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

Transcriber: Joseph Geni Reviewer: Camille Martínez

譯者: Lilian Chiu 審譯者: Helen Chang

Six months ago,

六個月前，

I watched with bated breath

我摒息看著

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

美國太空總署的洞察號登陸器 朝火星表面下降。

Two hundred meters,

兩百公尺，

80 meters,

八十公尺，

60, 40, 20, 17 meters.

六十、四十、二十、十七公尺。

Receiving confirmation of successful touchdown

聽到確認成功著陸的那一刻，

was one of the most ecstatic moments of my life.

是我人生中最狂喜的時刻之一。

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

我之所以能夠聽到那新聞，是因為

洞察號帶著兩組小型 立方體一起去火星。

that went along to Mars with InSight.

Those two cube sets essentially livestreamed InSight's telemetry

基本上，那兩組立方體的功能是

把洞察號的遙測即時傳送回地球，

back to Earth,

so that we could watch in near-real time

讓我們可以透過幾乎即時的直播，

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

看到洞察號登陸器朝向 這個紅色星球的表面呼嘯而去，

hitting the atmosphere of Mars

接觸到火星的大氣，

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

行進的最高速度大約是 每小時一萬兩千英里。

Now, that event was livestreamed to us

這個事件是從至少 九千萬英里之外的地方

from over 90 million miles away.

直播給我們觀看。

It was livestreamed from Mars.

從火星上直播。

Meanwhile,

同時，

the two Voyager spacecraft --

這兩艘航海家太空船——

now, these are these two almost unbelievably intrepid explorers.

它們可說是大膽無畏到了 難以置信程度的探險家。

They were launched

發射它們的那一年，

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

正是我們初次聽到韓索羅 這個名字的那一年。

for the first time.

And they are still sending back data from interstellar space

超過四十年之後，它們仍然繼續

從星際空間將資料送回來。

over 40 years later.

We are sending more spacecraft further into deep space

我們現在送上深太空的太空船

than ever before.

比以往都還要多。

But every one of those spacecraft out there

但在太空中的每一艘太空船

depends on its navigation being performed

都仰賴地球上的導航

right here at Earth

告訴它目前的所在，

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

以及更重要的，它的目的地。

where it is going.

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

我們必須要在地球上 做導航的理由很簡單：

spacecraft are really bad at telling the time.

太空船真的不怎麼會看時間。

But if we can change that,

但，若我們能改變這一點，

we can revolutionize the way we explore deep space.

就能為探索深太空的方式 帶來革命性的改變。

Now, I am a deep space navigator,

我是深太空導航員，

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

我知道各位可能在想： 「這是什麼工作？」

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

這是個非常獨特且很有趣的工作。

I steer spacecraft,

我為太空船掌舵，

from the moment they separate from their launch vehicle

從太空船脫離發射載具開始，

to when they reach their destination in space.

一直到它們抵達太空中的目的地。

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

這些目的地—— 比如火星或木星——

they are really far away.

非常遙遠。

To put my job in context for you:

用個比喻來幫助各位 了解我的工作：

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

就像是我站在洛杉磯 這裡射出一支箭，

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

我用這支箭射中了 二十五分硬幣大小的目標，

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

且那個二十五分硬幣大小的目標 還是位在紐約的時代廣場。

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

我有幾次機會可以沿著那軌道

a few times along that trajectory,

來調整太空船的路線，

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

但若要做到這一點， 我必須要知道它在哪裡。

And tracking a spacecraft as it travels through deep space

而基本上，在深太空中 追蹤行進中的太空船所在，

is fundamentally a problem of measuring time.

基本上就是一個測量時間的問題。

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

我不能只是拿出一把尺 來測量我的太空船有多遠。

But I can measure

但我能測量

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

訊號到那裡再回來所花的時間。

And the concept is exactly the same as an echo.

這個概念和迴音完全一樣。

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

如果我面對著一座山大叫，

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

如果那座山比較遠，我就要

等比較久才會聽到我自己的迴音。

the further away that mountain is.

So we measure that signal time very, very accurately,

我們要非常非常精確地 測量那訊號時間，

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

因為就算誤差不到幾分之一秒，

might mean the difference between your spacecraft safely and gently landing

也可能會決定你的太空船是

安全輕輕地在另一個 星球的表面著陸，

on the surface of another planet

or creating yet another crater on that surface.

