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Someday, somebody's going to die on Mars.
或许某天人类会在火星上死去也不一定。
Death isn't fun to think about, so let's just assume it'll be after one of the founders of the first Mars colony has lived to a ripe old age
死亡不是什么愉快的话题，所以咱们就假设情景是这样的吧：第一批建立火星殖民地的元勋里有一个人活到了相当大的年纪，
and watched their people grow and flourish and it'll all be very peaceful.
也亲眼见证了自己子孙的繁荣成长，然后他祥和地故去了。
But no matter how or why it happens, the science of what comes next is super interesting.
不过姑且不论这件事发生的方式和原因，接下来科学要研究的课题非常之有趣。
First, any burial plans are going to have to consider international law, because there are United Nations charters against contaminating other planets.
首先，任何葬礼计划都要将国际法考虑在内，因为联合国宪章反对污染其他行星。
And unfortunately, we humans are covered in and filled with contaminating microbes.
而且，非常不幸的是，我们人类的身上遍布细菌。
And if a person is going to die on the Red Planet, all those microbes are going to have to be killed or contained.
所以，如果有人在火星上终结了生命的话，还要想办法杀菌或抑菌。
And there are a couple options for how to do it. The first is cremation, or burning a body into ashes.
怎样做呢？有几个选择，第一个选择是火葬，也就是把尸体烧为灰烬。
Fire will kill all those microbes, and it's a practice that many communities already use and have rituals around.
火葬的方式可以杀死所有细菌，这种做法很多社群已经在使用了，并且已经形成了仪式。
But there's also an alternative that's being developed specifically for use in space! It's called Body Back, and it's pretty sci-fi.
但是有人想出了一种专门用在太空里的方法哦！这种方法叫Body Back，相当具有科幻色彩。
In 2005, NASA contacted the Swedish company Promessa, which specializes in environmentally-sound burials and cremations.
2005年，美国宇航局联系了瑞典的殡仪公司Promessa，这家公司专注于提供环保的殡葬和火化服务。
NASA asked them to look into a system for handling remains that can be used in space.
美国宇航局请求这家公司研究一种能处理太空残留物的系统。
So they came up with the Body Back, which is basically just an adaptation of Promessa's existing process, although it hasn't been done to anyone on Earth yet.
于是，他们就研制出了Body Back的方法，这种方法是对Promessa公司现有流程的调整，虽然这个新流程还未对地球人采用过。
First, the body of a Mars traveler would be stuck in a weatherproof bag.
首先，要将火星上的尸体放在防风雨的袋子里。
It'd be cooled down, and then exposed to liquid nitrogen for a bit. This would deep-freeze the body and make it really brittle.
要将这个袋子进行冷却，然后在液态氮的环境中放一会儿，这样就能对尸体进行深冻，使其更容易处理。
Then, the bag would be shaken up by a machine until the body became a powder.
然后将袋子放在机器里进行摇晃，直到尸体变成粉末。
Which is really effective for saving space, and that's always important on a mission, even if it's kinda creepy.
这种方法可以有效地节省空间，而节省空间对于执行太空任务来说非常重要，虽然这种方法有点吓人。
Still, liquid nitrogen doesn't always kill bacteria. It can also preserve them, causing them to stop growing without actually dying.
不过，液态氮并不是100%杀菌，液态氮只是能控制住细菌，让细菌没法生长，虽然也并未被杀死。
So the body would have to stay in the bag forever. But it's at least an option.
在这种办法里，尸体就要永远留在袋子里了，不过这至少也是个办法。
Now, if cremation or bag of powder options aren't available, like if someone's spacesuit breaks
如果火化和这种方法都行不通的话，比如宇航员的太空服破了口，
and they're exposed to the Martian elements, the process would go a little differently.
不得已暴露于火星环境中的话，流程就要做些修改了。
For one, they'd technically be violating international law, but there would be more immediate problems at that point.
虽然从技术角度来讲，这样破坏了国际法，但当下还有更紧急的问题出现。
To know how a body would respond to being left alone on Mars, scientists can actually study a similar environment on Earth: the Atacama desert in Chile.
要想知道尸体在火星上滞留后会发生什么的话，科学家其实可以先在地球的类似环境里研究一下：智利的阿塔卡马沙漠。
The Atacama is one of the driest places in the world, and it's super high up, with peaks reaching elevations of about 6000 meters.
阿塔卡马沙漠是世界上最干旱的地方，其温度极高，顶峰海拔达近6000米。
And the higher up you are, the thinner, cooler, and drier the air. It's a little like Mars.
