TE||Spreading life to other planets
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导读
火星移民
科学家拟使用“细菌盒”建造人类基地
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音乐| 精读 | 翻译 | 词组
Spreading life to other planets
太空殖民
本文英文部分选自经济学人Science and Technology版块
Colonising the galaxy is hard. Why not send bacteria instead?
（既然）星系殖民很难，那为什么不先移民细菌呢？
Seeding alien worlds with terrestrial life is now being discussed
在外星球繁殖地球生命的探讨
SCIENCE fiction is filled with visions of galactic empires. How people would spread from star system to star system, and communicate with each other in ways that could hold such empires together once they had done so, is, though, very much where the “fiction” bit comes in. The universal maximum speed of travel represented by the velocity of light is usually circumvented by technological magic in such works. The truth is that, unless there has been some huge misunderstanding of the laws of physics, human colonisation of the galaxy will be hard.
科幻片充满了银河帝国的场景。然而，人们如何在星系之间通行，以及假设真的能星系旅行，那么如何使这些帝国（星系）连在一起，相互交流，这是非常“科幻”的场景。在这些科幻作品中，通常会通过技术奇迹突破宇宙中的速度极限（即光速）。而事实是，除非我们对物理定律存在极大的误解，不然人类很难在星系中实现殖民。
A number of scientists reckon a more modest approach towards spreading life to other star systems might be possible. In the chill of deep space, bacteria somehow shielded from cosmic radiation might survive dormant for millions of years. Perhaps alien worlds could be seeded deliberately with terrestrial micro-organisms that might take hold there, jump-starting evolution on those planets.
一些科学家认为，有一个更为可行的方法，使得向其他星系转移生命成为可能。外太空的温度很低，以某种方式屏蔽宇宙辐射的细菌或许可以蛰伏生存几百万年。如果有意地在外星世界播种一些能在此生存的地球微生物，也许会在那些星球上进化并有质的飞跃。
There are many obstacles to directed panspermia, as this approach is known—and they are not just technical. Religiously minded critics claim “we’re playing God”, says Claudius Gros, a physicist at Goethe University in Frankfurt, who has floated the idea of scattering photosynthesising bacteria and algae on extrasolar planets. Critics argue in particular that “contaminating” other planets with terrestrial life in this way risks altering, or even destroying, any life that has arisen there independently.For support, they point to present-day concerns that bacteria carried by spacecraft might, if some form of life does exist there, do exactly that to Mars. This debate is hypothetical for now. But it will become more urgent if any of the projects currently being discussed to build probes to travel to nearby star systems gets off the drawing board and into space.
已知的定向泛种论有很多的障碍，且并不只是在技术层面上的。当法兰克福歌德大学的物理学家Claudius Gros称其想在太阳系以外的星球上播种能进行光合作用的细菌和藻类时，宗教评论家们指责这是在“扮演上帝”。有些评论家尤其反对以这种方式用地球上的生命“污染”其他星球，因为这对于那些外星球上已独自生存的生命体而言是有极大风险的，甚至是毁灭性的。为获得支持，他们指出目前的担忧，如果火星确实存在某种形式的生命，那么由航天器携带的细菌可能会对其产生这样的影响。虽然这场辩论目前都只是假设，但是一旦对于发射探测器到附近的星系的讨论不再是纸上谈兵时，那么这一担忧会变得更加紧迫而现实。
The seedling stars
可播种的星球
One such proposal, sponsored by NASA, is called the Starlight project. Another, the brainchild of Yuri Milner, a Russian venture capitalist, is the Breakthrough Starshot. Both draw on the ideas of Philip Lubin of the University of California, Santa Barbara (UCSB). Dr Lubin suggests using powerful lasers to push craft attached to light sails in the direction of nearby star systems—probably starting with Alpha Centauri, the nearest of the lot. Light sails are thin, reflective sheets large enough for the pressure exerted by beams of light shone at them to provide a meaningful accelerating force in the vacuum of space. Though no such sail has yet been propelled by lasers, the principle of light-sailing has been established by spacecraft deploying sunlight-driven sails, which have successfully accelerated them.
