TED2015
Fred Jansen: How to land on a comet
佛瑞德·詹森: 如何在一颗彗星上着陆
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作为罗塞塔号任务的管理人，佛瑞德·詹森负责了一个探测器在2014年成功登陆67P/丘留莫夫彗星的项目。在这场精彩幽默的演讲中，詹森披露了一些为了让菲莱探测器登陆一颗距地球5亿公里外的彗星上而作的复杂计算——并且分享了在此过程中所拍摄的一些不可思议的照片。
Fred Jansen - Space explorer
As manager of the Rosetta mission, Fred Jansen is in charge of the project that could be instrumental in uncovering clues to the origins of life on Earth. Full bio
As manager of the Rosetta mission, Fred Jansen is in charge of the project that could be instrumental in uncovering clues to the origins of life on Earth. Full bio
Double-click the English transcript below to play the video.
00:12
I'd like to take you on the epic quest
of the Rosetta spacecraft.
of the Rosetta spacecraft.
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我想带你们进入罗塞塔号
史诗般的探险中去。
史诗般的探险中去。
00:17
To escort and land the probe on a comet,
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护送这个探测器在一颗彗星上着陆，
00:21
this has been my passion
for the past two years.
for the past two years.
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是我过去两年以来的热情所在。
00:25
In order to do that,
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为了实现这个目标，
00:26
I need to explain to you something
about the origin of the solar system.
about the origin of the solar system.
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我需要向你们解释
关于太阳系起源的一些东西。
关于太阳系起源的一些东西。
00:30
When we go back
four and a half billion years,
four and a half billion years,
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让我们回到45亿年前，
00:32
there was a cloud of gas and dust.
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有一个充满气体和灰尘的云团。
00:33
In the center of this cloud,
our sun formed and ignited.
our sun formed and ignited.
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在这个云团的中心，
我们的太阳在那里形成并燃烧。
我们的太阳在那里形成并燃烧。
00:38
Along with that, what we now know
as planets, comets and asteroids formed.
as planets, comets and asteroids formed.
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与此同时，那些现在被我们称为行星、
彗星和小行星的天体也形成了。
彗星和小行星的天体也形成了。
00:44
What then happened, according to theory,
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随后，根据理论，
00:47
is that when the Earth had cooled down
a bit after its formation,
a bit after its formation,
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在地球形成并且温度
开始降低了一些的时候，
开始降低了一些的时候，
00:51
comets massively impacted the Earth
and delivered water to Earth.
and delivered water to Earth.
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彗星极大地影响了地球，
并向地球输送了水分。
并向地球输送了水分。
00:57
They probably also delivered
complex organic material to Earth,
complex organic material to Earth,
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它们可能还向地球输送了
复杂的有机物质，
复杂的有机物质，
01:01
and that may have bootstrapped
the emergence of life.
the emergence of life.
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而那有可能诱导了生命的出现。
你们可以将这一过程与完成一个
250块的拼图相比，
250块的拼图相比，
01:04
You can compare this to having
to solve a 250-piece puzzle
to solve a 250-piece puzzle
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01:08
and not a 2,000-piece puzzle.
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而不是完成一个2000块的拼图。
01:11
Afterwards, the big planets
like Jupiter and Saturn,
like Jupiter and Saturn,
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然后，像木星和土星这样的大行星，
01:15
they were not in their place
where they are now,
where they are now,
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它们当时并不在今天所处的位置，
01:17
and they interacted gravitationally,
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它们会通过引力相互作用，
并将整个太阳系内部打扫干净了，
01:20
and they swept the whole interior
of the solar system clean,
of the solar system clean,
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01:23
and what we now know as comets
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而我们现在称为彗星的天体
01:25
ended up in something
called the Kuiper Belt,
called the Kuiper Belt,
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最终到了一个叫做“柯伊伯带”的地方，
01:27
which is a belt of objects
beyond the orbit of Neptune.
beyond the orbit of Neptune.
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这是一个海王星轨道以外的天体聚集带。
01:31
And sometimes these objects
run into each other,
run into each other,
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有时这些天体会相互碰撞，
01:34
and they gravitationally deflect,
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并且发生了重力转移，
01:37
and then the gravity of Jupiter
pulls them back into the solar system.
pulls them back into the solar system.
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木星的引力随后将它们拉回了太阳系。
01:42
And they then become the comets
as we see them in the sky.
as we see them in the sky.
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然后它们就变成了
我们在天空中所见到的彗星。
我们在天空中所见到的彗星。
01:46
The important thing here to note
is that in the meantime,
is that in the meantime,
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需要注意的重点是，在此期间，
01:49
the four and a half billion years,
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这45亿年间，
01:51
these comets have been sitting
on the outside of the solar system,
on the outside of the solar system,
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这些彗星一直安坐在太阳系之外，
01:54
and haven't changed --
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并且从没变过——
01:56
deep, frozen versions of our solar system.
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深沉、冻结版的太阳系。
01:59
In the sky, they look like this.
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在空中，它们看起来是这样的。
02:01
We know them for their tails.
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我们通过它们的尾巴认识它们。
02:03
There are actually two tails.
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这里事实上有两条尾巴。
02:04
One is a dust tail,
which is blown away by the solar wind.
which is blown away by the solar wind.
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一条是尘埃尾，是被太阳风吹出来的。
02:08
The other one is an ion tail,
which is charged particles,
which is charged particles,
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另一条是离子尾，是带电粒子，
02:12
and they follow the magnetic field
in the solar system.
in the solar system.
