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

翻译人员: Shu Fei Chow 校对人员: Yolanda Zhang

Picture a world with a variety of landforms.

想象一颗有着各式各样地貌的星球。

It has a dense atmosphere

它有着高密度的大气层，

within which winds sweep across its surface

地表还有

and rain falls.

大风和降雨。

It has mountains and plains,

它有山丘和平原、

rivers, lakes and seas,

河流、湖泊和海洋，

sand dunes and some impact craters.

沙丘以及一些撞击坑。

Sounds like Earth, right?

听起来很像地球，对吧？

This is Titan.

这是泰坦（“土卫六”）。

In August 1981,

在 1981 年 8 月，

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

旅行者 2 号拍下了 这颗土星最大卫星的影像。

The Voyager missions have traveled farther than ever before,

“旅行者”号的航行距离 比以往任何时候都要远，

making the solar system and beyond

将太阳系以外更遥远的地方

part of our geography.

也纳入了我们的地理观测范围。

But this image, this hazy moon

但这张图像，这颗朦胧的“月亮”，

was a stark reminder of just how much mystery remained.

时刻提醒着我们， 仍有许多未知需要去探索。

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

当旅行者飞过它时，为我们提供了 关于这颗星球的海量信息，

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

然而我们仍无从得知 它笼罩在大气层下的真实面貌。

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

它是否像我们观测到的 土星和木星的其他卫星那样，

that had been observed at Saturn and Jupiter?

具有表面由冰层覆盖的相似地貌呢？

Or perhaps simply a vast global ocean of liquid methane?

或者只有一片液态甲烷的汪洋大海 覆盖了整个表面？

Shrouded by the obscuring haze,

笼罩在阴霾下的泰坦

Titan's surface was a huge, outstanding mystery

是个巨大的谜团。

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

因而卡西尼－惠更斯号（Cassini-Huygens）， 这台于 1997 年发射的轨道着陆器，

was designed to solve.

为的就是要解开这个谜团。

After arrival in 2004,

在 2004 年抵达泰坦后，

the early images Cassini sent back of Titan's surface

卡西尼号最初传回的泰坦表面影像

only heightened the allure.

更是加深了人们对它的好奇。

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

我们耗费了数月的时间才弄清楚

to determine, for example,

我们在火星表面看到的是什么，

that the dark stripes,

比如，那些我们一开始认不出来，

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

因而被称为“猫抓痕”的深色的条纹，

were actually dunes made of organic sand.

实际上是由有机沙土构成的沙丘。

Over the course of the 13 years Cassini spent studying Saturn

在卡西尼号研究土星、 土星环和其卫星的

and its rings and moons,

十三年里，

we had the privilege

我们幸运的

of going from knowing almost nothing about the surface of Titan

从对泰坦的表面一无所知，

to understanding its geology,

到逐渐开始了解它的地理构造，

the role the atmosphere plays in shaping its surface,

以及大气层对其表面地形的影响，

and even hints of what lies deep beneath that surface.

甚至对其地底深处的探索 也有了些眉目。

Indeed, Titan is one of several ocean worlds,

事实上，泰坦是若干个

moons in the cold outer solar system

位于冰冷的外太阳系、

beyond the orbits of Mars and the asteroid belt

火星轨道和小行星带之外，

with immense liquid water oceans beneath their surfaces.

表面下覆盖着 大面积液态水的卫星之一。

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

泰坦内部海洋的含水量可能是

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

地球上所有河流、湖泊 和海洋体积总和的 10 倍以上，

And at Titan, there are also exotic lakes and seas

同时，其表面也覆盖着 由液态甲烷和乙烷构成的

of liquid methane and ethane on the surface.

奇异湖泊和海洋。

Ocean worlds are some of the most fascinating places

海洋世界是太阳系中

in the solar system,

最迷人的地方，

and we have only just begun to explore them.

然而我们对它们的探索才刚刚启程。

This is Dragonfly.

这是“蜻蜓号”，

At the Johns Hopkins Applied Physics Laboratory,

是我们在约翰霍·普金斯大学的 应用物理实验室

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

为美国国家航空航天局 新疆界计划而打造的。

Scheduled to launch in 2026 and reach Titan in 2034,

“蜻蜓号”预计将在 2026 年发射， 并于 2034 年抵达泰坦。

Dragonfly is a rotorcraft lander,

它是一个旋翼机着陆器，

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

其体积与火星探测车 或小型汽车相近。

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

“蜻蜓号”的设计主要考量了

make it a great place to fly,

泰坦稠密的大气层和低重力因素，

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

使得“蜻蜓号”非常适合 在这样的环境内执行飞行任务。

Technically an octocopter,

“蜻蜓号”实际上是个八旋翼飞机，

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

也是个移动实验室，

taking all of its scientific instruments with it.