一个是由NASA发起的，被称为星光计划的提议。而另一个创意计划是突破摄星（Breakthrough Starshot），由俄罗斯风险投资家尤里米尔纳提出。两者都借鉴了加州大学圣巴巴拉分校（UCSB）的Philip Lubin的想法。Lubin博士建议使用强大的激光器将带飞船的太阳帆（light sails）推向附近星系 - 可能是从最近的地区Alpha Alphaauri开始。 太阳帆是薄型反光板，当足够强的光压加于在它们的面板之上时，可以在太空真空中提供重要的推进力。尽管以激光推动太阳帆的想法还未能实践，但是有太阳能驱动帆的太空船曾经成功加速，这确立了太阳帆驱动的原则。
If the sail is big enough, the craft small enough (say, a gram or two) and the laser powerful enough, then acceleration to a significant fraction (20% or so) of the speed of light should be possible. That makes journeys to Alpha Centauri (just over four light-years away) and other nearby stars a meaningful proposition. The idea is that, by the time such lasers could be built—perhaps within a couple of decades—electronics will have shrunk to a point where a spacecraft weighing a gram could carry meaningful instruments. It could also, though, carry quite a lot of bacteria.
如果风帆足够大，飞船足够小（比如说一两克），并且激光功率足够大，那么应该是有可能加速到光速的20%，这个速度已经很快。这使得去半人马座阿尔法星（Alpha Centauri）（距离四光年多）和其他附近恒星指日可待。也就是说，当能造出这种激光器的时候（可能在几十年内），电子设备将已经可以缩到很小，即便航天器自重仅一克，但仍可携带重要仪器。它当然也可以携带相当多的细菌。
Solar sails (also called light sails or photon sails) are a form of spacecraft propulsion using the radiation pressure (also called solar pressure) from stars to push large ultra-thin mirrors to high speeds.
太阳帆（英文名：Solar sails）是利用太阳光的光压进行宇宙航行的一种航天器。由于这种推力很小，所以航天器不能从地面起飞，但在没有空气阻力存在的太空，这种小小的推力仍然能为有足够帆面面积的太阳帆提供 10e－5～ 10e－3g左右的加速度。（来源：百度百科）
At the Starlight project, for which UCSB is the operational headquarters, entertaining the idea of seeding other planets with life involves a certain amount of doublethink. Even looking into taking small, simple animals such as tardigrades along to see how they react to the journey is deemed too controversial for NASA, and thus has to be done on the other side of a metaphorical Chinese wall in the university—despite the fact that an animal could not possibly survive and breed without its supporting ecosystem.
加州大学圣塔芭芭拉分校是星光项目的执行中心，在这个项目中，传播生命体到其他星球需要三思。即便是拿一些体格较小的、简单的动物，比如缓步动物类，来研究观察它们在经次行程后的反应，对于NASA而言是很具有争议性的，因此在学校开展这些实验时，不得不对外保密，尽管没有生态系统支撑，动物不太可能存活并繁殖。
定向泛物种论：指支持将一些已有物种定向运输到另一处具有繁殖潜力但目前荒凉的环境，另后者逐渐发展出指定的生态的想法。
As a private venture, Breakthrough Starshot suffers no such constraint. Although Gregory Matloff, a physicist at New York City College of Technology who is one of Dr Milner’s advisers, says that this project, too, has yet to make up its mind on the question of sending germ packages, that position is not an actual “no”.
由于是私人投资，突破摄星（Breakthrough Starshot）计划的推行并未受到类似约束。尽管Gregory Matloff（纽约科技大学的一位物理学家，并且现在是Dr Milner的顾问）尚未就运载胚芽作出决定，但并没有对此真正的说“不”。
突破摄星(Breakthrough Starshot)是霍金于2016年4月宣布联合互联网投资人尤里·米尔纳启动一项计划，以更好地了解宇宙，给科学和太空探索带来革命性的变化。
https://baike.so.com/doc/23640956-24196421.html
One practical problem would be delivering such packages. They would be unlikely to survive collision with a planet at one-fifth light speed, so the craft carrying them would need to slow down beforehand. But this is not part of the plan for either Starlight or Breakthrough Starshot. They both envisage fly-by missions. The apparatus needed for deceleration would be too heavy.
