How a miniaturized atomic clock could revolutionize space exploration | Jill Seubert

Transcriber: Joseph Geni Reviewer: Camille Martínez

翻译人员: Lixing Tan

Six months ago,

六个月前，

I watched with bated breath

我屏住呼吸，激动的目睹了 美国宇航局（NASA）

as NASA's InSight lander descended towards the surface of Mars.

洞察号探测器（InSight） 在火星表面着陆的过程。

Two hundred meters,

200 米，

80 meters,

80 米，

60, 40, 20, 17 meters.

60，40，20，17 米……

Receiving confirmation of successful touchdown

接收成功触地确认的一瞬，

was one of the most ecstatic moments of my life.

是我人生中最为欣喜的时刻。

And hearing that news was possible because of two small cube sets

正是跟随洞察号 抵达火星的两个立方星系统

that went along to Mars with InSight.

让我们得以聆听这则新闻。

Those two cube sets essentially livestreamed InSight's telemetry

这两个立方星系统 把洞察号的遥感勘测直播

back to Earth,

传送回地球，

so that we could watch in near-real time

这才让我们能几乎实时地观看到

as that InSight lander went screaming towards the surface of the red planet,

洞察号探测器呼啸着 冲向这红色星球的表面，

hitting the atmosphere of Mars

以 12000 英里的最高时速

at a top speed of about 12,000 miles per hour.

冲击火星大气层。

Now, that event was livestreamed to us

是的，这一盛况竟然是从远在

from over 90 million miles away.

九千万英里之外 向我们直播。

It was livestreamed from Mars.

这是来自火星的直播。

Meanwhile,

与此同时，

the two Voyager spacecraft --

两架旅行者号（Voyager）航天器——

now, these are these two almost unbelievably intrepid explorers.

这简直是两位勇猛惊人的探险家。

They were launched

它们发射升空时，

the same year that all of us here were being introduced to Han Solo

正是我们初次知晓韩·索罗（Han Solo） （1977版《星球大战》主角）

for the first time.

的那一年。

And they are still sending back data from interstellar space

如今，40 多年过去了， 它们仍然在星际间

over 40 years later.

向我们传回信息。

We are sending more spacecraft further into deep space

现在，我们已向更远的深空 发送了比以往任何时候

than ever before.

都多的航天器。

But every one of those spacecraft out there

但是每一架冲向太空的航天器，

depends on its navigation being performed

都依赖于它所执行的、

right here at Earth

来自地球的导航，

to tell it where it is and, far more importantly,

来告知它正身处何处， 以及更重要的，

where it is going.

它将去向何方。

And we have to do that navigation here on Earth for one simple reason:

我们不得不在地球上进行导航的 一个简单的原因是：

spacecraft are really bad at telling the time.

航天器不擅长计时。

But if we can change that,

然而，如果能改变这一点，

we can revolutionize the way we explore deep space.

我们就能颠覆探索深空的方式。

Now, I am a deep space navigator,

我是一个深空导航者。

and I know you're probably thinking, "What is that job?"

我知道你们现在大概在想 “这是个什么工作？”

Well, it is an extremely unique and also very fun job.

事实上，这是一个十分独特 也非常有趣的工作。

I steer spacecraft,

从航天器与运载工具

from the moment they separate from their launch vehicle

分离那一刻起， 我就会一直操纵着航天器，

to when they reach their destination in space.

直到它抵达太空中的目的地。

And these destinations -- say Mars for example, or Jupiter --

这些目的地，例如火星，又或者木星，

they are really far away.

它们真的很遥远。

To put my job in context for you:

这样来介绍我的工作吧：

it's like me standing here in Los Angeles and shooting an arrow,

就好比我现在站在洛杉矶开始射箭，

and with that arrow, I hit a target that's the size of a quarter,

我要用这支箭射中 扎在纽约时代广场上

and that target the size of a quarter is sitting in Times Square, New York.

一个 25 美分硬币大小的靶子。

Now, I have the opportunity to adjust the course of my spacecraft

接下来，沿着它的轨迹，

a few times along that trajectory,

我有几次机会来调整航天器航道；

but in order to do that, I need to know where it is.