海拔越高，空气越稀薄，温度越低，空气越干燥，有点像火星的感觉。
Hundreds of years ago, the Atacama was a part of the Incan empire, and the Inca had a practice called capacocha.
很多年前，阿塔卡马沙漠是印加帝国的领土，以前印加帝国有人祭的仪式。
These were ritual child sacrifices, which, to be clear, are horrible,
也就是在仪式上献祭儿童，说白了，挺吓人的，
but the bodies of these children have helped scientists with research hundreds of years later.
不过这些孩子的尸体在很多年后帮助科学家进行了研究。
Because, despite all that time, the bodies haven't really decayed.
因为虽然历时很久，但这些尸体并未完全腐蚀。
In the Atacama, it's too cold and dry for bacteria to grow well, so the bodies became natural mummies.
阿塔卡马沙漠气候寒冷干燥，细菌无法快速生长，所以尸体就成了自然的木乃伊。
And that's close to what would happen on Mars, too. It's generally colder and drier than it is on Earth, so not much would happen.
这也跟火星上的情况类似，总体而言，火星的气候比地球更加寒冷干燥，所以腐蚀更不易发生。
The bacteria on or in someone's body just wouldn't grow, or would grow much more slowly,
所以尸体内外的细菌都得不到生长，或者生长速度极慢，
so it would take centuries for a body to break down, if it decayed at all.
所以尸体能分解，也需要几百年的时间。
Now, if someone died closer to the Martian equator, where the temperatures can get up to 20 degrees Celsius,
不过，如果宇航员死在了火星的赤道附近，由于那里的温度高达20摄氏度，
the bacteria inside their body might start to decompose it for a while.
所以其体内的细菌不需要多久就会开始分解尸体了。
But the process wouldn't go on forever. That's because Mars also has super high levels of bacteria-killing radiation that would finish the job.
不过分解的过程不会一直进行，这是因为火星上杀菌辐射的强度极高，会阻止分解的进行。
You're probably familiar with UVA and UVB radiation from sunscreen and sunglasses labels, but Mars also has an extra kind: UVC, which has a shorter wavelength.
大家很可能已经从防晒霜和太阳镜的标签里得知了长波紫外线辐射和中波紫外线辐射，火星上也有类似的辐射，叫短波紫外线，其波长更短。
Our atmosphere is capable of filtering out all UVC radiation, so life on Earth isn't great at dealing with it.
地球的大气层可以滤掉所有的短波紫外线，所以地球上的生命不是很擅长应对这种紫外线。
UV-C is also especially deadly, because those shorter wavelengths carry a lot more energy.
短波紫外线也尤为致命，因为其中携带了大量的能量。
So it would probably kill most of the surviving microbes.
所以会杀死大多数残留的细菌。
So if someone died on Mars and there was no way to recover the body, or turn it into a powder, it would probably become a mummy over thousands of years.
所以，如果宇航员死在了火星上，而且没有办法火化或者将尸体变为粉末的话，尸体很可能会在很多年后变为木乃伊。
Admittedly, there is a chance some of those bacteria could survive the UVC radiation, thanks to certain mechanisms that can repair radiation damage.
无可否认的是，细菌还是有可能在短波紫外线的辐射下存活下来的，因为细菌中有一定的机制可以修复辐射所带来的损伤。
If they did, they would probably decompose the body over time.
一旦机制起作用，细菌很可能还是会随着时间的流逝对尸体进行分解。
But then Mars would be home to a bunch of radiation-resistant bacteria, which is a whole new problem. Or horror movie.
那以后呢，火星上就会有很多抗辐射的细菌存在，这就成了新的问题。可以说是恐怖至极。
And that's probably why the United Nations would require bodies to be sterilized or contained.
这可能也是联合国要求对尸体进行杀菌和抑菌措施的原因。
Thinking about people dying on Mars isn't exactly something NASA or any other space agency really wants to do,
宇航员在火星上出事儿并不是美国宇航局等空间机构真正想要思考的事情，
but it's an important part of planning for the future.
但这是为未来规划的一个重要部分。
And even if it is a little morbid, the science behind it is definitely worth thinking about. Thanks for watching this episode of SciShow Space!
虽然有点恐怖，但其背后的科学道理绝对是值得思考的，感谢收看本期的《太空科学秀》！
If you've ever wondered what would happen if someone died in the vacuum of space, we've actually talked about that, too.
如果您想知道人类在真空的空间里故去会发生什么的话，我们在之前的视频里也有讲过哦。
You can watch our episode all about it over at the main SciShow channel.
您可以在《太空科学秀》的主频道里找到相关的集锦。