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它们受太阳系磁场的影响。
02:15
There's the coma,
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可以看到慧发，
02:16
and then there is the nucleus,
which here is too small to see,
which here is too small to see,
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还有慧核，小到几乎看不见，
02:19
and you have to remember
that in the case of Rosetta,
that in the case of Rosetta,
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但是你们要记住在罗塞塔号的案例中，
航天器就在那个中心像素上。
02:21
the spacecraft is in that center pixel.
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02:23
We are only 20, 30, 40 kilometers
away from the comet.
away from the comet.
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我们距离这颗彗星
只有20、30、40千米。
只有20、30、40千米。
02:27
So what's important to remember?
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那么需要记住哪些关键点呢？
02:30
Comets contain the original material
from which our solar system was formed,
from which our solar system was formed,
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彗星中含有来自太阳系
形成时的原始物质，
形成时的原始物质，
02:35
so they're ideal to study the components
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因此它们是用来研究
02:37
that were present at the time
when Earth, and life, started.
when Earth, and life, started.
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地球和生命起源时
所出现的成份的理想对象。
所出现的成份的理想对象。
02:41
Comets are also suspected
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彗星还很可能
02:43
of having brought the elements
which may have bootstrapped life.
which may have bootstrapped life.
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带来了那些引发了生命起源的元素。
02:47
In 1983, ESA set up
its long-term Horizon 2000 program,
its long-term Horizon 2000 program,
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1983年，欧洲航天局开始了
长期的地平线2000计划，
长期的地平线2000计划，
02:52
which contained one cornerstone,
which would be a mission to a comet.
which would be a mission to a comet.
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它包含了一个基础项目，
可能是一个造访彗星的任务。
可能是一个造访彗星的任务。
02:56
In parallel, a small mission to a comet,
what you see here, Giotto, was launched,
what you see here, Giotto, was launched,
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同时，一个小的造访彗星的任务，
就是你们在这里看到的乔托号，启动了，
就是你们在这里看到的乔托号，启动了，
03:01
and in 1986, flew by the comet of Halley
with an armada of other spacecraft.
with an armada of other spacecraft.
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1986年，它与其它航天器组成的
舰队飞经了哈雷彗星。
舰队飞经了哈雷彗星。
03:07
From the results of that mission,
it became immediately clear
it became immediately clear
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那次任务的结果清晰地表明，
彗星是用来研究太阳系的理想天体。
03:10
that comets were ideal bodies to study
to understand our solar system.
to understand our solar system.
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03:16
And thus, the Rosetta mission
was approved in 1993,
was approved in 1993,
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因此，1993年，罗塞塔任务被批准，
最初它被设定在2003年发射，
03:20
and originally it was supposed
to be launched in 2003,
to be launched in 2003,
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但是后来由于阿里亚娜火箭
出现问题而被取消。
出现问题而被取消。
03:24
but a problem arose
with an Ariane rocket.
with an Ariane rocket.
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然而，我们的公关部门，充满热情，
03:26
However, our P.R. department,
in its enthusiasm,
in its enthusiasm,
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03:29
had already made
1,000 Delft Blue plates
1,000 Delft Blue plates
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他们已经制作了1000个
代尔夫特蓝色瓷盘，
代尔夫特蓝色瓷盘，
03:32
with the name of the wrong comets.
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并印上了那些错误的彗星名字。
03:34
So I've never had to buy any china since.
That's the positive part.
That's the positive part.
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因此从那以后我没有买过任何的瓷器。
这是积极的一面。
这是积极的一面。
03:38
(Laughter)
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（笑声）
03:39
Once the whole problem was solved,
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在所有的问题被解决之后，
03:41
we left Earth in 2004
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罗塞塔在2004年离开了地球，
03:44
to the newly selected comet,
Churyumov-Gerasimenko.
Churyumov-Gerasimenko.
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飞向重新被选定的彗星，
丘留莫夫·格拉西缅科彗星。
丘留莫夫·格拉西缅科彗星。
03:47
This comet had to be specially selected
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这颗彗星是被特别选中的，
03:50
because A, you have to
be able to get to it,
be able to get to it,
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因为首先，你得能够到达它，
03:53
and B, it shouldn't have been
in the solar system too long.
in the solar system too long.
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其次，它没有在太阳系待太长时间。
03:56
This particular comet has been
in the solar system since 1959.
in the solar system since 1959.
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这颗特别的彗星在1959年进入太阳系。
04:00
That's the first time
when it was deflected by Jupiter,
when it was deflected by Jupiter,
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那是它被木星偏转后第一次来到太阳系，
04:03
and it got close enough
to the sun to start changing.
to the sun to start changing.
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并且它跟太阳的距离近到
足够让它发生变化。
足够让它发生变化。
04:06
So it's a very fresh comet.
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所以这是一颗非常新的彗星。
04:08
Rosetta made a few historic firsts.
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罗塞塔取得了很多历史性的突破。
04:11
It's the first satellite to orbit a comet,
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它是首个进入彗星轨道的人造卫星，
04:14
and to escort it throughout
its whole tour through the solar system --
its whole tour through the solar system --
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并且伴随彗星走过了
它的整个太阳系之旅——
它的整个太阳系之旅——
04:17
closest approach to the sun,
as we will see in August,
as we will see in August,
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到达了距离最短的近日点，
这个我们将会在8份看到，
这个我们将会在8份看到，
04:20
and then away again to the exterior.