可是，为了做调整， 我需要知道它的位置。

And tracking a spacecraft as it travels through deep space

其实，跟踪航天器在深空中的飞行，

is fundamentally a problem of measuring time.

这本质上是一个时间测量的问题。

You see, I can't just pull out my ruler and measure how far away my spacecraft is.

要知道，我不可能掏出一把尺子， 来丈量航天器离我有多远。

But I can measure

但是，我可以测量的是，

how long it takes a signal to get there and back again.

一个信号往返所花费的时间。

And the concept is exactly the same as an echo.

这个概念与回声完全相同：

If I stand in front of a mountain and I shout,

如果我面对一座山大喊，

the longer it takes for me to hear my echo back at me,

我听到回声所需的时间越长，

the further away that mountain is.

那座山就越远。

So we measure that signal time very, very accurately,

那么，我们必须非常非常准确地 测量信号时间，

because getting it wrong by just a tiny fraction of a second

因为仅是弄错微小的、 几分之一秒钟的时间，

might mean the difference between your spacecraft safely and gently landing

就可能意味着 航天器是可以安全平稳地

on the surface of another planet

着陆在另一个星球的表面，

or creating yet another crater on that surface.

还是会在那上面撞出个陨石坑。

Just a tiny fraction of a second,

仅仅是微小的、几分之一秒钟，

and it can be the difference between a mission's life or death.

就事关任务的生死成败。

So we measure that signal time very, very accurately here on Earth,

因此，我们在地球上必须 非常非常准确地测量信号时间，

down to better than one-billionth of a second.

把误差降低到小于十亿分之一秒。

But it has to be measured here on Earth.

当然，这些测量不得不在地球上进行。

There's this great imbalance of scale when it comes to deep space exploration.

在深空探索时， 时间尺度的比例会严重失衡。

Historically, we have been able to send smallish things extremely far away,

从历史上看，我们之所以能将 很小的物体发送到极远的地方，

thanks to very large things here on our home planet.

全依赖着我们的 地球家园上的巨大物体。

As an example, this is the size of a satellite dish

例如，这是一个 圆盘卫星信号天线的大小，

that we use to talk to these spacecraft in deep space.

我们用它来和深空中的航天器对话；

And the atomic clocks that we use for navigation are also large.

而我们用于导航的原子钟 也是个庞然大物：

The clocks and all of their supporting hardware

原子钟和它所有的支持硬件

can be up to the size of a refrigerator.

加起来可以有冰箱那么大。

Now, if we even want to talk about sending that capability into deep space,

如果我们还想谈谈 将它发送到深空的可能，

that refrigerator needs to shrink down

那么这个冰箱需要缩小到

into something that can fit inside the produce drawer.

可以放进它自己的抽屉这般大小。

So why does this matter?

那么，这一点为什么要紧呢？

Well, let's revisit one of our intrepid explorers, Voyager 1.

让我们重新审视一位勇敢的探险家， 旅行者 1 号。

Voyager 1 is just over 13 billion miles away right now.

目前，旅行者 1 号 距离我们超过 130 亿英里。

As you know, it took over 40 years to get there,

正如你们所知， 它花了 40 年才行到那里，

and it takes a signal traveling at the speed of light over 40 hours

而一个信号，以光速传播 也要超过 40 个小时

to get there and back again.

才能抵达它的位置又折返。

And here's the thing about these spacecraft:

关于这些航天器就出现了一个难题：

they move really fast.

它们移动得非常快。

And Voyager 1 doesn't stop and wait for us to send directions from Earth.

旅行者 1 号并不会停下来、 等待我们从地球发送方向，

Voyager 1 keeps moving.

它仍然会继续前进。

In that 40 hours that we are waiting

在那 40 个小时中，

to hear that echo signal here on the Earth,

我们在地球上等待听到回声信号，

Voyager 1 has moved on by about 1.5 million miles.

旅行者 1 号却已经行驶了 约 150 万英里，

It's 1.5 million miles further into largely uncharted territory.

