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Climate change is happening, and some of its effects are already here.
气候变化正在悄然发生，其产生的一些影响已经显现了。
If we want to avoid the worst of them in the future, we're going to need to stop pumping greenhouse gasses into our atmosphere.
如果我们想避免未来产生最为恶劣的影响，就要阻止温室气体排放到大气中。
Within the next couple of decades, our energy will have to be 100% clean.
未来几十年里，我们的能源必须实现100%清洁。
We've got lots of renewable energy sources here on Earth, but at this point, we need to consider every possible option. Like the Moon!
地球上有很多可再生能源，但此时的我们应该将每条出路都考虑一下。比如月球这条出路！
According to some research, it could offer solutions to our power problems that are literally out of this world.
一些研究表明，月球可为我们的能源问题提供解决方案，这是非常棒的。
One way the Moon could give us a hand is by helping us make use of the virtually unlimited free energy pouring out of the Sun.
月球能有所助益的一方面是帮助我们充分利用太阳发出的无限能量。
Every square meter of space at the Earth's orbit receives about 1.36 kilowatts of energy.
地球轨道上每平方米的空间可以接收大概1360瓦特的能量。
Harnessing that power would give us all the electricity we need, but it's not quite as simple as it sounds.
如果能充分利用这部分能量，我们就有了所需的电能来源。但说起来容易做起来难。
By the time it filters through our atmosphere and strikes the Earth's surface, around 75% of that power is lost.
等这部分太阳光穿过大气层射到地球表面时，75%的能量都流失了。
On top of that, most solar panels available today convert less than 20% of that remaining 340 watts into electricity.
而且目前可用的太阳能电池板从太阳能到电能的转化率只有不到20%。所以这340瓦特还要再打个折扣。
And, of course, all this only works during the day.
还有就是显而易见的一点——这件事只能白天做。
A lot of these problems could be solved by putting the panels in space, where they could receive 100% sunlight, 100% of the time.
这些问题中的很多都能通过将太阳能电池板放在太空中来解决，因为在这里,太阳能电池板可以获取100%的日光和100%的时间。
But even with reusable rockets, it's not cost-effective to lift so much mass into orbit.
但即便使用可重复利用的火箭，要将这么大坨物体运送到轨道中的性价比也不高。
So that's where the Moon comes in. Each point on the Moon is in darkness for half the month, so putting solar panels on the Moon isn't the best idea.
这时候就想到了月球。月球上的所有点每个月都有一半的时间处于黑暗中，所以将太阳能电池板放在月球上并不是一个好主意。
But some researchers have proposed that we could send a robotic solar-panel factory there instead.
但一些研究人员提出，我们可以将机器人版的太阳能电池工厂发送到月球。
It could harvest the resources needed to build solar panels from things like the lunar regolith.
这样就可以收集所需的能源，并通过月表土这样的东西来构建太阳能电池板了。
Then, we could launch the panels into space from the Moon, where gravity is a lot weaker, which would be way cheaper than launching from Earth.
然后，我们可以将这些电池板从月球发射到太空中，因为月球的重力更弱，所以发射成本比从地球发射要低。
The power could be beamed back home using microwaves, and our energy problems would be solved!
只要使用微波，就能将这些能量传送回地球，就能解决我们关于获取能量的问题啦！
Then again, it's safe to say that self-assembling, robotic, laser-shooting solar panels are definitely science fiction for now.
不过，实打实地说，自我组装的、机器人型激光太阳能电池板目前还是天方夜谭。
Thankfully, the Sun doesn't just have to be our source of power.
值得庆幸的是，太一样并不是我们唯一的能量来源。
It can also be the model for how we make power.
这也可能作为我们产生能量的模型。
At its core, the Sun is powered by nuclear fusion, the process of building larger elements from smaller ones.
从本质上来说，太阳的能量是由核聚变获得的。聚变就是将小元素构建成大元素。
For many atoms, this act releases a tremendous amount of power.
很多原子在这个过程中会释放出大量能量。
Building fusion reactors here on Earth offers the promise of nearly limitless clean energy, if we can get them operational.
在地球上建造聚变反应堆后，一旦投入运营，就有希望实现无线的清洁能源。
We're probably just a couple decades away from getting it to work, is what scientists have been saying since the 1950s.
很有可能再过几十年，聚变反应堆就能开始使用，这句话从上世纪50年代开始，科学家就在一直说。
Fusion is a simple concept that has proven incredibly hard to actually put into practice.
聚变这个概念虽然简单，但很难证明实施。
We've made controlled fusion reactions before, but it takes more energy to start and control them than the fusion itself provides.
以前我们也做过可控制的聚变反应，但启动并控制聚变所需的能量比聚变反应本身所能提供的能量要多。
And an energy source that needs more energy than it produces is not ideal.
而如果一个能量来源需要的能量比产出的能量多，那不够理想。
But if we ever do get it working, we'll need fuel for the reactors.
但如果我们实施起来，就会需要给反应堆提供燃料。
In principle, any light element can be used, but one scientists are especially interested in is helium-3, a type of helium with one fewer neutron than normal.