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然后重新离开太阳系。
这是第一次有航天器在彗星上着陆。
04:23
It's the first ever landing on a comet.
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04:25
We actually orbit the comet
using something which is not
using something which is not
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我们实际上在罗塞塔号上
使用了一些通常不会在其他航天器上
使用了一些通常不会在其他航天器上
04:29
normally done with spacecraft.
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使用的彗星轨道环绕技术。
04:31
Normally, you look at the sky and you know
where you point and where you are.
where you point and where you are.
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通常，你们看看天空，
就会知道方位和坐标。
就会知道方位和坐标。
04:34
In this case, that's not enough.
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但是在这个案例中，那还不够。
04:36
We navigated by looking
at landmarks on the comet.
at landmarks on the comet.
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我们通过观察彗星上的地标来导航。
04:40
We recognized features --
boulders, craters --
boulders, craters --
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我们辨别那些特征——卵石、环形山——
04:42
and that's how we know where we are
respective to the comet.
respective to the comet.
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然后我们就知道我们处在彗星上
哪个对应的区域。
哪个对应的区域。
04:46
And, of course, it's the first satellite
to go beyond the orbit of Jupiter
to go beyond the orbit of Jupiter
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当然，这也是第一次
使用太阳能电池飞跃
使用太阳能电池飞跃
04:51
on solar cells.
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木星轨道的航天器。
04:52
Now, this sounds more heroic
than it actually is,
than it actually is,
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这听起来比事实更称得上是壮举，
04:54
because the technology
to use radio isotope thermal generators
to use radio isotope thermal generators
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因为那时放射性同位素热电机的技术
04:59
wasn't available in Europe at that time,
so there was no choice.
so there was no choice.
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在欧洲尚未得到应用，所以当时别无选择。
05:03
But these solar arrays are big.
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但是这些太阳能电池板很大。
05:04
This is one wing, and these are not
specially selected small people.
specially selected small people.
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这是它的一个侧翼，
下面这些可不是特意挑选的矮小的人。
下面这些可不是特意挑选的矮小的人。
05:07
They're just like you and me.
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他们是跟你我一样的正常人。
05:09
(Laughter)
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（笑声）
我们有两个这样的侧翼，65平米。
05:12
We have two of these wings,
65 square meters.
65 square meters.
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05:16
Now later on, of course,
when we got to the comet,
when we got to the comet,
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随后，当然，当我们飞向这颗彗星时，
05:19
you find out that 65 square meters of sail
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你们会发现扬着一个65平米的帆
05:22
close to a body which is outgassing
is not always a very handy choice.
is not always a very handy choice.
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向一个正在排气的天体靠近，
并不总是一个便捷的选择。
并不总是一个便捷的选择。
05:28
Now, how did we get to the comet?
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我们是怎么到达这颗彗星的呢？
05:30
Because we had to go there
for the Rosetta scientific objectives
for the Rosetta scientific objectives
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因为我们得去一个十分遥远的地方
去完成罗塞塔号的
去完成罗塞塔号的
05:34
very far away -- four times the distance
of the Earth to the sun --
of the Earth to the sun --
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科学目标——
是地球到太阳距离的4倍——
是地球到太阳距离的4倍——
05:38
and also at a much higher velocity
than we could achieve with fuel,
than we could achieve with fuel,
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而且以一个我们用普通燃料
无法达到的速度。
无法达到的速度。
05:42
because we'd have to take six times as
much fuel as the whole spacecraft weighed.
much fuel as the whole spacecraft weighed.
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因为我们得携带六倍于
航天器本身重量的燃料。
航天器本身重量的燃料。
05:46
So what do you do?
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那要怎么做呢？
在一个非常低的高度，大概几千公里，
05:47
You use gravitational flybys, slingshots,
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05:51
where you pass by a planet
at very low altitude,
at very low altitude,
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经过一个行星时，
利用引力的拉扯效应和
利用引力的拉扯效应和
05:54
a few thousand kilometers,
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弹力作用，
05:56
and then you get the velocity
of that planet around the sun for free.
of that planet around the sun for free.
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你就会直接获得跟那颗行星同样的
绕日运行速度。
绕日运行速度。
我们尝试过很多次。
06:01
We did that a few times.
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在地球上，火星上 ，
然后又在地球上试过两次，
然后又在地球上试过两次，
06:03
We did Earth, we did Mars,
we did twice Earth again,
we did twice Earth again,
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06:05
and we also flew by two asteroids,
Lutetia and Steins.
Lutetia and Steins.
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我们还飞掠了两颗小行星，
鲁特西亚和斯坦斯。
鲁特西亚和斯坦斯。
06:10
Then in 2011, we got so far from the sun
that if the spacecraft got into trouble,
that if the spacecraft got into trouble,
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到了2011年，我们已经距离太阳太远了，
如果这个航天器遇到问题，
如果这个航天器遇到问题，
06:14
we couldn't actually
save the spacecraft anymore,
save the spacecraft anymore,
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我们根本没办法挽救它了，
06:18
so we went into hibernation.
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所以我们进入了冬眠状态。
06:20
Everything was switched off
except for one clock.
except for one clock.
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除了一个计时器，所有的仪器都关掉了。
06:24
Here you see in white the trajectory,
and the way this works.
and the way this works.