这是飞向更遥远的 未知领域的 150 万英里。

So it would be great

正因如此，

if we could measure that signal time directly at the spacecraft.

如果我们能在航天器上 直接测量该信号时间，就再好不过。

But the miniaturization of atomic clock technology is ...

可是，将原子钟小型化的技术

well, it's difficult.

难度很大：

Not only does the clock technology and all the supporting hardware

你不仅要将它和支持性的硬件

need to shrink down,

缩小，

but you also need to make it work.

还要维持一切正常运转。

Space is an exceptionally harsh environment,

太空是一个极其恶劣的环境，

and if one piece breaks on this instrument,

如果这台仪器上有一小块破损，

it's not like we can just send a technician out to replace the piece

我们不可能派遣技术人员 去更换零件

and continue on our way.

来确保它继续前进。

The journeys that these spacecraft take can last months, years,

这些航天器的旅程 可能持续数月、数年，

even decades.

甚至数十年。

And designing and building a precision instrument that can support that

因此，设计和制造可靠的精密仪器，

is as much an art as it is a science and an engineering.

既是科学和工程学，也是艺术。

But there is good news: we are making some amazing progress,

不过令人欣慰的是， 我们正在不断取得惊人的进展，

and we're about to take our very first baby steps

我们马上就要向原子钟的新时代

into a new age of atomic space clocks.

迈进重要的一小步。

Soon we will be launching

很快，我们将推出一种

an ion-based atomic clock that is space-suitable.

适用于太空的、基于离子的原子钟。

And this clock has the potential to completely flip the way we navigate.

这个时钟可能会完全颠覆 我们的导航方式。

This clock is so stable,

它非常稳定，

it measures time so well,

可以很好地测量时间：

that if I put it right here and I turned it on,

如果我把它放在这里， 开启，

and I walked away,

离开，

I would have to come back nine million years later

九百万年后，我才能目睹

for that clock's measurement to be off by one second.

它的测量累计出一秒钟的误差。

So what can we do with a clock like this?

那么，我们可以用这样的时钟做什么？

Well, instead of doing all of the spacecraft navigation

与其在地球上进行所有的航天器导航，

here on the Earth,

不如

what if we let the spacecraft navigate themselves?

让航天器自己为自己导航？

Onboard autonomous navigation, or a self-driving spacecraft, if you will,

自载自动导航， 也可以叫自动驾驶航天器，

is one of the top technologies needed

将是我们在深空

if we are going to survive in deep space.

求生存的首要技术之一。

When we inevitably send humans to Mars or even further,

在我们不可避免地需要 将人类送往火星甚至更远处时，

we need to be navigating that ship in real time,

我们将会需要能实时导航的飞船，

not waiting for directions to come from Earth.

而非等待来自地球的指引。

And measuring that time wrong by just a tiny fraction of a second

那时，即便只是 几分之一秒的时间测量误差，

can mean the difference between a mission's life or death,

都关乎任务的生死成败。

which is bad enough for a robotic mission,

这后果对于机器人任务来说 已经够糟了，

but just think about the consequences if there was a human crew on board.

对于载有人类宇航员的后果 更是不堪设想。

But let's assume that we can get our astronauts

在此，让我们先假设宇航员能够

safely to the surface of their destination.

平安到达星球表面、 抵达他们的目的地。

Once they're there, I imagine they'd like a way to find their way around.

当他们抵达后，我想象 他们会想办法找到自己的出路。

Well, with this clock technology,

那么，利用这种时钟技术，

we can now build GPS-like navigation systems

我们就能在其他行星和卫星上

at other planets and moons.

构建类似于 GPS 的导航系统。

Imagine having GPS on the Moon or Mars.

想象一下在月球或火星上有 GPS：

Can you see an astronaut standing on the surface of Mars

你是否能看到一名宇航员 正站在火星表面，

with Olympus Mons rising in the background,

奧林匹斯山在背景中缓缓升起，

and she's looking down at her Google Maps Mars Edition

而她正低头查看 火星版谷歌地图上

to see where she is

自己的位置，

and to chart a course to get where she needs to go?

