂进入人们的头脑”。如果我们不能首先抑制自己疯狂的破坏倾向，我们计算如何摆脱小行星撞击的能力将毫无意义。
,