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这里你们看到白色的是它的轨道，
以及运动轨迹。
以及运动轨迹。
06:27
You see that from
the circle where we started,
the circle where we started,
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可以看到从一开始的这个圆，
06:30
the white line, actually you get
more and more and more elliptical,
more and more and more elliptical,
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这条白线，
我们可以得到越来越多的椭圆，
我们可以得到越来越多的椭圆，
06:33
and then finally we approached the comet
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最终我们在2014年5月靠近了这颗彗星，
06:36
in May 2014, and we had to start
doing the rendezvous maneuvers.
doing the rendezvous maneuvers.
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然后我们得开始做会合减速。
06:41
On the way there, we flew by Earth and we
took a few pictures to test our cameras.
took a few pictures to test our cameras.
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在途中，我们飞经地球并拍了一些照片
以测试我们的相机。
以测试我们的相机。
06:45
This is the moon rising over Earth,
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这是月球在地球另一侧升起，
06:47
and this is what we now call a selfie,
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这是我们现在所称的自拍，
06:49
which at that time, by the way,
that word didn't exist. (Laughter)
that word didn't exist. (Laughter)
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顺便说一下，那个时候“自拍”
这个词还不存在。（笑声）
这个词还不存在。（笑声）
06:53
It's at Mars. It was taken
by the CIVA camera.
by the CIVA camera.
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这是在火星上， 由彗星红外与可见光分析仪
相机拍摄的。
相机拍摄的。
06:56
That's one of the cameras on the lander,
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那是着陆器上的一台相机，
06:58
and it just looks under the solar arrays,
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它看起来处在太阳能电池板的下方，
07:01
and you see the planet Mars
and the solar array in the distance.
and the solar array in the distance.
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你们能看到火星和太阳能电池板
出现在远处。
出现在远处。
07:05
Now, when we got out
of hibernation in January 2014,
of hibernation in January 2014,
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当我们在2014年1月从冬眠中被唤醒后，
07:11
we started arriving at a distance
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我们开始前进，并在5月份
07:12
of two million kilometers
from the comet in May.
from the comet in May.
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到达了距离这个彗星
200万公里的地方。
200万公里的地方。
07:15
However, the velocity
the spacecraft had was much too fast.
the spacecraft had was much too fast.
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然而，这个航天器的速度太快了。
07:19
We were going 2,800 kilometers an hour
faster than the comet, so we had to brake.
faster than the comet, so we had to brake.
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我们的时速要比这颗彗星快2800公里，
因此我们需要刹一刹车。
因此我们需要刹一刹车。
07:25
We had to do eight maneuvers,
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我们得做8次减速，
07:27
and you see here,
some of them were really big.
some of them were really big.
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可以看到，
其中的一些减速幅度真的很大。
其中的一些减速幅度真的很大。
07:30
We had to brake the first one
by a few hundred kilometers per hour,
by a few hundred kilometers per hour,
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我们的第一次减速需要
将速度每小时降低数百公里，
将速度每小时降低数百公里，
07:36
and actually, the duration of that
was seven hours,
was seven hours,
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事实上这个过程花了7个小时，
07:40
and it used 218 kilos of fuel,
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消耗了218公斤的燃料，
07:43
and those were seven nerve-wracking
hours, because in 2007,
hours, because in 2007,
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这也是令人心惊胆战的7小时，
因为在2007年，
因为在2007年，
07:47
there was a leak in the system
of the propulsion of Rosetta,
of the propulsion of Rosetta,
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罗塞塔号的推进系统出现了一处泄漏，
07:50
and we had to close off a branch,
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我们不得不关掉了一个分路，
07:52
so the system was actually
operating at a pressure
operating at a pressure
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因此推进系统是在超出设计能力的
07:55
which it was never designed
or qualified for.
or qualified for.
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压力下运行的。
07:59
Then we got in the vicinity of the comet,
and these were the first pictures we saw.
and these were the first pictures we saw.
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然后我们到达了这颗彗星的附近，
这是我们看到的第一批照片。
这是我们看到的第一批照片。
08:04
The true comet rotation period
is 12 and a half hours,
is 12 and a half hours,
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这颗彗星真实的自转周期是12.5个小时，
08:07
so this is accelerated,
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所以这是加速播放的，
08:09
but you will understand that
our flight dynamics engineers thought,
our flight dynamics engineers thought,
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但是你们肯定能够理解我们的
飞行动力学工程师的想法，
飞行动力学工程师的想法，
08:12
this is not going to be
an easy thing to land on.
an easy thing to land on.
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这不是一个容易登陆的东西。
08:16
We had hoped for some kind
of spud-like thing
of spud-like thing
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我们曾经幻想过它是某种
形状像土豆一样的
形状像土豆一样的
08:21
where you could easily land.
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容易登陆的东西。
08:23
But we had one hope: maybe it was smooth.
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但我们扔抱着一线希望：
也许它比较平坦。
也许它比较平坦。
08:26
No. That didn't work either. (Laughter)
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不，它的表面还很粗糙。（笑声）
08:30
So at that point in time,
it was clearly unavoidable:
it was clearly unavoidable:
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因此，当时我们迫不得已
做出了如下选择：
做出了如下选择：
08:33
we had to map this body
in all the detail you could get,
in all the detail you could get,
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我们得利用收集到的所有细节
去绘制这个天体的地图，
去绘制这个天体的地图，
08:36
because we had to find an area
which is 500 meters in diameter and flat.
which is 500 meters in diameter and flat.
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因为我们得找到一块直径500米的平地。
08:41
Why 500 meters? That's the error
we have on landing the probe.
we have on landing the probe.
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为什么是500米？
这是我们让探测器着陆时的误差。
这是我们让探测器着陆时的误差。
08:46
So we went through this process,
and we mapped the comet.
and we mapped the comet.