并规划路线前往目的地？

Allow me to dream for a moment,

允许我再畅想一下，

and let's talk about something far, far in the future,

一个很远很远的将来，

when we are sending humans to places much further away than Mars,

我们会将人类送到 比火星遥远得多的地方，

places where waiting for a signal from the Earth in order to navigate

这些地方是如此之远，以至于 等待地球的信号再进行导航

is just not realistic.

显得不太现实。

Imagine in this scenario that we can have a constellation,

想象在这种情况下， 我们可以拥有一个星座，

a network of communication satellites scattered throughout deep space

一套散布在深空的通讯卫星网络

broadcasting navigation signals,

向四周空间传送着导航信号，

and any spacecraft picking up that signal

并且，任何收集到这信号的航天器

can travel from destination to destination to destination

都可以在不同的目的地之间航行，

with no direct tie to the Earth at all.

而这些目的地与地球没有任何联系。

The ability to accurately measure time in deep space

在深空精确测量时间的能力

can forever change the way we navigate.

可以永远改变我们的导航方式。

But it also has the potential to give us some pretty cool science.

同时，这种能力也可能 为我们提供一些蛮酷的科学知识。

You see, that same signal that we use for navigation

事实上，我们用于导航的同一信号

tells us something about where it came from

揭示着这样一些信息： 这信号来自何处，

and the journey that it took as it traveled from antenna to antenna.

以及它在天线之间传播的历程。

And that journey, that gives us data, data to build better models,

这段传播历程为我们提供了数据， 这些数据又可以建立更好的模型，

better models of planetary atmospheres throughout our solar system.

更好的模型甚至可以 包含整个太阳系的行星大气。

We can detect subsurface oceans on far-off icy moons,

我们可以探测到 遥远而冰冷的卫星地表下的海洋。

maybe even detect tiny ripples in space due to relativistic gravity.

甚至可能探测到相对论引力 在太空中激起的微小涟漪。

Onboard autonomous navigation means we can support more spacecraft,

自载自主导航意味着 我们可以支持更多的航天器、

more sensors to explore the universe,

更多的传感器去探索宇宙，

and it also frees up navigators -- people like me --

还可以解放出更多 像我这样的导航员——

to work on finding the answers to other questions.

去追寻其他问题的答案。

And we still have a lot of questions to answer.

我们还有太多的问题等待解答。

We know such precious little about this universe around us.

我们对身处的宇宙知之甚少。

In recent years, we have discovered nearly 3,000 planetary systems

近年来，我们在太阳系之外已经发现了

outside of our own solar system,

近 3000 个行星系统，

and those systems are home to almost 4,000 exoplanets.

它们是接近 4000 颗系外行星的家园。

To put that number in context for you:

为大家提供一些背景信息供参考：

when I was learning about planets for the first time as a child,

当我孩提时代第一次学习到行星时，

there were nine,

只知道 9 颗行星，

or eight if you didn't count Pluto.

如果不算冥王星的话，是 8 颗。

But now there are 4,000.

但是现在有 4000 颗。

It is estimated that dark matter

据估计，暗物质

makes up about 96 percent of our universe,

构成了我们宇宙的96％，

and we don't even know what it is.

而我们却还不清楚它是什么。

All of the science returned

我们从所有已返回的深空飞行任务中

from all of our deep space missions combined

获得的所有科学成果的总和，

is just this single drop of knowledge

也仅仅是在浩渺的

in a vast ocean of questions.

问题海洋里的一小滴知识。

And if we want to learn more,

如果我们想知道更多，

to discover more, to understand more,

发现更多，了解更多，

then we need to explore more.

我们就需要探索更多。

The ability to accurately keep time in deep space

准确地在深空测量时间的能力

will revolutionize the way that we can explore this universe,

将革命性地改变 我们探索宇宙的方式。

and it might just be one of the keys to unlocking some of those secrets

但或许，这也仅仅是 解锁宇宙珍藏秘密的

that she holds so dear.

若干钥匙中的一把。

Thank you.

谢谢。

(Applause)

（鼓掌）