還是在那星球表面上 再撞出一個坑。

Just a tiny fraction of a second,

只差幾分之一秒，

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

就可能決定任務的成敗。

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

所以我們在地球上 對訊號時間的測量

做到非常非常精確， 精確到十億分之一秒。

down to better than one-billionth of a second.

But it has to be measured here on Earth.

但測量必須要在地球上進行。

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

探索深太空的尺度嚴重不平衡。

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

在過去，

我們已經能把很小的東西 送到極遠的地方，

thanks to very large things here on our home planet.

歸功於地球這裡的大東西。

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

舉例來說，我們和在 深太空的太空船聯絡的

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

衛星碟形訊號接收器這麼大。

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

而我們用來導航的原子鐘也很大。

The clocks and all of their supporting hardware

鐘本身以及所有相關支援硬體

can be up to the size of a refrigerator.

差不多和一個冰箱一樣大。

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

如果我們想要把 那樣的能力送上深太空，

that refrigerator needs to shrink down

就需要縮小尺寸，

into something that can fit inside the produce drawer.

縮到大約能放進冰箱的蔬果室。

So why does this matter?

這為什麼很重要？

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

咱們先回顧我們其中一個 大膽無畏的探險家，航海家一號。

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

航海家一號目前在 一百三十億英里外的地方。

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

各位都知道，到那裡 要花至少四十年的時間，

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

以光速行進的訊號

要花至少四十個小時來回。

to get there and back again.

And here's the thing about these spacecraft:

而太空船有一個特性：

they move really fast.

它移動得很快。

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

航海家一號並不會停下來 等我們從地球發送指示過去。

Voyager 1 keeps moving.

航海家一號會不斷移動。

In that 40 hours that we are waiting

我們在地球上等著訊息反射回來的

to hear that echo signal here on the Earth,

那四十個小時中，

Voyager 1 has moved on by about 1.5 million miles.

航海家一號已經移動了 大約一百五十萬英里。

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

也就是朝向相當未知的領域 又前進了一百五十萬英里。

So it would be great

所以，我們很希望能直接

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

在太空船上測量訊號時間。

But the miniaturization of atomic clock technology is ...

但，要把原子鐘技術給微型化……

well, it's difficult.

嗯，很困難。

Not only does the clock technology and all the supporting hardware

不僅要把原子鐘技術

和所有相關的支援硬體都縮小，

need to shrink down,

but you also need to make it work.

還得要讓它能運作。

Space is an exceptionally harsh environment,

太空是個極度嚴酷的環境，

and if one piece breaks on this instrument,

如果這儀器有一個地方壞掉了，

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

我們可沒辦法就 派一個技師去更換零件

and continue on our way.

然後繼續進行下去。

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

這些太空船的旅程可能

長達數個月、數年，甚至數十年。

even decades.

And designing and building a precision instrument that can support that

設計和打造能夠支援 這種旅程的精準儀器，

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

涉及的不僅是科學和工程， 也涉及藝術。

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

但，好消息是： 我們有很了不起的進展，

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

我們即將朝太空原子鐘的新世紀

into a new age of atomic space clocks.

邁出小小的第一步。

Soon we will be launching

我們很快就會推出

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

一個適合太空的離子式原子鐘。

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

這個原子鐘可能可以 完全顛覆我們導航的方式。

This clock is so stable,

這個原子鐘相當穩定， 能把時間測量做得很好，

it measures time so well,

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

如果我把它放在這裡並啟動它，

and I walked away,

我走開了，

I would have to come back nine million years later

等到這個鐘的測量誤差達到一秒鐘，

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

需要我回來調整時， 已經是九百萬年後了。

So what can we do with a clock like this?

有了這樣的鐘，我們能做什麼？

Well, instead of doing all of the spacecraft navigation

現在所有的太空船導航 都還是在地球上進行，

here on the Earth,

what if we let the spacecraft navigate themselves?

如果我們能改成 讓太空船自己導航呢？

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

機上的自動導航， 或稱為自動駕駛的太空船，

is one of the top technologies needed

是我們在深太空中生存

if we are going to survive in deep space.

所必要的主要技術之一。

When we inevitably send humans to Mars or even further,

我們遲早會把人類送上火星 或送到更遠的地方，

we need to be navigating that ship in real time,

那時，那艘太空船 會需要即時導航，

not waiting for directions to come from Earth.

