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火星上有生命吗?

Is There Life on Mars? | Space Time

《PBS数码工作室》
火星上曾经存在过生命吗?
Has there ever been life on Mars?
没有 可能是没有吧
No. Probably not.
也可能有?我不是很确定
Maybe? I don’t know.
在我们对火星生命的探索中 没有什么
There is no greater hero in our search for life on Mars
比这个叫做“机遇号”的小机器人贡献更大了
than a little robot named Opportunity.
它在火星服役了15年
15 years after it’s mission began
超过它的预计任务时长57倍
57 times longer than it is signed up for
“机遇号”现在已经停止工作
Opportunity has gone silence.
在我们等待期盼NASA和“机遇号”重建通讯时
As we wait and hope on NASA raises to reestablish contact.
我们认为我们应该深思
We thought we would reflect on the greater quest
“机遇号”对探索火星生命
for the Opportunity has contributed so much to
所做出的巨大贡献
the search for life on Mars.
火星 一颗红色的星球 太阳的第四颗行星
Mars, the red planet fourth from the sun
最近刚好经过近地点 在傍晚的夜空中
it’s currently just passed its closest approach to Earth
它看起来就像一粒红色的烙铁
making it an angry red irony in early night sky
就我们目前所知 火星是一颗
This is a planet that as far as we know
只有机器人存在的星球
is inhabited entirely by robots
但在七月末 一些惊人发现的公布
but at the end of the July, something remarkable was announced
或许可以证明火星上生命存在的可能性
may prove the possibility of life on Mars
如今 在火星南极的地下存在着
There is a giant underground lake of liquid water
一个有液态水的巨型地下湖泊
right now, under the south pole
随着ESA和NASA发射任务的进行
and in 2020 the race to find life on Mars will intensify
到2020年 火星上寻找生命的竞赛将更加激烈
with both ESA and NASA launching missions
因为现在我们已知火星上有水存在
They will shift the focus from the search for water
他们将会把重点从寻找火星上的水
because we now know there is water
转变成寻找火星上过去或现存的生命
to the search for life, past or present.
NASA也正计划着取一份火星土的样本
NASA’s also planning a mission to take a sample of Martian soil
并将它载回地球
and rocket it back to Earth.
采用地球上最好的科学技术
Applying our best earth bound technologies
对这份未经污染的样本进行分析
to an uncontaminated sample
就像我们一直希望的那样
may provide the proof of Martian life
这或许可以提供火星生命存在的证据
we’ve always been hoping for.
但是作为一名优秀的科学家 我们必须保持严谨
But as a good scientist, we have to suggest in caution
因为人们一直都在寻找火星上的生命
because people have been searching for life on Mars
并且坚信他们在300多年前就已经发现了
and believing they found it for over 300 years.
所以今天我们不得不回顾一下火星生命的漫长历史
So today, we have to look back at the long history of life on Mars
或者至少可以说是我们寻找火星生命的历史
or at least of our hunt for it.
这段历史开始于17世纪末
We begin our story at the end of the 17th century,
当时荷兰博学家克里斯蒂安·惠更斯
when Duch polymath Christiaan Huygens
对伽利略宇宙望远镜进行了令人惊叹的改进
made amazing advances on Galileo astronautical telescope,
这使他观察到了火星表面的一块黑斑
this let him to observe a dark patch on the Martian surface
据此他测量出火星的自转周期为24小时
and so measured Mars as 24-hour rotation rate,
同时他也观察到了火星南极区域的一个白点
as well as a white spot on it’s south pole
他猜测
He guessed
二者均是由地表水 云和冰产生的
that both of these resulted from surface water, clouds and ice
惠更斯将这视为
Huygens saw this as evidence
火星适合生物居住
that Mars was habitable
并且可能已经有生物居住的证据
and so perhaps inhabited.
事实上他是第一个
In fact he was the first postulated
假定液态水是生命必需品的人
that liquid water is necessary for life
经过几个世纪的探索只不过使我们进一步相信了这个结论
A few centuries of exercise has only convinced us further of this
正如我们之前讨论的一样
As we discussed before
惠更斯在很多方面都很有预见性
Huygens was a visionary in many ways
但是他对火星观察的解读只对了一半
But only half right in his interpretations of his observations of Mars
白点确实是极地冰盖
