简介：六天前，Mark Watney成为了第一批行走在火星上的人。但一场突如其来的风暴让沃特尼被孤身一人丢在了这片寸草不生的红色荒漠中，剩余的补给也远不够撑到救援可能抵达的那一天。

     当然，Watney从思想到行动上都没有坐以待毙。小编节选的这段故事描述了主角如何实施“火星种土豆”的计划，我们会读到他如何计算出了他日常所需热量和可开发的“农场”面积（在其他章节中他分别提到了如何获得土壤、肥料和水）。他一边凭借着他的植物学家和机械工程师背景非常严谨地对抗各种问题，一边如何孤身一人、却像个段子手一样喋喋不休地吐槽自黑卖萌。

Remember those old math questions you had in Algebra class? Where water is entering a container at a certain rate and leaving at a different rate and you need to figure out when it’ll be empty? Well, that concept is critical to the “Mark Watney doesn’t die” project I’m working on.

I need to create calories. And I need enough to last the 1387 sols until Ares 4 arrives. If I don’t get rescued by Ares 4, I’m dead anyway. A sol is 39 minutes longer than a day, so it works out to be 1425 days. So that’s my target: 1425 days of food.

I have plenty of multivitamins; over double what I need. And there’s five times the minimum protein in each food pack, so careful rationing of portions takes care of my protein needs for at least four years. My general nutrition is taken care of. I just need calories.

I need 1500 calories every day. I have 400 days of food to start off with. So how many calories do I need to generate per day along the entire time period to stay alive for around 1425 days?

I’ll spare you the math. The answer is about 1100. I need to create 1100 calories per day with my farming efforts to survive until Ares 4 gets here. Actually, a little more than that, because it’s Sol 25 right now and I haven’t actually planted anything yet.

With my 62 square meters of farmland, I’ll be able to create about 288 calories per day. So I need almost four times my current plan’s production to survive.

That means I need more surface area for farming, and more water to hydrate the soil. So let’s take the problems one at a time.

How much farmland can I really make?

There are 92 square meters in the Hab. Let’s say I could make use of all of it.

Also, there are five unused bunks. Let’s say I put soil in on them, too. They’re 2 square meters each, giving me 10 more square meters. So we’re up to 102.

The Hab has three lab tables, each about 2 square meters. I want to keep one for my own use, leaving two for the cause. That’s another 4 square meters, bringing the total to 106.

I have two Martian rovers. They have pressure seals, allowing the occupants to drive without space suits during long periods traversing the surface. They’re too cramped to plan crops in, and I want to be able to drive them around anyway. But both rovers have an emergency pop-tent.

There are a lot of problems with using pop-tents as farmland, but they have 10 squares meters of floor space each. Presuming I can overcome the problems, they net me another 20 square meters, bringing my farmland up to 126.

126 square meters of farmable land. That’s something to work with. I still don’t have the water to moisten all that soil, but like I said, one thing at a time.

The next thing to consider is how efficient I can be in growing potatoes. I base my crop yield estimate on the potato industry back on Earth. But potato farmers aren’t in a desperate race for survival like I am. Can I get a better yield?

For starters, I can give attention to each individual plant. I can trim them and keep them healthy and not interfering with each other.

Also, as their flowering bodies breach the surface, I can replant them deeper, then plant younger plants above them. For normal potato farmers, it’s not worth doing because they’re working with literally millions of potato plants.

Also, this sort of farming annihilates the soil. Any farmer doing it would turn their land into a dust bowl within 12 years. It’s not sustainable. But who cares? I just need to survive for 4 years.

I estimate I can get 50 percent higher yield by using these tactics. And with the 126 square meters of farmland (just over double the 62 square meters I now have) it works out to be over 850 calories per day.

That’s real progress. I’d still be in danger of starvation, but it gets me in the range of survival. I might be able to make it by nearly starving but not quite dying.

I could reduce my caloric use by minimizing manual labor. I could set the temperature of the Hab higher than normal, meaning my body would expend less energy keeping its temperature. I could cut off an arm and eat it, gaining my valuable calories and reducing my overall caloric need.

No, not really.

So let’s say I could clear up that much farmland. Seems reasonable. Where do I get the water? To go from 62 to 126 square meters of farmland at 10 centimeters deep, I’ll need 6.4 more cubic meters of soil (more shoveling, whee!) and that’ll need over 250 liters of water.

The 50 liters I have is for me to drink if the water reclaimer breaks. So I’m 250 liters short of my 250-liter goal.

Bleh. I’m going to bed.

