英国皇家科学院圣诞讲座：如何在太空中生存（2015）

他们会在边缘上站起来
they'd be on the edges, being able to stand up,
因为那将是一单位重力
because there would be one G of load.
一单位重力是我们在地球上重力 那很好
One G is the force of gravity we have on Earth, that's great.
但是那个伦敦眼的直径
But that London Eye is as big across
得跟空间站一样长
as the space station is long.
建造它很费功夫
And it takes a lot of effort to build that.
空间站就建了15年
Took 15 years to build the space station,
而把这种东西送到火星上
and sending vehicles like that to Mars
是一项很艰巨的工程挑战
is a huge, huge engineering challenge.
那么你们还有什么别的选择呢
So, what other option do you have?
2007年我在美国宇航局工作时
Well, when I worked for NASA in 2007,
参与的实验就是为了解决这个问题的
I was part of an experiment to answer that question.
我们想
And we thought,
"能不能有一台离心机
"What if you could get a centrifuge
可以放在一个普通太空舱内呢
that you could fit inside an ordinary vehicle?"
也就是说 在一个看起来是这样的模型里
So, inside a module that looks rather like that.
这种大小的物体
As big as that
能够用一架普通的火箭送上太空
that you could send up to space on an ordinary rocket.
把某个物体旋转得足够快
And you could spin something
以此获得人工重力
quite fast to generate artificial gravity.
我们这么做
And you can do that,
就能得到跟现在地面上的重力相当的离心力
you can get a centrifuge that would almost fit on the floor here,
我们有一些相关视频
and I think we've got some footage of that.
这是一部在休斯敦的短半径离心机
This is the Short Radius Centrifuge in Houston.
那是我当时在美国宇航局的导师
That is my former mentor at NASA,
现于约翰逊航♥天♥中心担任生命科学院院长一职
now the Director of Life Sciences at Johnson Space Center.
他把眼睛闭起来了
He's got his eyes closed
我想他不大喜欢在里面的感觉
cos I don't think he liked being on it very much.
你可能会说 那我们在飞去火星的途中
Now, you say, that's going to be rubbish,
什么都干不了了
flying to Mars,
在那上面没日没夜地旋转
spinning on that all day.
但是好消息是
But here's the kicker -
你不用在上面转一整天
you don't have to spin on it all day.
如果你转得足够快
If you spin really fast,
快到你得到了大于一单位重力的加速度
fast enough to give you more than one G of load,
那么你就能把这些重力
then you can give gravity like
看成是一剂药
you would give the dose of a drug.
你能每天吃两剂重力
And you can take that gravity dose twice a day
早上一小时 下午一小时
for one hour in the morning, one hour in the afternoon,
那样已经足够提供大量的保护了
and that is enough to provide quite a lot of protection.
一直视以为敌的失重
The absence of gravity which has been your enemy all along
并不是问题
isn't a problem.
事实上 重获重力才是你该担心的
Actually, when gravity returns, it is your enemy.
还有 要在火星上安全着陆
And to get safely onto the surface of Mars,
你需要能够停下来
you need to be able to stop.
火箭科学家们会告诉你
And there's one thing that rocket scientists will tell you
在所有火箭科学中
and that is that the hardest two things
最困难的两件事
in all of rocket science
就是起航和再次着陆
are starting and stopping again.
我想我们应该在到达火星前
And so I thought we should bring on an expert in stopping
请出一位着陆专家
when you get to Mars.
十分荣幸
So, it's my great, great pleasure
让我们请出特别来宾
to welcome our very special guest...
在帕萨迪那市的喷气推进实验室任职的工程师
an engineer from the Jet Propulsion Laboratory in Pasadena
好奇号♥火星探测器的主要工程师之一
and one of the lead engineers on the Mars Curiosity Rover,
安妮塔·森古普塔博士
Dr Anita Sengupta.
安妮塔... 上来给我们搭把手吧
Now, Anita... Come and give us a hand here,
你们俩
you two.
上来帮我们把这个摊开
Come and give us a hand to stretch this out.
你带来了什么
What have you got here?
这是一顶盘缝带伞
This is a disk-gap-band parachute
专门在火星上使用
and it's specially used on Mars
原因是 在火星上
and the reason for that is, on Mars,
当你进入大气层时
when you enter the atmosphere,
你是以极高速前进的
you're coming at very fast speeds,
当你展开这把伞时
and specifically when you deploy the parachute,
你是以超音速前进
you're coming in at supersonic speeds.
