科学与数学blogs.scientificamerican.com
让我们殖民土卫六（Titan）
Let's Colonize Titan
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导读
这是《科学美国人》客座博客的一篇文章，主张人类殖民太阳系应优先选择土卫六（泰坦）而非火星：泰坦有浓密大气、表面有冰和水，大气层能屏蔽部分宇宙射线，低重力加浓密大气甚至让人可以靠翅膀飞行；但作者也承认距离遥远、极寒、甲烷雨等难题。文章的核心论据是近年研究提示银河宇宙射线可能造成脑损伤，使长途火星航行风险高企。
为什么经久不衰：它把一个反直觉的太空殖民方案讲得有理有据，而评论区围绕辐射、距离与'先修好地球'的争论，十年后读来仍是同一场辩论的缩影。
HN 评论精选
应先通过生活方式与财富分配改革修好地球，再谈星际殖民。
我认为在殖民其他星球之前，应先认识到：只要对我们的生活方式做相当温和的调整（相比'走向多行星'而言），地球就能在可预见的未来轻松养活人类。若我们更看重质量而非新奇，停止食用动物性食品，并重新组织生活以住得离工作更近，就能遏制对生态系统的消耗，把能源使用降到可控水平。若重新分配财富，人口增长会放缓；若向统治者施压，他们会着手消除核武库。我们大多数问题都有简单的解决办法。解决之后，或许才能开始考虑把物种扩散到别处。
banach查看英文原文
I think that, before colonizing other planets, we should start by realizing that Earth can easily sustain human kind for the foreseeable future, given some pretty modest tweaks to our way of life (compared to "going multi-planetary" that is). If we start valuing quality over novelty, stop eating animal-based foods and re-organize to live closer to where we work, we can stop the consumption and that is taxing our ecosystem and cut energy use to manageable levels. If we re-distribute our wealth, population growth will subside. If we put pressure on our rulers, they will work to eliminate the nuclear stockpiles. There are simple solutions to most of our issues. Once we have solved them, maybe we can start thinking about spreading our species to other places.
泰坦方案在距离、严寒和辐射上并不比火星更优，论证站不住脚。
所以论点是：别去火星，因为要面对宇宙射线；改去泰坦吧——它有大气，但冷得离谱还下甲烷雨。而且我们根本去不了，因为距离近三十倍，路上照样得面对宇宙射线。我无法被说服。
sgentle查看英文原文
So, the argument is let's not go to Mars because we'd have to deal with cosmic rays. Instead, let's go to Titan, which has an atmosphere, but is ridiculously cold and rains methane. Also, we can't go there because it's nearly thirty times the distance. Plus we'd still have to deal with cosmic rays along the way. I'm not convinced.
指出文中'用水制氧再燃烧'的能量逻辑错误，同时补充飞行与坠落的物理细节。
虽然大气缺氧，但地表下的水冰可提供呼吸用氧，并用来燃烧碳氢化合物作燃料。危险信号！先电解水取氧、再拿去烧碳氢化合物，想净赚能量是不可能的。这或许可作储能方案——储存碳氢化合物可能比储氢更便宜、能量密度更高。泰坦重力弱（类似月球）加上浓密大气，人背翅膀就能飞行。翅膀掉了也不怕，着陆很容易——泰坦的终端速度只有地球的十分之一。以12英里/小时撞上岩石或硬土，方法得当或运气好可以生还，但同样可能致命。
stcredzero查看英文原文
Although the atmosphere lacks oxygen, water ice just below the surface could be used to provide oxygen for breathing and to combust hydrocarbons as fuel. Red flag! It's a nonstarter to extract oxygen from water, use it to burn a hydrocarbon, then try to come out with more useful energy than you started with. This might have some use as an energy storage scheme, as storing hydrocarbons can be cheaper and more energy dense than storing hydrogen. The weak gravity—similar to the Moon’s—combined with the thick atmosphere would allow individuals to aviate with wings on their backs. If the wings fall off, no worry, landing will be easy. Terminal velocity on Titan is a tenth that found on the Earth. A 12 mph collision with solid rock or packed dirt is survivable, given the proper technique or circumstances. It's also still potentially fatal.
殖民外星是逃避主义，改造地球远比复制地球容易，人类终将被改变。
我觉得世俗/科学界'殖民其他星球'的梦想，很像宗教悖论里'死后上天堂'的观念。按理说，我们本该先在地球上的不宜居之地做改造实验——马里亚纳海沟底部或死亡谷。如果那都轻而易举，才谈得上考虑月球、火星或泰坦。但事实上，我们正在系统性地把自己星球变得不宜居。地球是数十亿年生物改造的产物，造就了我们舒适生活所依赖的那一狭窄而高度特化的环境区间。把它吃光，远比复制它容易。答案是放下极度的傲慢和宗教式的逃避主义，对行星地球培养一些尊重，极其谨慎地前行，否则我们会发现自己的星球不再适合居住。我并非说星际旅行不可能，但我强烈反对文中'人类将保持不变'、让环境来适应我们的说法。若我们真能到达其他星球，我们会被改变得认不出自己。我认为那还非常非常遥远，且前提是我们在此期间没有自我灭绝。
tehchromic查看英文原文
I find the "colonize other planets" dream of the secular/scientific community to be most like the "you'll go to heaven when you die" idea in religious paradoxy. You would think we might have experimented with teraforming uninhabitable place here on earth - the bottom of the Mariana, or Death Valley. If that was a snap, then we might contemplate Moon or Mars or Titan. But in fact we are systematically rendering our own planet uninhabitable. Our planet is the product of billions of years of biological teraformation that has created the narrow and extremely specialized spectrum of environmental factors in which we live comfortably. It is far easier to eat that up than it is to replicate it. The answer is to drop our extreme hubris and misguided religious style escapism and instead develop some respect for planet e, and proceed with extreme caution moving forward, or we will find our own planet unfit for living on. Not saying interplanetary travel isn't possible, however I strongly disagree with the statement in the article that 'humanity will remain the same' and adapt our environment to suit us. If we make it to other planets we will be so altered we will not recognize ourselves. IMO that's a long loooong way off and requires that we don't extinct ourselves in the meantime.
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