    还记得在代数课上遇到过的经典问题吗？水以一定速度进入某容器，并以另一个速度离开，求该容器何时变空。唔，对于我正在进行的“马克·沃特尼别死”工程来说，这个概念至关重要。

    我需要制造卡路里，足够延续1387个火星日的卡路里，直到阿瑞斯4抵达。如果阿瑞斯4救不了我，我还是得死。一个火星日比一天长39分钟，也就是说，一共有1425天，那么，我的目标就是：凑足1425天的食物。

    我有大量的复合维生素，比所需多两倍还不止。另外，每个人食物包里的蛋白质都是正常所需的五倍。省着点用，我的蛋白质补给应该够用四年。我所需要的主要营养物都不缺，最缺的是卡路里。

    每天我需要1500卡路里。我手头的食物能撑400天。那么算一下，要让我活1425天，接下来每天我得制造多少卡路里呢？

    我来帮你算。答案是大约1100。在阿瑞斯4抵达之前，我要让我的小农场每天产出1100卡路里，才能活到那一天。实际上还要更多一些，因为今天已经是第25个火星日了，可我还什么也没种。

    对于我62平米的农地来说，平均每天能产出288卡路里。为了生存，我需要将现在的生产计划翻两番。

    这意味着我需要更大的种植面积，以及更多水浇灌土地。问题得一个一个解决。

    我最多能整出多大面积的农地呢？

    栖息舱共有92平米地表面积，假设我全能用上。

    另外，还有五张空床铺。假设我把它们也铺上土。每张床大约2平米，加起来就多了10平米。现在，我们一共有102平米。

    栖息舱里还有三个试验台，每个大约2平米见方。我得留一个自用，另外两个也可以铺土。那么，又多了4平米，106了。

    我有两辆火星漫游车，它们都有加压密封系统，以便乘员在进行长时间地表活动时就可以脱掉太空服驾驶。它们的内部空间太狭小，没法栽培作物，况且我很可能还要用到它们。但两辆漫游车都有应急三角帐篷。

    用三角帐篷作农地地基的挑战不小，但每个帐篷展开来都有10平米。假设能把所有问题都摆平，它们就能贡献20平米，农场总面积就能有126平米。

    126平米的农田，这还差不多。但还是没有足够水分来浇灌这么大面积的土地，就像我刚刚说的，事情得一件一件来。

    下一件需要考虑的事：能以多高效率种植土豆？我刚才计算时所参考的是地球上的土豆产量。但那些种植土豆的农民并没有面临生死存亡的压力。能有更高产量吗？

    首先，我可以关照每一株豆苗。我能把它们播种得规规整整，照顾好每一株，不让它们相互争肥。

    再就是，在它们发芽破土之后，我可以将其移植和深埋，上面还能复种幼苗。对于一般的土豆农民而言，这么做太不划算了，因为他们要对付的是几百万株豆苗。

    我承认，这样种植将耗尽土壤肥力。是个农民都知道，要这么干，12年内他的土地就会贫瘠得像个大砂锅。这绝不是什么可持续农业。但那又怎样呢？反正我只要存活四年就够了。

    通过这些方法，大概能提高五成产量。考虑到我可以拥有126平米农田（基本上是当前62平米的两倍），我应该每天能产出850卡路里。

    这进步真不小。虽然还是有可能闹饥荒，但生存时间大大延长了。我有可能挣扎在饥饿边缘，但也许不至于完全饿死。

    我可以通过降低运动量来减少所需的卡路里。还可以将栖息舱的温度提高到平均水平以上，这样的话，身体就不用产生那么多热量来维持体温。还能砍掉一条胳膊来吃，给我补充相当一部分卡路里，同时还将降低我的总体需求。

    不，不，开玩笑的。

    假设我真能清理出那么大的面积种地。差不多的。问题是，水从哪儿来呢？从62平米扩大到126平米，10厘米厚，我需要另加6.4立方米的土壤（估计得铲死我），也意味着得再来250升水。

    留下的50升水是为了防止水循环装置故障应急用的。那么，就所需的250升水而言，我缺整整250升。

    我晕。睡觉先。

Algebra      n. 代数学

calories      n. [物] 卡路里

sol               火星日

Ares 4         阿瑞斯4

multivitamins      多种维生素

protein      n. 蛋白质

rationing      n. [计划] 定量配给

portions      n. 部分

nutrition      n. 营养

hydrate      n. 水合物；氢氧化物

bunk           n. 铺位

Martian rover      火星漫游车

occupant      n. 居住者；占有者

cramped      adj. 狭窄的；难懂的；难辨的

pop-tent      三角帐篷

moisten      vt. 弄湿；使…湿润

breach      n. 违背，违反；缺口

literally      adv. 照字面地；逐字地

annihilates      vt. 歼灭；战胜；废止

tactics           n. 策略

centimeters      n. [计量] 厘米

cubic              adj. 立方体的，立方的

shoveling      vt. 铲除；用铲挖；把…胡乱塞入

liters            [计量] 公升

reclaimer      [计] 回收程序；回收装置