（这些计划将面临）一个现实问题是如何运载这些地球种子包。以20%的光速和星球撞击，种子包不太可能生存下来，所以载运种子包的太空飞船需要提前减速。但这并不是Starlight 和Breakthrough Starshot计划的一部分，他们设想的都是近天体飞行，而加上减速设备将会过重。
For visionaries looking into the more distant future, however, weight is less of a problem. Those who really want to seed the universe with life are happy to do it slowly. Dr Gros, for one, imagines missions that might take thousands of years to arrive. For these, craft weighing kilograms rather than grams could be involved.
但是，对于那些看向更远的将来的远见人士而言，重量将不是大问题。那些真的想要把生命传播到宇宙的人更乐意慢慢地去完成这件事。举个例子，Dr Gros正在想象一项可能需要几千年才能完成的任务。为了完成那些任务，可能会使用重达数千克的飞船，而非几克重的。
That would nevertheless require some serious rethinking of both the spacecraft and their living payloads. The threat to a craft of a long journey in deep space is that its electronics might be wrecked. Radiation, of which space is full, slowly displaces atoms in solids, to the detriment of any electronic components those atoms are part of. But if such electronics were heated periodically by a thermoelectric generator that employed radioisotopes—a widely used power source that has no moving parts—most of the dislocated atoms would recover their prior positions, Dr Gros says.
格罗博士称，然而，这需要重新认真地研究宇宙飞船及现有有效载荷。在漫长的太空旅行中，电子设备可能遭到毁坏，这是宇宙飞船在深邃的太空中会遇到的威胁。辐射遍及宇宙的每个角落，缓慢地取代了固体中的原子，从而损害了由这些原子组成的任何电子元件。但是如果利用放射性同位素（一种广泛使用的无移动部件的电源）的热电发电机定期地给这些电子设备加热，那么大部分脱位的原子会回到先前的位置。
注释：
1. 太空辐射：是一种包含伽玛射线、高能质子和宇宙射线的特殊混合体。至今，人类的航天员基本上从未经历过完全剂量的太空辐射。即使是长年运转的国际空间站，由于它的轨道也仅仅只在地球上空的400千米处。而我们的地球球体通过低层大气的折射，在宇宙射线到达国际空间站之前已经拦截掉了其中最具危险的三分之一粒子，还有三分之一则被地球磁场给反射掉了。仅仅只有很少部分的宇宙射线打到了人体的身上。所以，太空辐射的实际危险远不是我们实验室里能估计得到的情况。（百度百科）
2. Payload : |ˈpeɪləʊd; 美 -loʊd| the equipment carried by a spacecraft or satellite （航天器、卫星的）装备the passengers and goods on a ship or an aircraft for which payment is received （飞机、船只的）有效载荷，有酬负载;the goods that a vehicle, for example a lorry/truck, is carrying; the amount it is carrying （车辆等的）装载货物，装载量;the explosive power of a bomb or a missile （炸弹、导弹的）爆炸力，炸药量
The threat to the bacterial payload is similar—too much radiation breaking up the complex molecules of life. To deal with that Hajime Yano of JAXA, Japan’s space agency, suggests that the DNA in organisms on panspermia missions should be modified for extra robustness using the techniques of synthetic biology. This may sound ambitious, but at least one natural organism, a bacterium called Deinococcus radiodurans, has a DNA-repair mechanism that can rebuild genes correctly after heavy exposure to radiation.
