What Saturn's most mysterious moon could teach us about the origins of life | Elizabeth Turtle

譯者: Amanda Zhu 審譯者: Helen Chang

Picture a world with a variety of landforms.

想像一個地形多樣的世界。

It has a dense atmosphere

它有一個高密度的大氣層，

within which winds sweep across its surface

有風席捲表面和降雨。

and rain falls.

It has mountains and plains,

它有高山、平原、河流、湖泊和海洋，

rivers, lakes and seas,

sand dunes and some impact craters.

也有沙丘和一些隕石坑。

Sounds like Earth, right?

聽起來很像地球， 對吧?

This is Titan.

這是泰坦。

In August 1981,

1981 年 8 月，

Voyager 2 captured this image of Saturn's largest moon.

航海家二號拍攝了這張 土星最大衛星的影像。

The Voyager missions have traveled farther than ever before,

航海家的任務走得比以往更遠，

making the solar system and beyond

將太陽系和更遠的地方

part of our geography.

都畫到我們的地圖上。

But this image, this hazy moon

但是這個影像，這個朦朧的月亮，

was a stark reminder of just how much mystery remained.

點醒了我們它仍有許多神秘與未知。

We learned an exponential amount as the Voyagers flew by it,

當旅行者飛過它時， 我們對它的瞭解突然大增，

and yet we had no idea what lay beneath this atmospheric blanket.

但我們仍不知道 籠罩在這大氣之下的面貌。

Was there an icy surface with landforms like those of the other moons

它是否像觀測到的 其他土星和木星的衛星，

that had been observed at Saturn and Jupiter?

表面結冰或有相似的地貌，

Or perhaps simply a vast global ocean of liquid methane?

或只是一片液態甲烷的汪洋 覆蓋整個表面？

Shrouded by the obscuring haze,

被籠罩在陰霾下的泰坦表面 是個巨大的謎團。

Titan's surface was a huge, outstanding mystery

that Cassini-Huygens, an orbiter lander pair launched in 1997,

卡西尼－惠更斯號 這對繞行土星和登陸泰坦的搭檔

於 1997 年發射，

was designed to solve.

任務就是要解開這個謎團。

After arrival in 2004,

它們在 2004 年到達後，

the early images Cassini sent back of Titan's surface

卡西尼號最初傳回的泰坦表面影像

only heightened the allure.

更加深了它的魅力。

It took months for us to understand what we were seeing on the surface,

我們花了幾個月時間才明白 在泰坦表面上我們看到的到底是什麼；

to determine, for example,

例如我們稱為貓爪痕的

that the dark stripes,

which were initially so unrecognizable that we referred to them as cat scratches,

那些剛開始無法分辨的深色條紋，

were actually dunes made of organic sand.

其實是有機沙堆成的沙丘。

Over the course of the 13 years Cassini spent studying Saturn

在卡西尼號研究土星、 土星環和其衛星的十三年中，

and its rings and moons,

we had the privilege

我們有幸從對泰坦表面幾乎一無所知

of going from knowing almost nothing about the surface of Titan

to understanding its geology,

到瞭解它的地質

the role the atmosphere plays in shaping its surface,

以及它的大氣對表面地形的影響，

and even hints of what lies deep beneath that surface.

甚至在泰坦地底深處 是什麼也有些線索。

Indeed, Titan is one of several ocean worlds,

事實上，泰坦是幾個 太陽系的海洋世界之一。

moons in the cold outer solar system

這些海洋世界都是 火星軌道和小行星帶之外

beyond the orbits of Mars and the asteroid belt

寒冷的外太陽系中的衛星。

with immense liquid water oceans beneath their surfaces.

它們的表面下是液態水的海洋。

Titan's interior ocean may have more than 10 times as much liquid water

泰坦地下海洋的水

可能是地球上所有河流、湖泊、海洋 全部水量的 10 倍以上。

as all of the Earth's rivers, lakes, seas and oceans combined.

And at Titan, there are also exotic lakes and seas

泰坦表面還有不尋常的湖泊和海洋，

of liquid methane and ethane on the surface.

裡面都是液態甲烷和乙烷。

Ocean worlds are some of the most fascinating places

海洋世界是太陽系中 最迷人的一些地方，

in the solar system,

and we have only just begun to explore them.

我們才剛開始探索它們。

This is Dragonfly.

這是蜻蜓號。

At the Johns Hopkins Applied Physics Laboratory,

在約翰霍普金斯應用物理實驗室裡，

we're building this mission for NASA's new Frontiers program.

我們正在為美國太空總署的 新疆界計劃打造這個任務。

Scheduled to launch in 2026 and reach Titan in 2034,

蜻蜓號計劃於 2026 年發射， 2034 年到達泰坦。

Dragonfly is a rotorcraft lander,

它是一個旋翼登陸艇，

similar in size to the Mars rovers or about the size of a small car.

大小與火星探測車或小型汽車相近。

Titan's dense atmosphere, combined with its low gravity,

泰坦高密度的大氣層，加上低重力，

make it a great place to fly,

使它成為很適合飛行的地方。

and that's exactly what Dragonfly is designed to do.

蜻蜓號的設計就是要 能在泰坦大氣中飛行。

Technically an octocopter,

蜻蜓號實際上是一個八旋翼飛行器，

Dragonfly is a mobile laboratory that can fly from place to place

裡面是個行動實驗室，

可以帶著它所有的科學儀器飛來飛去。

taking all of its scientific instruments with it.