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于是我们立即采取行动
并绘制出了彗星表面的地图。
并绘制出了彗星表面的地图。
08:49
We used a technique
called photoclinometry.
called photoclinometry.
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我们采用了一种叫做
照相测斜术的技术。
照相测斜术的技术。
08:51
You use shadows thrown by the sun.
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利用太阳拋下的阴影。
08:54
What you see here is a rock
sitting on the surface of the comet,
sitting on the surface of the comet,
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你们现在看到的是一块
位于彗星表面的岩石，
位于彗星表面的岩石，
08:57
and the sun shines from above.
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而阳光从上面照下来。
09:00
From the shadow, we, with our brain,
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透过阴影，我们用大脑，
09:02
can immediately determine
roughly what the shape of that rock is.
roughly what the shape of that rock is.
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可以立刻大致判断出这块岩石的形状。
09:05
You can program that in a computer,
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你可以编一套那样的程序，
09:07
you then cover the whole comet,
and you can map the comet.
and you can map the comet.
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然后覆盖整颗彗星，
就可以绘制出它表面的形貌图了。
就可以绘制出它表面的形貌图了。
09:12
For that, we flew special trajectories
starting in August.
starting in August.
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为此，我们从8月份开始沿着
一种特殊的轨迹飞行。
一种特殊的轨迹飞行。
09:15
First, a triangle
of 100 kilometers on a side
of 100 kilometers on a side
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首先，在100公里外的地方沿着一个
09:18
at 100 kilometers' distance,
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边长为100公里的三角形飞行，
09:20
and we repeated the whole
thing at 50 kilometers.
thing at 50 kilometers.
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然后将三角形的边长改为50公里，
再重复整个过程。
再重复整个过程。
09:23
At that time, we had seen the comet
at all kinds of angles,
at all kinds of angles,
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那时候，我们已经通过所有的角度
观察过这颗彗星了，
观察过这颗彗星了，
09:27
and we could use this technique
to map the whole thing.
to map the whole thing.
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我们也可以利用这一技术绘制出
整个彗星的表面形貌。
整个彗星的表面形貌。
09:31
Now, this led to a selection
of landing sites.
of landing sites.
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现在，到了选择登陆地点的时候了。
09:35
This whole process we had to do,
to go from the mapping of the comet
to go from the mapping of the comet
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我们要做的就是在60天内，
通过绘制这颗彗星的形貌图，
通过绘制这颗彗星的形貌图，
09:39
to actually finding
the final landing site, was 60 days.
the final landing site, was 60 days.
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来找到一个最终的登陆地点。
09:42
We didn't have more.
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我们没有更多的时间。
09:44
To give you an idea,
the average Mars mission
the average Mars mission
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对比一下，平均来说，火星上的任务
09:46
takes hundreds of scientists
for years to meet
for years to meet
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需要成百上千的科学家花数年的时间
09:50
about where shall we go?
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去找到一个登陆地点。
09:52
We had 60 days, and that was it.
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但我们只有60天，就那么多了。
09:54
We finally selected the final landing site
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我们最终选定了一个登陆点，
09:57
and the commands were prepared
for Rosetta to launch Philae.
for Rosetta to launch Philae.
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并且让罗塞塔号发送菲莱号的
指令也准备好了。
指令也准备好了。
10:02
The way this works is that Rosetta
has to be at the right point in space,
has to be at the right point in space,
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不过前提条件是罗塞塔号
得处在空中的正确位置，
得处在空中的正确位置，
10:06
and aiming towards the comet,
because the lander is passive.
because the lander is passive.
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并且瞄准这颗彗星，因为着陆器是被动的。
10:09
The lander is then pushed out
and moves towards the comet.
and moves towards the comet.
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它需要被推出并飞向彗星。
10:13
Rosetta had to turn around
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罗塞塔号得转过身，
10:15
to get its cameras to actually look
at Philae while it was departing
at Philae while it was departing
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以便使它的相机在
菲莱飞离的过程中能对着它，
菲莱飞离的过程中能对着它，
10:19
and to be able to communicate with it.
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并且能与它进行交流。
10:22
Now, the landing duration
of the whole trajectory was seven hours.
of the whole trajectory was seven hours.
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整个着陆过程花了7个小时。
10:26
Now do a simple calculation:
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简单的计算一下：
10:29
if the velocity of Rosetta is off
by one centimeter per second,
by one centimeter per second,
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如果罗塞塔号的速度误差是1厘米每秒，
10:33
seven hours is 25,000 seconds.
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7个小时就是25000秒，
10:37
That means 252 meters wrong on the comet.
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那就意味着着陆器
登陆彗星时的误差是252米。
登陆彗星时的误差是252米。
10:42
So we had to know the velocity of Rosetta
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因此我们得将罗塞塔的速度误差
10:45
much better than
one centimeter per second,
one centimeter per second,
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精确到小于1厘米每秒，
10:48
and its location in space
better than 100 meters
better than 100 meters
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而它在太空中远离地球5亿公里的位置，
10:52
at 500 million kilometers from Earth.
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误差要精确到100米以内。
10:55
That's no mean feat.
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那不是一件易事。
10:57
Let me quickly take you through
some of the science and the instruments.
some of the science and the instruments.
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让我快速的介绍一下
其中的一些科学理论和仪器。
其中的一些科学理论和仪器。
11:02
I won't bore you with all the details
of all the instruments,
of all the instruments,
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我不会介绍所有仪器的细节，
以免你们听得一头雾水，
以免你们听得一头雾水，
11:05
but it's got everything.
