英国皇家科学院圣诞讲座：如何在太空中生存（2015）

但是 为什么这个降落伞会有缺一块呢
But this parachute, why does it have the gap?
因为降落过程中它会经历
It has the gap because it experiences
一种超音速的不稳定状态
something called a supersonic instability.
刚刚它从天花板上降落
So, what you saw as it descended from the ceiling
是在亚音速流中
was actually in subsonic flow.
这种情况下 降落伞处于相对稳定状态
In subsonic flow, the parachute is relatively stable,
但是在超音速流中 情况完全不同
but in supersonic flow, things look entirely different.
让我们一起看一段视频
And we have a video that we can show you
这个降落伞在2.7马赫速度下展开
which actually has the parachute deploying at 2.7 mach,
这几乎是声速的三倍
which is almost three times the speed of sound.
它就像水母那样一张一合 极不稳定
What you can see is it collapses and inflates like a jellyfish.
这是我们不希望看到的
We don't want it to do that
不幸的是 在火星上它就是这样
but, unfortunately on Mars, that's what it does.
这时候会让降落伞
When it happens, you can actually cause the parachute
产生更小的空气阻力
to produce less aerodynamic drag,
无法达到减速的目的
which is what slows you down.
这个过程还会使降落支离破碎
It can actually damage the parachute and make it fall apart
所以我们十分在意
and so we were really concerned about this
好奇号♥中的这个降落伞
for the Curiosity Rover,
因为这是我们制♥造♥过最大的降落伞
cos it was the largest parachute we'd ever built,
并且还要在前所未有的高马赫下
and it also was deploying at the highest mach number
完成打开
we've ever deployed at.
这太不可思议了
That is incredible.
缺口能避免在打开时被撕裂
The gap allows it not to fall apart as it opens.
这确实很神奇
This is absolutely fantastic.
我还是把它还给你吧
I'm going to give you your parachute back
它以后还会派上用场的 好的
cos I think you might want to use it again. Yes.
请大家鼓掌感谢安妮塔·森古普塔
Anita Sengupta, everybody.
看吧 我们可以毫发无损地到达火星
So, we can get there in one piece,
安妮塔的神奇系统会让我们安全着陆
we can stop using one of Anita's incredible systems.
那么现在我们就到达火星了
And then we're there.
请看大屏幕
And up on the screen now
这是火星表面的一张图片
you can see a picture of one of the places on Mars
也是我非常向往的地方
that I would like to visit.
这是维多利亚环形山的中心
This is the very beautiful dappled
有零星的斑点 十分迷人
centre of Victoria Crater.
这座环形山真实存在
That crater, it's a real picture,
它宽780米
it's 780 metres across.
探测器曾到访这里
It's been visited by the automatic rovers
这真是名副其实的
that have been, really, the pathfinder missions
造福全人类的探索计划
for our future human exploration
我们看到了这座环形山
and we've peered into that crater.
它的表面是一层一层的沉积岩
In its walls are sedimentary rocks, layers and layers of rock
向我们诉说着火星的历史故事
that tell us about the history of Mars.
现在仍有很多未知等待探索
There is still so much left to explore,
但我们毫不畏惧
but we remain confident.
我们也已经开始研究
So much so that we've begun to think about the way
从火星返还地球的路线
we would get home from Mars.
有一种方式可以减轻你的行李负担
Now, there's a way of lightening your packing load here
使用在火星上随处可见的物质
by using what you've got all around you on Mars.
那就是二氧化碳
And that's carbon dioxide.
火星上的大气99%是由二氧化碳组成
Mars' atmosphere is about 99% carbon dioxide
它可以为你所用
and you can use that.
通过它你可以得到很重要的
It brings you some very important things
碳和氧
carbon and oxygen.
如果你身边有那么一丁点氢气的话
If you bring a little bit of hydrogen along with you,
获取碳和氧就变得极为简单
and it turns out that's quite easy to do,
通过沙巴提耶反应
then you can make some useful materials
我们可以得到有用的物质
with something called a Sabatier reaction.
这个过程中你可以
In a Sabatier reaction you can combine
将氢气和二氧化碳结合
hydrogen and carbon dioxide,
进而产生甲烷和氧气
and the product is methane and oxygen.
这两样东西足以制成火箭燃料
And that is enough to make some rocket fuel.
你可能从未想过甲烷与推动人和探测器
You don't usually think of methane as being something
进入外太空有什么联♥系♥
that can propel people and objects into space,
那么让我演示给你们看吧
so I'm going to show you.
安迪 带上护目镜
Andy, goggle time.
坐在前排的你们要注意了 很好
And I think front row goggle time. Good, all right.
我知道在你们看来 甲烷有点搞笑
I know you think of methane as being a bit of a comedy gas
因为它是奶牛们放屁时会释放的气体
that cows fart out
但事实上 它却能驱动火箭
but, actually, it can propel rockets.
这次 由安迪来点火
Now, Andy's going to light this one
因为这里有点小技巧
because there's a trick to it
他说他自己更
and he says it has a more...
之前他把这个叫做"烈焰之火"
He technically described it earlier on as a more "Flamey flame".
注意了 这就是甲烷
So, this is methane.
我们已经在回家的路上了
We are on our way home
这也是提姆和我们说再见的时候了
and there's just time for Tim to say a final goodbye.
很高兴能够在国际空间站
So, it's been great talking to everybody
和皇家科学院圣诞讲座的朋友们
at the Royal Institute Christmas Lectures
进行交流
from the International Space Station.
很遗憾不能和大家坐在一起
I'm sorry I couldn't be with you in person,
但我觉得此时能在航♥天♥器上
but I certainly think that I've got the most privileged position
鸟瞰美丽的地球
to be here onboard at the moment
是莫大的荣幸
and looking down on the beautiful planet Earth.
地球上的朋友们 再见
So, to everybody back there, goodbye.
感谢你们分享提姆的探险
Thank you all for sharing in Tim's adventure.
但你们所看到的也是我们所有人的探险
But what you've seen here has been the adventure of our lives.
你们不仅是提姆计划的缔造者
These are people who make not just Tim's mission happen
也是科学的缔造者
but all of science happen.
这是我们的旅程
This has been our adventure.
但将属于你 你
And it will be yours and yours and yours and yours and yours.
属于你们这一代
This is the adventure of your generation
现在是你们一展身手的时候了
and it's time you started it.
谢谢
Thank you.