Dragonfly will investigate Titan in a truly unique way,

蜻蜓號將以非常獨特的方式調查泰坦，

studying details of its weather and geology,

仔細研究它的氣候和地質，

and even picking up samples from the surface

甚至從表面採集樣本，

to learn what they're made of.

瞭解它們的組成。

All told, Dragonfly will spend about three years exploring Titan,

總之，蜻蜓號將花費 大約三年時間探索泰坦，

measuring its detailed chemistry,

仔細測試它的化學成分，

observing the atmosphere and how it interacts with the surface,

觀察大氣層及其如何與地表相互作用，

and even listening for earthquakes,

甚至聆聽泰坦地殼中的地震，

or technically titanquakes, in Titan's crust.

或應該說是「泰坦震」。

The Dragonfly team,

蜻蜓號團隊在北美 和世界各地有數百人，

hundreds of people across North America and around the world,

is hard at work on the design for this mission,

他們正在努力設計這次任務，

developing the rotorcraft, its autonomous navigation system

開發旋翼飛行器、 自主導航系統及各種儀器，

and its instrumentation,

all of which will need to work together to make science measurements

這些東西都需要互相配合， 以達成在泰坦表面進行科學測量的任務。

on the surface of Titan.

Dragonfly is the next step in our exploration

蜻蜓號是我們探索這個 迷人的自然實驗室的下一步。

of this fascinating natural laboratory.

In flying by, Voyager hinted at the possibilities.

航海家在飛過時，暗示了各種可能性。

In orbiting Saturn for over a decade

卡西尼環繞土星運行十多年

and descending through Titan's atmosphere,

和惠更斯穿過泰坦大氣層後，

Cassini and Huygens pulled Titan's veil back a bit further.

泰坦的面紗又多拉開了一點。

Dragonfly will live in the Titan environment,

蜻蜓號將生活在泰坦環境中。

where, so far, our only close-up view

到目前為止，我們唯一的泰坦特寫照片

is this image the Huygens probe took in January 2005.

是惠更斯探測器在 2005 年 1 月拍的。

In many ways, Titan is the closest known analogue we have to the early Earth,

在許多方面，泰坦是我們已知星體中

the Earth before life developed here.

和早期還沒有生物的地球 最相似的一個。

From Cassini-Huygens' measurements,

從卡西尼－惠更斯的測量中，

we know that the ingredients for life,

我們知道生命組成成分

at least life as we know it,

——至少是我們知道的 生命組成成分——

have existed on Titan,

已經存在於泰坦上，

and Dragonfly will be fully immersed within this alien environment,

而蜻蜓號將完全沉浸在 這個外星環境中，

looking for compounds similar to those

尋找類似於那些可能支持 地球上生命發展的化合物，

that might have supported the development of life here on Earth

and teaching us about the habitability of other worlds.

並讓我們瞭解其他世界的適居性。

Habitability is a fascinating concept.

適居性是個吸引人的概念。

What's necessary to make an environment suitable to host life,

是什麼使一個環境適合孕育生命？

whether life as we know it here on Earth,

無論是我們已知的地球生命，

or perhaps exotic life that has developed under very different conditions?

或是在非常不同的條件下 發展出的異星生命。

The possibility of life elsewhere

外星生命存在的可能性

has inspired human imagination and exploration throughout history.

在歷史上激發了人類的想像力和探索。

On a grand scale,

放大規模來看，

it's why the ocean worlds in the outer solar system

這就是外太陽系的海洋世界

成為如此重要的研究標的的原因。

have become such important targets for study.

It's the "what if" that drives human exploration.

「如果」推動著人類的探索。

We don't know how chemistry took the step to biology here on Earth,

我們不知道化學物質 如何在地球上演變成生物，

but similar chemical processes may have happened on Titan,

但類似的化學過程 可能曾發生在泰坦上，

where organic molecules have had the opportunity

因為那裡的有機分子 有機會與液態水混合。

to mix with liquid water at the surface.

Has organic synthesis progressed under these conditions?

有機合成反應在這些條件下有進展嗎？

And if so, how far?

如果是，到了甚麼程度？

We don't know ... yet.

我們……

還不知道。

What we will learn from Dragonfly, this fundamentally human endeavor,

未來我們從蜻蜓號學到的東西， 這種人類根本的努力，

is tantalizing.

是很誘人的。

It's a search for building blocks, foundations, chemical steps

它在尋找的是地球 在演變出生命的過程中，

一步一步累積的一磚一瓦、 地基和化學反應。

like those that ultimately led to life on Earth.

We're not sure exactly what we will find when we get to Titan,

我們不確定到達泰坦時， 我們會找到什麼，

but that's exactly why we're going.

但這正是我們要去的原因。

In 1994, Carl Sagan wrote,

1994 年，卡爾·薩根寫道：

"On Titan, the molecules that have been raining down

「在泰坦上，過去 40 億年來

like manna from heaven for the last four billion years

像神賜嗎哪一樣 從天而降的分子可能還在那裡，

might still be there,

沒什麼改變，

largely unaltered, deep-frozen, awaiting the chemists from Earth."

深凍著，等待來自地球的化學家。

We are those chemists.

我們就是那些化學家。

Dragonfly is a search for greater understanding,

蜻蜓號的任務不僅是幫我們 了解泰坦和我們太陽系的奧秘，

not just of Titan and the mysteries of our solar system,

but of our own origins.

更是要尋找我們自己的起源。

Thank you.

謝謝。