能随身携带科学仪器到处飞行。

Dragonfly will investigate Titan in a truly unique way,

“蜻蜓号”将以非常独特的方式 考察泰坦，

studying details of its weather and geology,

包括它的气候环境和地理构造，

and even picking up samples from the surface

甚至直接从地表采集样本，

to learn what they're made of.

以此了解它们的成分。

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

换言之，“蜻蜓号” 将耗费三年时间探索泰坦，

measuring its detailed chemistry,

分析它具体的化学成分，

observing the atmosphere and how it interacts with the surface,

观察大气层是如何 与地表产生作用，

and even listening for earthquakes,

甚至聆听地壳的震动，

or technically titanquakes, in Titan's crust.

或者叫“泰坦震”。

The Dragonfly team,

“蜻蜓号”在北美和世界各地

hundreds of people across North America and around the world,

数百人的研究团队

is hard at work on the design for this mission,

都为这个任务的设计 付出了很多心血——

developing the rotorcraft, its autonomous navigation system

研发旋翼飞行器、 自主导航系统

and its instrumentation,

及各种仪器。

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

所有这些部分都需相互配合，

on the surface of Titan.

以完成泰坦表面的科学测量任务。

Dragonfly is the next step in our exploration

“蜻蜓号”的内部实验室

of this fascinating natural laboratory.

是引导我们探索泰坦的下一步。

In flying by, Voyager hinted at the possibilities.

旅行者在飞行时 揭示了各种可能性。

In orbiting Saturn for over a decade

环绕土星运行十多年，

and descending through Titan's atmosphere,

并穿过了泰坦的大气层后，

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

卡西尼-惠更斯号 进一步揭开了泰坦的神秘面纱。

Dragonfly will live in the Titan environment,

“蜻蜓号”将会继续考察泰坦，

where, so far, our only close-up view

而截至目前，我们获得的 唯一一张泰坦的近距离照片，

is this image the Huygens probe took in January 2005.

还是惠更斯号 在 2005 年 1 月所拍摄的这张。

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

在很多方面，泰坦都是我们已知的

the Earth before life developed here.

与生命出现之前的地球 最相似的星体。

From Cassini-Huygens' measurements,

从卡西尼-惠更斯号的 测量结果来看，

we know that the ingredients for life,

我们知道生命的组成部分——

at least life as we know it,

至少是我们所了解的生命——

have existed on Titan,

早已在泰坦上出现过，

and Dragonfly will be fully immersed within this alien environment,

而“蜻蜓号”将会完全沉浸在 这个陌生的环境中，

looking for compounds similar to those

寻找那些与可能促成了 地球上生命发展的化学成分

that might have supported the development of life here on Earth

相似的化合物，

and teaching us about the habitability of other worlds.

并协助我们探索其他世界的宜居性。

Habitability is a fascinating concept.

宜居性是个令人着迷的概念。

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

什么样的条件 使得一个环境适合孕育生命——

whether life as we know it here on Earth,

无论是我们已知的地球生命，

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

还是在不同情况下 衍生的另类生命？

The possibility of life elsewhere

其他星球存在生命的可能性

has inspired human imagination and exploration throughout history.

在历史上激发了人类的想象 和对太空的探索。

On a grand scale,

在宏观的尺度上，

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

这就是为何外太阳系的海洋世界

have become such important targets for study.

会成为如此重要的研究对象。

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

是人类的好奇心 在推动着前所未有的探索。

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

我们不知道化学物质 如何在地球上演变成生物，

but similar chemical processes may have happened on Titan,

但类似的化学过程 可能也发生在泰坦上，

where organic molecules have had the opportunity

因为那里的有机分子

to mix with liquid water at the surface.

有机会与其表面的液态水混合。

Has organic synthesis progressed under these conditions?

有机合成反应在这些条件下 是否催生了化学反应？

And if so, how far?

如果是的话， 究竟到了何种程度？

We don't know ... yet.

目前，我们还无从得知。

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

我们通过“蜻蜓号”所见证的 人类的不懈努力

is tantalizing.

是很振奋人心的。

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

这是对生命的基础架构 和化学步骤的探索，

like those that ultimately led to life on Earth.

正如那些最终为地球 带来了生命的过程一样。

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

我们不确定会在泰坦上 发掘到什么，

but that's exactly why we're going.

但这也正是我们 要前往那里的原因。

In 1994, Carl Sagan wrote,

1994 年，卡尔·萨根（Carl Sagan ）写道：

"On Titan, the molecules that have been raining down

“在泰坦上，过去 40 亿年来

like manna from heaven for the last four billion years

像神赐的甘露一样 从天而降的分子

might still be there,

至今可能还在那里，

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

保持着冻结状态下的原貌， 等待着地球化学家的到来。”

We are those chemists.

我们就是那些化学家。

Dragonfly is a search for greater understanding,

“蜻蜓号”的任务

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

不仅能帮助我们掀开 泰坦和太阳系的神秘面纱，

but of our own origins.

还能解开地球起源的奥秘。

Thank you.

谢谢。