Why extremophiles bode well for life beyond Earth - Louisa Preston

为什么嗜极生物可能适应外星生活？— Louisa Preston编制

翻译人员: Ying Minako Zhao 校对人员: Zhiting Chen

We've all seen movies

我们时常在电影里看到

about terrible insects from outer space

从外太空来的可怕的昆虫

or stories of abduction by little green men,

或者地球人被小绿人绑架的故事

but the study of life in the universe,

但是有关宇宙生物的研究

including the possibility of extraterrestrial life,

包括外星生物存在的可能性

is also a serious, scientific pursuit.

却是一门严肃的科学研究

Astrobiology draws on diverse fields,

天体生物学集合了

such as physics,

物理学

biology,

生物学

astronomy,

天文学

and geology,

以及地质学的知识

to study how life was formed on Earth,

来研究生命是怎样在地球上形成的

how it could form elsewhere,

它如何能在地球以外的地方形成

and how we might detect it.

以及我们怎样才能探知地外生命

Many ancient religions described

很多古老的宗教都描述过

other worlds inhabited by known human beings,

人类居住的另外的世界

but these are more like mythical realms

但这些都属于神话，

or parallel universes

或者是平行宇宙的范围

than other planets existing

与其它存在于

in the same physical world.

我们这个物理世界的行星无关

It is only within the last century

从上个世纪开始

that scientists have been able

科学家们才有能力

to seriously undertake the search

真正地着手

for extraterrestrial life.

有关地外生命的研究

We know that at the most basic level

我知道地球上最基本的生物需要三种物质：

organisms on Earth need three things:

我知道地球上最基本的生物需要三种物质：

liquid water,

液态水

a source of energy,

能量源

and organic, carbon-based material.

以及有机碳化物

We also know that the Earth

我们也知道地球

is just the right distance from the Sun,

与太阳之间的距离刚好

so as not to be either frozen or molten.

以至于我们不会被冰封，也不会被融化

So, planets within such a habitable range

所以，与恒星保持适当距离的行星

from their own stars

所以，与恒星保持适当距离的行星

may be able to support life.

应该有孕育生命的可能性

But while we used to think

我们曾经以为

that life could only exist

生命只能存在于

in such Earth-like environments,

类似地球的环境下

one of the most amazing discoveries of astrobiology

但是，天体生物学的最惊人的发现之一

has been just how versatile life is.

让我们知道了生命形式的多样性

We now know that life can thrive

我们现在知道

in some of the most extreme environments

生命可以在一些极其严酷的环境中成长

that'd be fatal for most known organisms.

而这些环境对大多数已知生物来说都是致命的

Life is found everywhere,

到处都可以找到生命的迹象

from black smoke of hydrothermal vents

从地球深海

in the dark depths of Earth's oceans,

热泉的黑烟

to bubbling, hot, acidic springs

到火山侧翼

on the flanks of volcanoes,

滚烫的酸性温泉

to high up in the atmosphere.

再到大气的高层

Organisms that live in these challenging environments

生长于这些环境中的生物

are called extremophiles,

被叫做嗜极生物

and they can survive at extremes

它们可以存活于极端的

of temperature,

温度

pressure,

压力

and radiation,

辐射

as well as salinity,

盐度

acidity,

酸度

and limited availability of sunlight,

以及有限的阳光

water,

水分

or oxygen.

或氧气

What is most remarkable about these extremophiles

这些嗜极生物最引人注目的是

is that they are found thriving in environments

适合它们生长的环境

that mimic those on alien worlds.

往往与外星环境相似

One of the most important of these worlds

最重要的地外行星之一

is our red and dusty neighbor, Mars.

是我们布满尘土的邻居，火星

Today, astrobiologists are exploring places

目前，天体生物学家们 正在利用美国宇航局（NASA）的

where life might once have existed on Mars

好奇号（Curiosity）火星探测器来勘探

using NASA's Curiosity rover.

火星上可能存在过生命的地方

One of these is Gale Crater,

其中一处便是盖尔撞击坑

an impact crater created

它是于将近38亿年前

when a meteor hit the surface of Mars

彗星撞击火星表面造成的

nearly 3.8 billions years ago.

彗星撞击火星表面造成的

Evidence from orbit suggest past traces of water,

我们从彗星轨道上发现有少量水分的迹象

which means the crater

说明撞击坑

might once have supported life.

可能曾经有过生命存在

Planets are not the only places

而天体生物学家们

astrobiologists are looking at.

不仅仅关注地外行星

For example, Europa, one of the moons of Jupiter,

它们也关注其它有可能存在生命的地方，包括

and Enceladus and Titan,

木星的卫星之一，木卫二

two of Saturn's moons,

以及土星的两个卫星

are all exciting possibilities.

土卫二和土卫六

Although these moons are extremely cold

虽然这些卫星都极其寒冷

and two are covered in thick ice,

其中两个还被厚冰覆盖

there is evidence of liquid oceans beneath the shell.

有证据表明它们的外壳下面存在液态海洋

Could life be floating around in these oceans,

生命有可能浮游在这些海洋中吗？

or could it be living around black smoker

或是生存于深海热泉的黑烟中？

vents at the bottom?

或是生存于深海热泉的黑烟中？

Titan is particularly promising

土卫六是很有希望的

as it has an atmosphere

因为它拥有大气层

and Earth-like lakes, seas, and rivers

并且其表面上分布着

flowing across the surface.

类似地球的湖泊，海洋，河流

It is very cold, however,

但是，它非常寒冷

too cold for liquid water,

以至没有液态水存在

so these rivers may instead be flowing

所以土卫六的河流中流动的应该是

with liquid hydrocarbons

液态的碳氢化合物

such as methane and ethane.

例如，甲烷和乙烷

These are composed of hydrogen,

这些物质由氢

and, more importantly, carbon,

和碳构成

which is the basic building block

而碳元素则是

of all life as we know it.

所有已知生命的基础组成部分

So, could life be found in these lakes?

那么，我们有可能在这些湖泊中发现生命吗？

Although instruments are being designed

虽然科学家们已经着手设计

to study these distant worlds,

用于探测遥远星球的仪器

it takes many years to build them

但是制造这些仪器需要许多年

and even longer to get them

而把它们送到外星

where they need to be.

则需要更长时间

In the meantime, astrobiologists work

在此期间，天体生物学家们将利用

in our own natural laboratory, the Earth,

我们的天然实验室，地球

to learn about all the weird

来了解可能存在的

and wonderful forms of life that can exist

各种奇特的生命形式

and to help us one day answer

从而帮助我们回答

one of humanity's oldest questions:

人类有史以来最古老的问题之一

Are we alone?

我们是孤独的吗？