The white spot was indeed a polar ice cap
但是黑点应该是
But the dark spot was probably
大瑟提斯高原的火山岩
the volcanic rock of the Syrtis Major Planum
尽管如此 火星有水存在的预期
Nonetheless the prospect of a watery Mars
引起了人们数百年来的
kicked off centuries of optimism
邻近行星适宜生存的乐观猜想
for inhabitant planetary neighborhood
宇航员杰克·默紧随惠更斯之后
Astronomer Jackmo Moriaty quickly followed Huygens
在十八世纪早期 于火星两极发现的冰盖
And in the early 18th century discovered ice caps on both poles
正确地推断了火星的自然规律
correctly inferring the nature
18世纪后期 威廉·赫歇尔
Later that century, William Herschel
观测到冰盖每年的增减
watch the Ice Caps grow and shrink annually
他认为这是一个他称之为舒适而又温和的环境
and thought he saw what he calls a comfortable but modest atmosphere
赫歇尔总体上认为火星
Herschel generously decreed of Mars that
生存环境各个方面都和我们很相似
its inhabitant probably enjoy a situation in many respects similar to ours
现在 赫歇尔还是一名了不起的天文学家
Now, Herschel was a fantastic astronomer
但是他火星大气的错误推断给了我们一个很好的反例
But his wrongness about Mars atmosphere is a nice example
即使是最聪明的人 也会只看到他想看的
That even the smartest of us see what we want to see
作为一名科学家 应该要对那种个人偏见保持警惕
As a scientist, it’s so important to stay aware of that very human bias
因为这导致了多数情况下
Because it’s led to the erroneous discovery of life on Mars
火星上生命的错误发现
on multiple occasions.
早在1877年
Fast forward to 1877
乔瓦尼·斯基亚帕雷利便致力于研究
Giovanni Schiaparelli was studying Mars
处于近日点的火星
during its perihelion opposition
这种行星排位最近也刚出现过
That is the configuration that also just passed recently
火星经过距离太阳最近的点
Mars was at its closet approach to the sun
同时也是距地球最近的点
And the earth at its closest to Mars
他在火星表面观测到了一些条纹
he observed streaks on the surface of planet
并将其命名为“Canali”
That he named Canali
在意大利语中意为“水道”
That is Italian for channels
这应该是在暗示自然形成的水流
Presumably implying naturally formed flows of water
某种程度上它和新建的苏伊士运河相似
Perhaps in part with the newly made Suez Canal
对于人们来说仍然很新奇
still fresh on people’s minds,
“Canali”被错译成英文中的运河
Canali was mistranslated into English to canals
意味着这是人工开凿的
Implying artificially made structures
人们只能看到自己想看到的
people see what they want to see
并且听到自己想听到的
And they hear what they want to hear
这种火星上可能有科技文明的预测
The prospect of a technological civilizations on Mars
鼓舞着商人去成为天文学家
inspired businessesman to astronomer
帕西瓦尔·罗威尔
Percival Lowell
他自已建造了一个天文台
He build himself an observatory
并且致力于火星研究
And dedicated his career to study Mars
罗威尔天文台因发现冥王星而著名
The Lowell observatory is famous for discovery a Pluto
但这是后来的事情了
But that was later
罗威尔痴迷于火星运河
Lowell was obsessed with the Martian canals
他花了15年绘制了火星的表面图
He spent 15 years making certificate drawing of its surface
之后他就全力投身于研究古代火星人
Then he went full on “ancient Aliens” Martian edition
他相信火星运河是古代进步文明的遗迹
He believe that the canals was a relic of ancient advanced civilization
他们为了转移极地冰盖的水开凿了这些运河
They build them to move water from polar ICE CAPS
因为这是这个星球上最后的水源
as it is the last source of water on the drawing planet
罗威尔写了三本有关这个主题的书
Lowell wrote three books on the subject
最后一本呈现了火星生命的完整理论
The last presenting is full theory on the subject of life on Mars
这让火星存在生命的说法在大众里流行了起来
This popularized the belief in the general public of life on Mars
并涌现了一批科幻作品
Automatically inspiring works of fiction like
如赫伯特·乔治·威尔斯的《世界大战》
H.G.Wells, The War of the Worlds
以及雷·布莱伯利的《火星纪事》
or Ray Bradbury, The Martain Chronicles
事实证明罗威尔的运河只是虚构的