我现在遇到了各种动力不稳定困难...
I'm experiencing all sorts of dynamic instability here...
...整理这顶降落伞
...with our parachute.
我们是不是有一个能用的降落伞
Have we got a working version of this?
是的没错
We do, actually.
我们有一个小尺寸的版本
We have one which is a subscale version.
大小大概是在火星上所使用那顶的3%
Represents about 3% of the scale that we used on Mars
现在将给大家展示一下
which we can show you now.
好的
OK, all right. So...
现在让我们一起倒数 等待降落伞下落
We're going to count in and then release the parachute.
大家准备好了吗 3 2 1
Ready, everyone? Three, two, one.
它来了
There it goes.
太神奇了 确实
So, that is very impressive. It is.
它非常轻巧
It's very lightweight and
独特之处正是
so what's so unique about these parachutes
重量几乎为零 却异常坚固
is they weigh almost nothing, but they're incredibly strong.
比如 好奇号♥用的降落伞
For reference, the parachute that we used for Curiosity,
只有45千克
it weighed only about 100lbs
却能承受重达
but had to withstand a total load on
30000千克的压力
of it about 65,000lbs of force.
我太喜欢它了 这个设计真的很有意思
I love that. It's a very interesting design,
但我还是不明白
but I still don't get
在火星降落有什么困难
what's the fuss with stopping at Mars?
在地球上降落不是很平常的事吗
We stop at Earth all the time.
你提供了一组视频
You've got some video here actually
展示了它落在火星上的情形
of what it was like to stop at Mars.
您是这个项目主要是设计师之一
You were one of the lead engineers
就是它 神奇的好奇号♥火星探测器
for this, the Mars Curiosity Rover, which was fantastic.
它和大众甲壳虫汽车大小一致
This is the size of a Volkswagen Beetle
即将进入火星大气层
coming into Mars' atmosphere.
请给我们解释一下吧
Tell us what's happening here.
现在我们正处于超音速飞行状态
At this point we're at hypersonic flow.
已经减速到大约每小时1600千米
We've slowed down to around 1,000mph
在两倍马赫时降落伞打开
and the parachute deploys at mach 2,
这是音速的两倍 大约每小时1400千米
two times the speed of sound, around 900mph.
它一直减速到次音速状态
It continues to slow down to subsonic speeds.
这也就是它的收尾速度了
At that point, it's actually reached terminal velocity.
不能再慢了
You can't go any slower,
这时我们就会把降落伞丢掉
so you basically cut the parachute away.
随后 探测器会自♥由♥下落
Then the Rover is in freefall,
一直降到火星表面
descending towards the surface.
它会开启八个主要着陆引擎
At this point, it turns on a total of eight main landing engines,
八架火箭向着火星表面点火
eight rockets firing towards the ground
让探测器进一步减速
to slow it down even further.
一直降到每小时320千米的速度
That gets it down to around 200mph.
当接近到火星表面
As you approach the surface,
我们将开启一项神奇的操作
we start something very unique,
我们叫它天空起重机
which is called the Sky Crane manoeuvre.
这时我们第一次在火星上做这样的事
This is the first time we've ever done this on Mars.
探测器被固定在三副系绳上慢慢下落
We start to lower the Rover on a series of three tethers.
之所以这样做是因为
And the reason we do this
让探测器成为一个登陆平台
is we actually make the Rover the actual landing platform.
这样就可以使用这些强有力的引擎
And it allows us to have these big, powerful engines
继续向地面喷火
firing towards the ground,
但是与探测器和地表间
but at a safer distance away from the Rover
还有一段安全距离
and away from the surface.
之后这三副系绳会断开
Those three tethers then cut away.
火箭飞行器会以45度角飞离
That little rocket ship flies off 45 degrees
随后紧急降落
to the side and crash-lands
到此它的任务就圆♥满♥结束了
its mission is over.
这时 探测器也安全降落到火星表面了
And now the Rover is safely on the surface of Mars.
太精彩了
Wow, that's amazing.
毫无疑问
That is, hands down,
这是我所见过最棒的着陆了
the coolest landing I have ever seen.