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但想帮助你们了解一些概念。
11:07
We can sniff gas,
we can measure dust particles,
we can measure dust particles,
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我们可以检测气体，测量粉尘，
11:10
the shape of them, the composition,
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测它们的形状和成分，
11:12
there are magnetometers, everything.
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这里有磁力仪等等我们需要的一切。
11:15
This is one of the results from
an instrument which measures gas density
an instrument which measures gas density
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这是一部仪器所测到的
罗塞塔号所处位置的
罗塞塔号所处位置的
11:18
at the position of Rosetta,
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气体密度的结果，
11:20
so it's gas which has left the comet.
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这是从彗星上释放出来的气体。
11:22
The bottom graph
is September of last year.
is September of last year.
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下面的图是去年9月份的。
11:25
There is a long-term variation,
which in itself is not surprising,
which in itself is not surprising,
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这是一个长期的变化，
对于它本身来说可能不算什么，
对于它本身来说可能不算什么，
11:28
but you see the sharp peaks.
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但是看看那些尖峰。
11:30
This is a comet day.
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这就是彗星上的一天。
11:32
You can see the effect of the sun
on the evaporation of gas
on the evaporation of gas
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你们可以看到太阳对于气体蒸发的影响，
11:36
and the fact that the comet is rotating.
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以及彗星是旋转的这一事实。
11:39
So there is one spot, apparently,
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这里有一个点，很明显地，
11:41
where there is a lot of stuff coming from,
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很多东西都出自那里，
11:43
it gets heated in the Sun,
and then cools down on the back side.
and then cools down on the back side.
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它被太阳加热，然后在背面冷却。
11:46
And we can see
the density variations of this.
the density variations of this.
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我们可以看看这里的密度差异。
11:50
These are the gases
and the organic compounds
and the organic compounds
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这些是我们已经测量到的
11:54
that we already have measured.
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气体和有机化合物。
11:56
You will see it's an impressive list,
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看得出这是一份令人印象深刻的列表，
11:57
and there is much, much,
much more to come,
much more to come,
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并且还会有更多更多的东西出现在上面，
因为我们还进行了更多的测量。
12:00
because there are more measurements.
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事实上，这会儿正有一个
在休斯顿举行的会议，
在休斯顿举行的会议，
12:02
Actually, there is a conference
going on in Houston at the moment
going on in Houston at the moment
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12:05
where many of these results are presented.
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这些数据会在会上被展示出来。
12:08
Also, we measured dust particles.
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我们还测量了尘粒。
12:10
Now, for you, this will not
look very impressive,
look very impressive,
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对于你们来说，这可能没什么太大的意义，
12:13
but the scientists were thrilled
when they saw this.
when they saw this.
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但是当科学家们
看到这个的时候都非常激动。
看到这个的时候都非常激动。
12:16
Two dust particles:
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两颗尘粒：
12:17
the right one they call Boris,
and they shot it with tantalum
and they shot it with tantalum
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2994
右边的他们叫它鲍里斯，
他们用钽去射击它，
他们用钽去射击它，
12:20
in order to be able to analyze it.
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以便能够分析它。
12:23
Now, we found sodium and magnesium.
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我们发现了钠和镁。
12:25
What this tells you is this is
the concentration of these two materials
the concentration of these two materials
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而这也说明了这就是当太阳系刚形成时
12:29
at the time the solar system was formed,
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这两种物质的浓度，
12:32
so we learned things about
which materials were there
which materials were there
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因此我们知道了当行星形成时
12:35
when the planet was made.
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存在着哪些物质。
当然，最重要的因素之一就是成像。
12:38
Of course, one of the important
elements is the imaging.
elements is the imaging.
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12:41
This is one of the cameras of Rosetta,
the OSIRIS camera,
the OSIRIS camera,
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这是罗塞塔号上的一个相机——
奥西里斯相机——拍摄到的，
奥西里斯相机——拍摄到的，
12:44
and this actually was the cover
of Science magazine
of Science magazine
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而这实际上是《科学》杂志
12:47
on January 23 of this year.
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今年1月23日那一期的封面。
12:50
Nobody had expected
this body to look like this.
this body to look like this.
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没有人想到它看起来会是这样的。
12:54
Boulders, rocks -- if anything, it looks
more like the Half Dome in Yosemite
more like the Half Dome in Yosemite
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大卵石，岩石——相比于其它任何地方，
12:57
than anything else.
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它看起来更像是约塞米蒂的半屏岩。
13:00
We also saw things like this:
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我们还看到了这样的东西：
13:02
dunes, and what look to be,
on the righthand side, wind-blown shadows.
on the righthand side, wind-blown shadows.
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沙丘，还有在右手边，
看起来像一些被风吹动的影子。
看起来像一些被风吹动的影子。
13:07
Now we know these from Mars,
but this comet doesn't have an atmosphere,
but this comet doesn't have an atmosphere,
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我们在火星上发现过这些，
但是这颗彗星没有大气层，
但是这颗彗星没有大气层，
13:11
so it's a bit difficult to create
a wind-blown shadow.
a wind-blown shadow.
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所以要制造一个被风吹动的
影子是有点困难的。
影子是有点困难的。
13:14
It may be local outgassing,
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这可能是局部的出气，
13:16
stuff which goes up and comes back.
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有什么东西上升然后落下来。
13:18
We don't know, so there is
a lot to investigate.
a lot to investigate.