细菌的有效承受力面临着相似的威胁——过多的辐射会粉碎复杂的生命分子。日本宇宙科学研究所（JAXA）的矢野 创（Hajime Yano）建议利用合成生物技术改良承担生源使命的生物的DNA，以增强它们的承受力来应对威胁。这听起来似乎野心勃勃，但至少有一种叫做耐辐射球菌（Deinococcus radiodurans）的天然细菌，具备DNA修复机制，可以在经受严重辐射后正确地重建基因。
注释：
JAXA 日本宇宙科学研究所 http://www.isas.jaxa.jp/
To deliver the cargo of such a craft on arrival at a target planet, Dr Gros suggests it could first decelerate by opening a large loop of copper and superconducting ceramics with a burst of electricity. The current in this loop (which would circulate indefinitely, because a superconductor has no resistance) would create a magnetic field that gradually transferred the craft’s kinetic energy to hydrogen atoms in the interstellar medium. Once in the target planet’s gravitational field, the craft could use a tiny electromagnetic rail gun to fire payloads of microbes out of the back at a speed which cancelled out the craft’s forward motion. These payloads would then fall gently to the planet’s surface.
格罗博士建议，为了让载货宇宙飞船运抵目标行星，飞船可以先通过打开一个巨大铜环和超导陶瓷形成的电回路来减速。这个回路中的电流（因为超导体没有电阻，电流会无限循环，）会产生一个磁场，把飞船的动能逐渐转移到星际介质中的氢原子上。一旦飞船落入目标行星的重力场中，就可以使用一个微小的电磁轨道炮，将负载微生物的装备从背后发射出去，发射速度会抵消飞船持续前进的动力，因此这些装备可以慢慢地降落到行星表面。
Why anyone would go to all this trouble is an intriguing question. Enthusiasts for the idea of directed panspermia, such as Michael Mautner, a biochemist at Virginia Commonwealth University who is the founder of the Interstellar Panspermia Society, say that if life has any purpose, surely it is to propagate. For him, that is enough. Some privately go further, seeing missions to oxygenate the atmospheres of sterile planets as preparing the ground for human colonisation in the far-distant future. That really is long-term thinking. Such a process would probably take hundreds of thousands, if not millions of years.
为什么人们爱去探讨这个话题是个很令人好奇的问题。一些定向泛物种论的狂热者，比如弗吉尼亚联邦大学的生物化学学家迈克尔·玛特内——星际泛物种社会的创立者认为，如果生命是有意义的，那无疑就是繁衍。对于他来说，繁衍就是一切。一些人会看得更远，试图在没有生机的星球上供氧，用以在遥远的未来的人类殖民做准备。那的确是长期的考虑，但这样的过程就算用不了几百万年，也会有几十万年。
As for fears that terrestrial organisms could interfere with life that may exist elsewhere, most proponents of directed panspermia agree that missions should be limited to lifeless worlds. Indeed, if it turns out that life is common elsewhere then the whole idea would be rather pointless. A few, though, consider such precautions unnecessary, arguing that if terrestrial organisms prove more fit to survive on an alien world than life that may be there already, well, that is what evolution is all about. But this remains a fringe view, sometimes derided as “galactic imperialism”.
至于对地球生物会干涉某处已有生命的担忧，大多定向泛物种论者认为该任务应限制在无生命世界里。的确，如果生命普遍存在于宇宙，那这个想法就有点没有意义了。然而一些人觉得这些预防措施也没有必要，他们认为如果相比于原生物种，地球生物证明更适合生存在外星世界，那就是物种进化的结果。但这是一个非主流意见，有时被认为是“银河系霸权主义”。
Imperial Earth
地球帝国
How to tell from far off whether a planet is indeed inhabited is a matter of debate. Some argue that it will be obvious from the atmosphere. No alien astronomer would doubt, looking at the amount of methane in Earth’s oxygen-rich air, that something odd and probably biological was going on there—for methane is rapidly converted by oxygen into carbon dioxide and water. Mars, however, shows no sign of such chemical disequilibrium, yet many still hope it might prove to support a small amount of simple life.