原则上来讲，任何轻元素都是可以使用的，但有一个氢元素是科学家尤为感兴趣的，那就是氦-3。这类氦元素的中子比正常氦原子少一个。
When it's combined with deuterium, a kind of hydrogen,
氦-3一旦跟重氢（氢的同位素）混合在一起，
it forms a reactor fuel with one very attractive property: no radioactive waste.
就会形成一种反应堆燃料，这类燃料有一个非常吸引人的特质——不会产生放射性废弃物。
The problem is getting the ingredients. While deuterium can be mined from ocean water, helium-3 is much harder to get.
问题在于如何获取原料。重氢可以从海洋水源中获取，但氦-3获取的难度就更大了。
Whether you're on Earth or the Moon, once helium reaches the surface, it's eventually lost to space forever, because it's too light for our gravity to hold on to it.
无论是在地球还是月球，氦抵达地表后，都会流失在太空中，因为它质量太小，重力也留不住它。
On Earth, that makes it a depleting resource. But on the Moon, it's renewable.
地球上的氦是不断枯竭的资源，但在月球上，氦是可再生能源。
That's because the Sun's solar wind, the stream of particles coming from our star, is full of helium-3.
这是因为太阳风（来自太阳的离子束）里面富含氦-3。
Earth's magnetic field shields us from most of the solar wind, but since the Moon lacks a magnetic field, that wind constantly strikes its surface.
地球的磁场会帮我们阻隔大部分太阳风，但由于月球没有磁场，所以太阳风会不断撞击月球表面。
In effect, that deposits atoms of helium-3 underground.
最终导致月球地表下存有氦-3原子。
So, if we mine the lunar surface, voila, reactor fuel! Well, eventually.
所以如果探寻月球表面的话，就会发现反应堆燃料。所以来源问题解决了。
To get one just one gram of helium-3, you'd need to mine 150 million metric tons of lunar soil.
要获得1克氦-3，就需要挖掘1.5亿公吨的月球土壤。
Maybe that's easier than self-replicating solar panels, but I wouldn't call it easy.
或许这可能比自我复制的太阳能电池板要简单，但我依然觉得难度不小。
The good news is, there's one way the Moon is already helping us generate power.
好消息是：月球已经在以一种方式产生能量了。
In fact, if you're by the ocean, you might be seeing it right now: the tides!
住在海边的朋友可能已经感受到了——潮汐！
For something that seems like it should be really simple, the tides are weirdly complicated, but the basic idea is that the Moon's gravity feels stronger when we're facing it and weaker when we're not.
从某种角度来看，应该很简单，潮汐是很复杂的，但基本观点是——月球的吸引力在我们与月球相对时更强；反之则更弱。
That makes the water levels rise and fall. And since the oceans weigh a lot, their motion contains a vast supply of energy.
这种引力的变化会导致潮起潮落。而由于海洋的质量很大，所以移动过程中会蕴含着巨大的能量。
Engineers have come up with two pretty clever ways to use this motion to generate electricity.
工程师巧思了2种方法可以通过海洋运动来发电。
One is the tidal barrage, which is basically a gate that traps the rising tide inside.
一种是防潮堤，这是一扇门，可以将涨起的潮困在里面。
Then, when the tide falls, the water rushes out through holes in the gate and drives a turbine along the way to create electricity.
而潮落的时候，水会从门上的洞口冲流出去，让路上的涡轮驱动起来，从而发电。
Some designs even drive the turbine as the trap is filling, too.
有些设计是让涡轮在潮涨时也启动。
Tidal barrages are already being used in Canada, China, France, Russia, and South Korea, so this isn't just theoretical.
防潮堤在加拿大、中国、法国、俄罗斯、韩国已经在使用了，所以这并非只是纸上谈兵。
Another method builds on something you might have seen out in the country: wind turbines.
第二种方法要基于一种大家可能已经见过的东西——风力涡轮机。
These tidal turbines are much more expensive to build than their land-based cousins, but can also generate more power because moving water carries more energy than moving air.
这类涡轮机比陆地的涡轮机成本高，但也能发电，因为水流的能量比空气要大。
Test projects have been built in Scotland and South Korea, with one in development for New York City.
目前，苏格兰和韩国都有测试项目在建，纽约也正在研发。
On their own, they won't solve our energy problem, but the reality is that no one method will.
光靠涡轮机是不能解决能源问题的，但其他方法也不能单靠自己来完成。
We'll need to generate electricity in all sorts of ways, and some of that could be powered by the Moon.
我们需要采用各种方法来发电，月球就是一条路。
Just in case you need another reason to love our little satellite.
希望大家对这颗地球的卫星有更大的好感。
Thanks for watching this episode of SciShow Space!
感谢收看本期的《太空科学秀》！
We think the universe is fascinating, and that by understanding how it works and our place in it, we can learn a little about ourselves along the way.
我们认为宇宙很有趣，在了解宇宙运作以及地球作用的过程中，我们对自己也有了更多的了解。
If you'd like to keep up with our latest videos, you can go to youtube.com/scishowspace and subscribe.
如果大家想持续了解最新的视频集锦，可以订阅youtube.com/scishowspace。