It turns out that Lowell’s canals were just as fictional
可能只是望远镜缺陷导致的光学现象
Probably a combination of artefacts from imperfect telescopic optics
和现实状况的结合产生的
Plus actual arrange features
我们需要通过去火星探索来确认运河的存在
We had to actually go to Mars to really confirm this
在20世纪六七十年代
In the 1960s and early 70s
“水手计划号”首次飞掠火星
The Mariner Missions conducted the first Mars flybys
向我们展示了这个星球的近貌
giving us a very first close up of the planet
“水手号”没有找到运河
Mariner didn’t find canals
但它确实找到了古代河床
But it did find evidence of ancient River Beds
蚀刻在土地上的证据
carve to the landscape
这个有关古代流水的证据
This evidence for ancient flowing water
在当时并没有说服力
wasn’t definitive at the time
我们需要更近的观察
A closer look was needed
1976年NASA发射的维京1和2号在火星表面登陆
NASA landed Viking Ⅰ and Ⅱ on the surface of Mars in 1976
他们做了四项实验来检测
They conducted four experiments looking for
过去或现存微生物的生物标志
the biosignature of past or present microbe life
前三项实验结果均呈现阴性
Three of the tests went negative
但第四项实验结果显示为阳性
But the fourth was positive
这项实验被称为标记释放实验
It was the so-called label released experiment
在这项实验中 一个土壤样本被注入
In it, a soil sample is fed nutrients
含有放射性碳-14的营养液
laced with radioactive carbon-14
任何微生物都会对营养液进行代谢
Any microbes should metabolise the nutrients
这样就会释放出具有放射性的二氧化碳
and it spilt radioactive CO2
很快 两个探头都检测到了这些放射性气体
Right away, both probes detected these radioactive gases
一个普遍的原则和真理是
A general rule and science is that
我们的实验结果只有可复验才能证明其可信
our result isn’t real until it is repeatable
这项实验在测试后一个星期失败了
And this experiment fail that test a week later
虽然一些人认为维京号最初的结果
While some thought the initial Viking results were
显示火星上存在着生物标志
a positive active biosignature on Mars
大多数人认为这个结论是站不住脚的
Most agreed the results were inconclusive
很可能是一些土壤中的非生物反应所造成的
likely results of some abiotic or non-living reaction in the soil
很可惜并不是火星上的微生物
And sadly not microscopic martains
1984年 人类在南极洲发现了
And then there is a famous Martian Fossil Meteorite
一块著名的火星化石陨石
This rock was discovered in Antarctica in 1984
基于它的化学成分 可以确定它来自火星表面
Based on its chemical composition, it must come from the surface of Mars
可能是火星和其他太空中的碎石相撞
Probably ejected from Mars gravitational field
溅射到地球上的陨石
after another space rocks mashed into the planet
这块化石已有40亿年的历史了
It was dated around 4 billion years old
从那时起我们一直相信
from the time when we now believe
火星表面有液态水
Mars had liquid water on the surface
这块岩石隐藏了这个秘密数以千万年
This rock held a tiny secert for all those billion of years
并又继续隐藏了数十年
and it will hold that secert for another decades still
直到1996年
into 1996
随着更高分辨率的
with the advent of higher resolution
扫描电镜以及激光质谱法的出现
scaning electron microscopy and laser mass spectrometry
分析结果显示有一种链结构
that analysis reveled a chain structures
与地球的微体化石十分相似
that look an awful look like earth’s microfossils
这一存在生命的直接证据
this direct detection of actual tryst of life
甚至让美国总统克林顿发出了公告
even prompted an anouncement from President Clinton
但这有可能又是一场虚惊
but once again it was probably a false alarm
就像维京号的测试结果一样
just like the Viking test results
这些现象也可以用非生物过程来解释
these features could be explained by non-biological processes
除非没有任何其他的解释 否则不可能是外星生物
it’s never aliens untill there is no other possible explanations
所有这些差之毫厘的失误都是有意义的
all of these near misses did serve the power for good
幸好有我们对这个红色星球的持续探索
thanks by our continued procession with red planet
以及担负着如此多的任务
and so many more missions followed