如何从远处判断一个星球是否有物种栖息还存在争论。一些人认为当然是从大气层就知道。看看地球上富含氧气的空气中甲烷的含量，没有外星旅航者会怀疑有一些奇怪的、可能是生物的东西曾在此演化——因为甲烷能与氧气快速反应转化为二氧化碳和水。虽然火星目前没有信号显示有这种的化学反应趋势存在，但目前仍有许多人期望这反应能证明简单生命的存在。
The case of Mars is, indeed, pertinent. Despite stringent attempts to sterilise Mars-bound craft, Chris McKay, an astrobiologist at NASA, thinks a lot of terrestrial bacteria are already there. He calculates that Curiosity, one of NASA’s Mars rovers, delivered almost 300,000 of them by itself. Those clinging to exposed parts of the rover have probably been killed by radiation in the 5½ years since it landed. But the rest—about half, he reckons, sheltered inside the vehicle—are probably dormant but alive. Were the planet’s atmosphere ever to thicken it would screen radiation, warm Mars and allow rain. The creatures would then seep out and begin reproducing, “happy as pigs in mud”, he says.
火星确实存在这种情况。NASA的太空生物学家Chris McKay认为，虽然飞向火星的宇宙飞船都经过严格的消毒程序，但还是有很多的地球细菌附着在飞船上。经计算，他认为NASA的“好奇号”火星探测车带去了30万细菌。探测车登陆火星后的5½年，那些附着在探测车表面外露部分的细菌很可能已被辐射杀灭。但是，他认为仍会存在近半的细菌潜藏在探测车内，它们很大可能是活着的，不过可能是处于休眠状态。如果火星大气层变厚，那么就可以遮挡辐射，整个星球变暖，出现降雨，生物就会开始出现并繁殖，用他的话来说，细菌会“快乐得像泥地里的猪一样。”
Mars’s atmosphere may eventually thicken naturally, as an ageing sun puts out more heat and evaporates now-frozen carbon dioxide. But that will take hundreds of millions of years. Should people, Dr McKay asks, use their knowledge of greenhouse gases to accelerate the process, possibly thus making the place inhabitable by humans? Or should they remove their bug-harbouring gear from Mars, to avoid all risk of the bugs spreading? There is no consensus on these questions, nor on the wider ones of directed panspermia beyond the solar system. But those tempted to squash such efforts before they have even begun might ponder an intriguing fact. Life seems to have arisen surprisingly rapidly on Earth. One explanation for this is that terrestrial life is itself a gift which arrived from a distant living world. Perhaps it is time to pass the favour on.
随着日益老化的太阳散发出更多的热量，目前处于冰冻状态的二氧化碳将会蒸发，火星大气层最后可能会自然地增厚。但是这个过程需要上亿年的时间。McKay博士提出，如果人们运用温室气体的相关知识加快这一进程，是否有可能将火星变成适合人类居住的地方？又或者人们是否应该将这些细菌附着的设施撤出火星，防止任何细菌的繁殖？对于这些问题，以及外太空的定向泛种论这些更加宽泛的问题，目前尚无定论。但是那些在还没开始行动就已经打压这些努力的人可能会思考一个有意思的现实情况。生命在地球上似乎是以出人意料的速度繁衍。对此有一种解释是，地球生命本身是一份来自遥远国度的礼物。现在可能到了将这一恩惠传递的时候了。
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早在几年前，太空迷们已在Quora上展开讨论：为什么不向火星和其他星球运送细菌。高频回答和此文中提到的顾虑一样——地球生命极有可能污染到其他星球上潜在生命体的生存环境。如今，我们已得知科学家们提出了细菌运输的设想。其目的是为了埋下创造适合人类居住星球的伏笔还是防生命体随着地球的毁灭而灭绝？如果是为了人类日后的外星移民计划。先不考虑运输和细菌进化的时间成本。即便通过运输细菌人为营造了一个有生命的星球，这些曾经来自地球的生命体会如何进化与变化，能否为地球人服务并共存，都有太多的不稳定性和不可测性。
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