而不是等待地球發送指令。

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

如果那時間的測量有一點點誤差，

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

就可能決定任務的生死，

which is bad enough for a robotic mission,

對機器人任務而言， 這就已經夠糟了，

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

想想看，若太空船上有人類， 會發生怎樣的後果。

But let's assume that we can get our astronauts

但，假設我們可以把太空人 安全地送到目標星球的表面。

safely to the surface of their destination.

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

我想，他們抵達那裡之後 會希望有辦法可以找到方向。

Well, with this clock technology,

有了這種原子鐘技術，

we can now build GPS-like navigation systems

現在我們可以打造出 類似 GPS 的導航系統，

at other planets and moons.

在其他行星和衛星上使用。

Imagine having GPS on the Moon or Mars.

想像一下，在月球 或火星上有 GPS 可以用。

Can you see an astronaut standing on the surface of Mars

你們能不能想像 太空人站在火星表面上，

with Olympus Mons rising in the background,

背後是高聳的奧林帕斯山，

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

而她正低頭看著 她的火星版 Google 地圖，

to see where she is

找出她在哪裡，

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

並規劃出她到目的地要走的路線？

Allow me to dream for a moment,

讓我作一下美夢，

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

咱們來談談非常遙遠的未來，

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

那時，我們可以把人類送到 比火星更遠許多的地方，

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

在那些地方，等待來自 地球的訊號來做導航，

is just not realistic.

是很不切實際的做法。

Imagine in this scenario that we can have a constellation,

想像一下，在這個情境中， 我們有一群衛星，

a network of communication satellites scattered throughout deep space

一個通訊衛星網路， 散佈在深太空各處，

broadcasting navigation signals,

廣播出導航訊號，

and any spacecraft picking up that signal

任何收到該訊號的太空船

can travel from destination to destination to destination

都能從一個目的地 前往另一個目的地，

with no direct tie to the Earth at all.

完全不用和地球有直接的連結。

The ability to accurately measure time in deep space

在深太空中精確測量時間的能力

can forever change the way we navigate.

能夠永遠改變我們導航的方式。

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

但，它也有可能可以 帶給我們一些很酷的科學。

You see, that same signal that we use for navigation

我們用來做導航的訊號

tells us something about where it came from

能告訴我們一些資訊， 包括它從何而來，

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

及它從天線到天線所經過的旅程。

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

關於那旅程的資料就能 用來建立更好的模型，

better models of planetary atmospheres throughout our solar system.

把整個太陽系的 行星大氣模型做得更好。

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

我們可以偵測到結冰的遙遠衛星上 有沒有任何表面下的海洋，

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

也許甚至可以偵測到相對論引力 在太空中所造成的小漣漪。

Onboard autonomous navigation means we can support more spacecraft,

若有機上自動導航， 就表示我們能支援更多太空船，

more sensors to explore the universe,

更多感測器，來探索宇宙，

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

也能讓像我這樣的導航員 能騰出時間來，

to work on finding the answers to other questions.

去努力找出其他問題的答案。

And we still have a lot of questions to answer.

還有很多問題等著被解決。

We know such precious little about this universe around us.

我們對宇宙的了解很少。

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

近年來，我們在我們的太陽系之外

發現了近三千個行星系統，

outside of our own solar system,

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

那些系統是近四千個系外行星的家。

To put that number in context for you:

幫助各位對這個數字有點概念：

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

我小時候初次學到行星時，

there were nine,

有九大行星，

or eight if you didn't count Pluto.

冥王星不算的話只有八個。

But now there are 4,000.

但，現在有四千個。

It is estimated that dark matter

據估計，我們的宇宙

makes up about 96 percent of our universe,

有 96% 是由暗物質組成，

and we don't even know what it is.

而我們甚至還不知道它是什麼。

All of the science returned

把我們所有深太空任務

from all of our deep space missions combined

所帶回來的科學知識加在一起，

is just this single drop of knowledge

也不過是浩瀚的問題大海中的

in a vast ocean of questions.

一滴水而已。

And if we want to learn more,

如果我們想要學習更多、

to discover more, to understand more,

發現更多、了解更多，

then we need to explore more.

我們就需要探索更多。

The ability to accurately keep time in deep space

在深太空中精確知道時間的能力

will revolutionize the way that we can explore this universe,

將會為我們探索 宇宙的方式帶來革命，

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

它很可能就是解開一些

宇宙珍貴秘密的關鍵之一。

that she holds so dear.

Thank you.

謝謝。

(Applause)

（掌聲）