一系列轨道卫星 着陆器和漫游者
a serious of orbiters, landers and rovers
发现了越来越多的证据证明火星从古至今都有水的存在
found increasing evidence so past and present activity of water on Mars
“奥德赛”火星轨道卫星探测到了某些原子 比如氢
the Mars Odyssey Orbiter detected atoms like hydrogen
告诉我们有大量的水冰凝结于
that told us of enormous quantities of water ices
接近火星两极的土壤
froze into the Martian soil closed to the poles
接下来就说到了“机遇号”
and that brings us to Opportunity.
另外很少有人知道火星探测漫游者-B
Otherwise fractionally known as Mars Exploration Rover-B
和它的孪生兄弟探索者-A在2004年登陆
it landed in 2004 with its twin, MER-A,
比勇气号更出名
better known as Spirit.
这些高尔夫球车大小的六轮机器人
These six wheeled golf-cart-sized robots
是地质实验仪器中的瑞士军刀
were Swiss army knives of geological lab instruments.
机遇号最惊人的发现
Opportunity’s most spectacular discovery
是这些被称为“蓝莓”的小圆石
was these cute little so called berries.
结果发现它们是赤铁矿的凝结物
They turned out to be concretions of hematite
这意味着它们是在有溶解铁的潮湿环境中形成的
which means they were grown in wet environments with dissolved iron.
湿的意思是有水存在
Wet means water FYI.
两辆火星车都发现了
Both rovers found a variety of
古代水流活动产生的各种地质迹象
other geological signs of past water activity,
这更加确定了火星过去存在大量的水
really solidifying the picture of Mars was much more liquid past.
这两辆火星车大约在90天后会被关闭
Both rovers were supposed to shut down after around 90 days
因为火星上的灰尘会堆积在它们的太阳能电池板上
as Martian dust accumulated on their solar panels
阻断它们的电力供给
cutting of their power supply.
但出乎意料的是 火星上的风做了些清洁工作
But unexpected “cleaner” events from the Martian wind
清理掉了那些堆积物
clean those accumulations allowing
极大地延长了两辆火星车的服役时间
the massively extended life spans of both rovers
“勇气号”干的不错但是最终在关闭前陷入了沙坑
Spirit did great but eventually bogged in the sand trap before shutting down
而“机遇号”一直保持着工作
Opportunity just checked on and on and on
浩大的火星沙尘暴自六月初就席卷了这个星球
the vast Martian dust storm has developed the planet
导致了机遇号只能进入休眠模式
since early June caused Opportunity to enter hibernation mode
直到我们录这个视频的时候 风暴才开始平息
as we filming this video the storm is only starting to settle down
NASA以及我们所有人
NASA and all of us remain hopeful
仍然希望能重建通讯系统
the communication will be reestablished
但即使没能重建
but even if not
你也已经尽职了 勇敢的机遇号
you’ve earned your rest, brave Opportunity
“凤凰号”着陆器将会首先尝到火星水
the Phoenix lander was the first taste Martain water
同时在火星北极对冻土进行取样
sampling the icy soil in the northern polar region
其中“凤凰号”发现了大量高氯酸盐
It found an abundance of Perchlorate type of salt
这对于生命并不是一个好消息
that’s actually bad news for life.
高氯酸盐作为抗冻剂降低了水的凝固点
Perchlorate act as anti-freeze lowering the freezing point of water.
这在之后将起到重要作用
And this will be important later,
我们最近的火星漫游者“好奇号”
Our latest Martian explorer Curiosity rover,
在火星低纬度区域取样
it sampled soil at lower latitudes
证实了整个行星范围内的土壤都有水的存在
and comfirmd the presence of H2O in the soil planet wide.
这就是我们现在的状况
This brings us just about the presence
2018是一个证明火星生命存在可能性的伟大年度
2018 has been a great year for the possibility of life on Mars.
有两篇论文梦幻般在同一天发表
Two papers came out on the same dream day.
一篇表明了在火星大气中检测到了甲烷
One reported the detection of methane in atmosphere
所以我们发现有火星微生物放屁?
so have we seen Martian microbe farts?
有可能 但不一定
Maybe, but not necessarily
再强调一遍 非生物活动也能产生甲烷
again, there are non-biological processes that generate methane
第二篇论文是关于在火星表面的
the second paper was about organic molecules
泥岩中发现了有机分子
found in mudstone on the Martian surface