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我们还不清楚，
所以还要进行很多调查。
所以还要进行很多调查。
13:21
Here, you see the same image twice.
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这里有两张同一地点的图像。
13:23
On the left-hand side,
you see in the middle a pit.
you see in the middle a pit.
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左手边这张，中间有一个坑。
13:26
On the right-hand side,
if you carefully look,
if you carefully look,
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右手边这张，如果你们仔细看，
13:28
there are three jets coming out
of the bottom of that pit.
of the bottom of that pit.
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有三股气流从那个坑的底部喷出。
13:31
So this is the activity of the comet.
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所以这就是这颗彗星的活动。
13:34
Apparently, at the bottom of these pits
is where the active regions are,
is where the active regions are,
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显然，这些坑的底部就是活动区域，
13:38
and where the material
evaporates into space.
evaporates into space.
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也是物质蒸发到空中去的地方。
13:40
There is a very intriguing crack
in the neck of the comet.
in the neck of the comet.
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这颗彗星的脖子上
有一个非常有趣的裂缝。
有一个非常有趣的裂缝。
13:44
You see it on the right-hand side.
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就在右手边。
13:46
It's a kilometer long,
and it's two and a half meters wide.
and it's two and a half meters wide.
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它有1公里长，2.5米宽。
13:50
Some people suggest that actually,
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有些人提出，事实上
13:52
when we get close to the sun,
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当我们向太阳靠近的时候，
13:54
the comet may split in two,
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这颗彗星可能会一分为二，
13:56
and then we'll have to choose,
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然后我们不得不做出选择，
我们要去跟踪哪一半的彗星？
13:58
which comet do we go for?
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14:00
The lander -- again, lots of instruments,
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这个着陆器——
一样的，携带了很多仪器，
一样的，携带了很多仪器，
14:03
mostly comparable except for the things
which hammer in the ground and drill, etc.
which hammer in the ground and drill, etc.
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除了一些打钻用的装置，
其他大部分跟航天器上的差不多。
其他大部分跟航天器上的差不多。
14:08
But much the same as Rosetta, and that is
because you want to compare
because you want to compare
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与罗塞塔携带几乎一样的仪器是因为要把
14:12
what you find in space
with what you find on the comet.
with what you find on the comet.
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太空中发现的物质跟这颗彗星上的做比较。
14:16
These are called
ground truth measurements.
ground truth measurements.
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这被称为“地面实况调查”。
14:18
These are the landing descent images
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这些是奥西里斯相机拍摄的
14:22
that were taken by the OSIRIS camera.
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着陆下降时的图像。
14:24
You see the lander getting further
and further away from Rosetta.
and further away from Rosetta.
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可以看到着陆器离罗塞塔号越来越远。
14:28
On the top right, you see an image
taken at 60 meters by the lander,
taken at 60 meters by the lander,
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右上角，是着陆器在60米外拍的照片，
14:32
60 meters above the surface of the comet.
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彗星表面60米以上。
14:35
The boulder there is some 10 meters.
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那个大卵石直径大约10米。
14:37
So this is one of the last images we took
before we landed on the comet.
before we landed on the comet.
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这是我们在彗星上着陆之前
所拍的最后一张照片。
所拍的最后一张照片。
14:42
Here, you see the whole sequence again,
but from a different perspective,
but from a different perspective,
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换个角度，再看一遍这整个过程，
14:45
and you see three blown-ups
from the bottom-left to the middle
from the bottom-left to the middle
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大家可以看到从图中的
左下角到中间有三幅
左下角到中间有三幅
14:49
of the lander traveling
over the surface of the comet.
over the surface of the comet.
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着陆器飞过彗星表面时的放大照。
14:54
Then, at the top, there is a before
and an after image of the landing.
and an after image of the landing.
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然后，在顶部有
着陆之前和之后的对比照。
着陆之前和之后的对比照。
14:58
The only problem with the after image is,
there is no lander.
there is no lander.
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唯一的问题就是在着陆后的照片中
没有出现着陆器。
没有出现着陆器。
15:02
But if you carefully look
at the right-hand side of this image,
at the right-hand side of this image,
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但是你们仔细观察这张图像的右手边，
15:05
we saw the lander still there,
but it had bounced.
but it had bounced.
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我们看到着陆器仍然在那，
但是它被反弹了。
但是它被反弹了。
15:09
It had departed again.
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又离开了彗星表面。
15:11
Now, on a bit of a comical note here
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现在，有点滑稽的是，
15:14
is that originally Rosetta was designed
to have a lander which would bounce.
to have a lander which would bounce.
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本来在罗塞塔号的设计中，
它会携带一个能反弹的着陆器。
它会携带一个能反弹的着陆器。
15:18
That was discarded because
it was way too expensive.
it was way too expensive.
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但是因为成本太高所以就放弃了。
15:21
Now, we forgot, but the lander knew.
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我们已经忘记了这件事，
但是着陆器还记得。
但是着陆器还记得。
15:23
(Laughter)
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（笑声）
15:25
During the first bounce,
in the magnetometers,
in the magnetometers,
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第一次反弹期间，在磁力仪上，
15:27
you see here the data from them,
from the three axes, x, y and z.
from the three axes, x, y and z.
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你们可以看到来自X、Y、Z
三个坐标上的数据。
三个坐标上的数据。
15:31
Halfway through, you see a red line.
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半途中，你们可以看到一条红线。
15:33
At that red line, there is a change.
