只要花20万美元就能去火星生活？马斯克说可以

如果不能找到新的恒星，移民新的行星，人类终将走向灭绝。

至少埃隆·马斯克是这样说的。这位科技行业的亿万富翁在本月早些时候的《新太空》（New Space）杂志上发表了一篇论文，详细阐述了在火星建设“自给自足的城市”的愿景。这篇论文周三被发布在网上。

这篇共16页的论文详细介绍了SpaceX CEO过去几年一直在思考的一些想法，总结了他在去年9月份墨西哥国际宇航联大会（International Aeronautical Congress）上的演讲内容。现在他把对火星之旅的大概想法变成了文字，还配上了图表和插图。这将更方便科学界研究他的火星移民计划。

马斯克的论文非常直白，在他的笔下，这段大约1.4亿英里的旅程似乎没有太大难度。他说道：“实际上有一种方法可以让想要移民火星的人们得偿所愿。”马斯克表示，目前的主要障碍是将人类运往火星的高昂运输成本。他估计，如果使用传统方法，例如1969年将人类送上月球所使用的方法，每张票的成本将高达100亿美元。但马斯克心中有一个更可行的目标。

他写道：“只要我们能将前往火星的成本降到相当于美国一套普通住房的价格，也就是大约200,000美元，我认为在火星上建设自给自足的人类文明的可能性是非常高的。我想这一定能实现。”

为了将火星之旅的成本降低“五百万个百分点”，马斯克列出了几个步骤：宇宙飞船必须完全可以重复使用，可以在地球轨道上填充燃料，而在火星上建设的生产设备将生产燃料供飞船使用。马斯克认为甲烷是理想的火箭推进剂，因为在火星上制作甲烷的技术难度要低于提取氢或其他物质的难度。他认为氢燃料的成本过高。

只要满足了工程学方面的要求，接下来就是发射时间问题。论文中的插图显示，马斯克希望最早在2023年启动火星飞行计划。他在论文中写道，建立一座自给自足的城市，至少需要一百万人口，而一艘宇宙飞船每两年可以运送100人。他表示，按照这个速度，“在火星上建立完全自给自足的文明，需要40 - 100年”。

马斯克在论文的一张表格中预测，2020年开始首次试飞之后，从地球飞往火星平均将需要115天时间。而且这位商业巨头表示，整个旅程会非常有趣。

“……旅程会既有趣又令人兴奋——你不会感觉拥挤或无聊，”马斯克写道。 “飞船上将设置驾驶舱或乘员舱，乘客可以玩失重游戏，四处飘来飘去。还会有电影、讲堂、客舱和餐厅。这会是一段非常有趣的旅程。你会过得很愉快！”

马斯克表示，这项事业需要公私合作，由SpaceX、私营部门和政府共同出资。

美国宇航局（NASA）在提供给《财富》杂志的一份声明中表示：“NASA支持所有想要实现下一次巨大飞跃和推动人类外太空探索事业的人。我们很高兴看到国际社会正在努力迎接在火星上建立可持续人类文明的挑战。火星之旅需要政府和业内最优秀、最聪明的人才加入，火星成为一个重要的议题，令我们备受鼓舞。”

马斯克为什么认为人类应该将火星作为移民目的地，而不是月球？

他写道：“我认为在月球上实现人类多行星化是非常困难的，因为月球的体积远远小于行星。月球上没有大气层。资源也没有火星丰富。月球上的一天相当于地球上28天，而火星上的一天是地球上的24.5个小时。”

他说道：“总之，火星更适合逐步增加移民人数，建立自给自足的人类文明。”（财富中文网）

译者：刘进龙/汪皓

Humanity will go extinct unless it reaches for the stars and colonizes a new planet.

That's what Elon Musk says, at least. The tech billionaire wrote a new paper detailing his vision for a "self-sustaining city" on Mars that was published in the scientific journal New Space earlier this month and posted online Wednesday.

The 16-page commentary details ideas the SpaceX CEO has been mulling over for years and most recently presented at the International Aeronautical Congress in Mexico last September. But his outline for the journey is now available in print, complete with accompanying charts and illustrations. Now, the scientific community will be able to scrutinize the proposal at its convenience.

Musk writes the paper in such a candid manner that he almost makes the roughly 140 million mile trip seem easy. " There really is a way that anyone could go if they wanted to," he says. The main obstacle, Musk argues, is the high cost of transporting people to the red planet. Using traditional methods like the approach that was used to send men to the moon in 1969, he estimates that it would cost about $10 billion per ticket. Musk has a much more feasible target in mind.

"If we can get the cost of moving to Mars to be roughly equivalent to a median house price in the United States, which is around $200,000, then I think the probability of establishing a self-sustaining civilization is very high," Musk writes. "I think it would almost certainly occur."

In order to achieve that price point, Musk outlines several steps to improve the cost of Mars travel by "five million percent": Spaceships must be fully reusable, they should be able to refuel in orbit, and then once again on Mars with fuel that is yielded from production plants built on the planet. Musk states that methane is the ideal propellant because the technical challenges to harvest it on Mars are significantly easier than substances like hydrogen, which he says is too expensive.

Once the engineering demands are met, it would be time to take off — which Musk is hopeful could begin as soon as 2023, according to an illustration in the paper. At least one million people would be needed to establish a self-sustaining city, he writes, estimating that spacecraft would be able to accommodate 100 people every two years. At that rate, he says it'll take "40-100 years to achieve a fully self-sustaining civilization on Mars."

A table in Musk's paper shows estimates that ships departing from Earth will take an average of 115 days to get to Mars once initial test flights begin in 2020. And the trip will be highly entertaining, according to the business mogul.

"... It has got to be really fun and exciting — it cannot feel cramped or boring," Musk writes. "Therefore, the crew compartment or the occupant compartment is set up so that you can do zero-gravity games — you can float around. There will be movies, lecture halls, cabins, and a restaurant. It will be really fun to go. You are going to have a great time!"

Musk says that ultimately the undertaking will be an enormous public private partnership funded between SpaceX, the private sector and the government.

"NASA applauds all those who want to take the next giant leap – and advance human exploration in deep space. We are very pleased that the global community is working to meet the challenges of a sustainable human presence on Mars," the space agency said in a statement to Fortune. "This journey will require the best and the brightest minds from government and industry, and the fact that Mars is a major topic of discussion is very encouraging."

And why should mankind look towards Mars instead of, say, the Moon, according to Musk?

"I think it is challenging to become multi-planetary on the moon because it is much smaller than a planet," he writes. "It does not have any atmosphere. It is not as resource-rich as Mars. It has got a 28-day day, whereas the Mars day is 24.5 hours.

"In general, Mars is far better-suited ultimately to scale up to be a self-sustaining civilization," Musk says.