但是别忘了有机物在化学中
then remember organic in chemistry
只是一种含碳化合物
just means a compound containing carbon
我们在很多生命不可能存在的地方
We found small organic molecules
也发现了有机小分子
in lots of places that life is never touch
但是科学家认为这种火星上的分子
but the scientist think that this Martian molecules
源于一种叫做“油母岩质”的有机大分子
originated from large organic molecules called kerogens
它们往往在一种生物的衰变后产生
which are often produced in the decay of one’s living matter
当然也有另一些非生物的方法能产生它们
and of course, there are other non-biologic ways to produce them
但所有的这些悬念都让科学家非常振奋
but all of these teasers have gotten scientists very excited.
可能近期最棒的发现就是
Perhaps the coolest recent discovery is this giant underground lake
我在本集开头提到的巨型地下湖
I metioned at the start of the episode
在七月末
At the end of July,
欧空局宣告了这个地下湖的发现
the European Space Agency announced this lake was discovered
通过“火星快车号”携带的MARSIS探地雷达测得
using radar reflection from the MARSIS instrumet on the Mars Express orbiter
我们还用同样的方法
This is the same way we mark the ocean
即通过分析表面以下各层之间的反射波测量海洋
by analyzing radio waves reflected from layers below the surface
MARSIS雷达探测器发现了表层冰盖
and MARSIS Radar reviewed a boundary between the surface ice cap
和地表1.5千米下 超过20千米宽的液态水区域
and liquid water 1.5 kilometers below the surface
之间的分界面
and 20 kilometers wide area.
在凝固点以下几十度的区域
It’s odd to find liquid water in a region
发现液态水是非常奇怪的
that is showing several tens of degrees below freezing
但这可能就是那些高氯酸盐析出的原因
but this may be why those perchlorate come back
在足够的压力下
with enough of this stuff
水的凝固点甚至可以低至零下75摄氏度
the freezing point of water could be as low as -75℃.
所以这是一个酷寒的高浓度咸水湖
So it’s an intensely cold, intensely salty lake
甚至地球上最极端的有机体都难以生存
that even earth’s most highly extreme of organisms would have trouble with
但那也并非不可能
But it’s liked nonetheless
在火星冰盖上下钻1.5千米
it’s a simple matter of drilling 1.5 kilometers
进行勘探并不是什么大问题
into the martian ice cap to investigate.
对了!我有一个想法
Hey! Here is an idea.
我们非常应该
We should totally train
训练一支由优秀的深海钻孔工人组成的宇航员
a team of maverick deep sea oil drillers to be astronauts and…
不行 这太蠢了
No, that’s stupid.
所以我会认为火星上有生命吗?
So do I think there is life on Mars?
这至今也没有确凿的证据
Well, there’s no real evidence for it yet.
但这个星球在足够长的时间内确实存在着水和舒适的环境
But the planet was certainly wet and hospitable for long enough
并且不会像地球生命那样需要那么长时间起步
and didn’t take life that long to get started on earth.
这是可信的而且值得去探索
It’s very plausible and worth the hunt.
毕竟回报将是十分巨大的
After all the pay-off would be enormous.
在另一个星球上发现生命起源的契机
Finding even one incidence of life beginning on another planet
将会告诉我们宇宙中生命存在的可能性
would tell us words about the likelihood of life in the universe
如果你想了解我们在宇宙中的地位 这是非常重要的
kind of a big deal if you want to understand our place
毕竟目前看起来宇宙是一片死寂
in what’s so far seems an eerily empty
“太空”
Space Time.
朋友们 我会外出一段时间
Hey guys, I’ll be traveling for a little bit
所以在公共回复区会有一定程度的积压
so we can have a little bit of a backlog in common responses.
请你们放心 我们会一一查看的
I want to let you know that we will be getting to them all
下一期视频也会正常发布
and will be releasing episode on the normal schedule.
下周见
So see you next week.

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译制信息
视频概述

这是人类探寻火星生命的历史。路漫漫其修远兮,吾将上下而求索。

听录译者

收集自网络

翻译译者

钉子酷咸鱼

审核员

审核员XY

视频来源

https://www.youtube.com/watch?v=VmEY6T5Wc-Q

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