如果不能找到新的恒星，移民新的行星，人類終將走向滅絕。

至少埃隆·馬斯克是這樣說的。這位科技行業的億萬富翁在本月早些時候的《新太空》（New Space）雜志上發表了一篇論文，詳細闡述了在火星建設“自給自足的城市”的愿景。這篇論文周三被發布在網上。

這篇共16頁的論文詳細介紹了SpaceX CEO過去幾年一直在思考的一些想法，總結了他在去年9月份墨西哥國際宇航聯大會（International Aeronautical Congress）上的演講內容。現在他把對火星之旅的大概想法變成了文字，還配上了圖表和插圖。這將更方便科學界研究他的火星移民計劃。

馬斯克的論文非常直白，在他的筆下，這段大約1.4億英里的旅程似乎沒有太大難度。他說道：“實際上有一種方法可以讓想要移民火星的人們得償所愿。”馬斯克表示，目前的主要障礙是將人類運往火星的高昂運輸成本。他估計，如果使用傳統方法，例如1969年將人類送上月球所使用的方法，每張票的成本將高達100億美元。但馬斯克心中有一個更可行的目標。

他寫道：“只要我們能將前往火星的成本降到相當于美國一套普通住房的價格，也就是大約200,000美元，我認為在火星上建設自給自足的人類文明的可能性是非常高的。我想這一定能實現。”

為了將火星之旅的成本降低“五百萬個百分點”，馬斯克列出了幾個步驟：宇宙飛船必須完全可以重復使用，可以在地球軌道上填充燃料，而在火星上建設的生產設備將生產燃料供飛船使用。馬斯克認為甲烷是理想的火箭推進劑，因為在火星上制作甲烷的技術難度要低于提取氫或其他物質的難度。他認為氫燃料的成本過高。

只要滿足了工程學方面的要求，接下來就是發射時間問題。論文中的插圖顯示，馬斯克希望最早在2023年啟動火星飛行計劃。他在論文中寫道，建立一座自給自足的城市，至少需要一百萬人口，而一艘宇宙飛船每兩年可以運送100人。他表示，按照這個速度，“在火星上建立完全自給自足的文明，需要40 - 100年”。

馬斯克在論文的一張表格中預測，2020年開始首次試飛之后，從地球飛往火星平均將需要115天時間。而且這位商業巨頭表示，整個旅程會非常有趣。

“……旅程會既有趣又令人興奮——你不會感覺擁擠或無聊，”馬斯克寫道。 “飛船上將設置駕駛艙或乘員艙，乘客可以玩失重游戲，四處飄來飄去。還會有電影、講堂、客艙和餐廳。這會是一段非常有趣的旅程。你會過得很愉快！”

馬斯克表示，這項事業需要公私合作，由SpaceX、私營部門和政府共同出資。

美國宇航局（NASA）在提供給《財富》雜志的一份聲明中表示：“NASA支持所有想要實現下一次巨大飛躍和推動人類外太空探索事業的人。我們很高興看到國際社會正在努力迎接在火星上建立可持續人類文明的挑戰。火星之旅需要政府和業內最優秀、最聰明的人才加入，火星成為一個重要的議題，令我們備受鼓舞。”

馬斯克為什么認為人類應該將火星作為移民目的地，而不是月球？

他寫道：“我認為在月球上實現人類多行星化是非常困難的，因為月球的體積遠遠小于行星。月球上沒有大氣層。資源也沒有火星豐富。月球上的一天相當于地球上28天，而火星上的一天是地球上的24.5個小時。”

他說道：“總之，火星更適合逐步增加移民人數，建立自給自足的人類文明。”（財富中文網）

譯者：劉進龍/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.