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这条红线表示有变化产生。
15:35
What happened, apparently,
is during the first bounce,
is during the first bounce,
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发生了什么呢？
很显然是在第一次反弹期间，
很显然是在第一次反弹期间，
15:39
somewhere, we hit the edge of a crater
with one of the legs of the lander,
with one of the legs of the lander,
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着陆器的一条腿在某个地方
碰到了一个坑的边缘，
碰到了一个坑的边缘，
15:44
and the rotation velocity
of the lander changed.
of the lander changed.
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然后着陆器的旋转速度被改变了。
15:47
So we've been rather lucky
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所以我们很幸运
15:49
that we are where we are.
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是处在当时的位置。
15:51
This is one of
the iconic images of Rosetta.
the iconic images of Rosetta.
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这是罗塞塔号拍的标志性的图片之一。
15:55
It's a man-made object,
a leg of the lander,
a leg of the lander,
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那是一个人造物体，着陆器的一条腿，
15:59
standing on a comet.
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站在一颗彗星上。
16:01
This, for me, is one of the very best
images of space science I have ever seen.
images of space science I have ever seen.
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对我来说，这是我见过的
最棒的空间科学的照片之一。
最棒的空间科学的照片之一。
16:06
(Applause)
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（掌声）
16:11
One of the things we still have to do
is to actually find the lander.
is to actually find the lander.
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未来的任务之一就是要找到这个着陆器。
16:15
The blue area here
is where we know it must be.
is where we know it must be.
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蓝色区域是我们知道的
它应该所处的位置。
它应该所处的位置。
16:18
We haven't been able to find it yet,
but the search is continuing,
but the search is continuing,
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我们还没能找到它，但是搜索仍在继续，
16:22
as are our efforts to start getting
the lander to work again.
the lander to work again.
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同时我们也在努力让着陆器重新工作。
16:26
We listen every day,
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我们每天都仔细监听，
希望从现在到4月份的某个时候，
16:28
and we hope that between now
and somewhere in April,
and somewhere in April,
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16:30
the lander will wake up again.
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这个着陆器会重新开始工作。
16:32
The findings of what
we found on the comet:
we found on the comet:
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我们在这颗彗星上的发现是：
16:35
This thing would float in water.
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这颗彗星可以在水上漂浮。
16:38
It's half the density of water.
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它的密度是水的一半。
16:40
So it looks like
a very big rock, but it's not.
a very big rock, but it's not.
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因此它虽然看起来像一块大岩石，
但实际上不是。
但实际上不是。
16:43
The activity increase we saw
in June, July, August last year
in June, July, August last year
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去年6到8月间我们看到
16:47
was a four-fold activity increase.
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它的活跃性提高了4倍。
16:49
By the time we will be at the sun,
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当我们靠近太阳时，
16:51
there will be 100 kilos
a second leaving this comet:
a second leaving this comet:
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每秒种将会有100公斤的物质
离开这颗彗星：
离开这颗彗星：
16:56
gas, dust, whatever.
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气体、灰尘等等。
16:57
That's 100 million kilos a day.
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1天的话就是1亿公斤。
17:01
Then, finally, the landing day.
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最终，到了着陆的那一天。
我将永生难忘——大家都疯狂了，
在德国有250名电视台工作人员争相报道。
在德国有250名电视台工作人员争相报道。
17:03
I will never forget -- absolute madness,
250 TV crews in Germany.
250 TV crews in Germany.
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17:09
The BBC was interviewing me,
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在BBC采访我的同时，
17:11
and another TV crew
who was following me all day
who was following me all day
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另一家电视台全天都在
跟踪报道我的工作人员
跟踪报道我的工作人员
17:14
were filming me being interviewed,
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也拍下了我的访问过程，
17:16
and it went on like that
for the whole day.
for the whole day.
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那种状况持续了一整天。
17:18
The Discovery Channel crew
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探索频道的工作人员
17:20
actually caught me
when leaving the control room,
when leaving the control room,
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在我离开监控室时找到了我，
17:23
and they asked the right question,
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并且提出了正确的问题，
17:25
and man, I got into tears,
and I still feel this.
and I still feel this.
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我当时激动得流下了眼泪，
而那种感觉依旧挥之不去。
而那种感觉依旧挥之不去。
17:28
For a month and a half,
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此后的1个半月里，
17:30
I couldn't think about
landing day without crying,
landing day without crying,
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每次想到着陆日我都会热泪盈眶，
17:33
and I still have the emotion in me.
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并到现在那种情绪在我心中仍然存在。
17:36
With this image of the comet,
I would like to leave you.
I would like to leave you.
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我想用这张这颗彗星的照片
来结束今天的演讲。
来结束今天的演讲。
17:38
Thank you.
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谢谢。
17:41
(Applause)
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（掌声）
ABOUT THE SPEAKER
Fred Jansen - Space explorerAs manager of the Rosetta mission, Fred Jansen is in charge of the project that could be instrumental in uncovering clues to the origins of life on Earth.
Why you should listen
Fred Jansen manages the European Space Agency’s Rosetta mission, which guided a probe into orbit around a comet and dispatched a lander to its surface -- both firsts in space exploration. Although the lander Philae could not accomplish its full mission before going into hibernation, the data it’s already gathered will immeasurably multiply our knowledge of comets and their contributions to the ingredients of life on Earth.
In addition to his work with the Rosetta Mission, Jansen oversees the ESA’s XMM-Newton, an orbiting x-ray space observatory delving into the most elusive secrets of the universe, including black holes and dark matter.
Fred Jansen | Speaker | TED.com