行星（2019）

保护火星的大气和大气之下的海洋
..keeping guard over the Martian atmosphere and seas below.
但在35亿到40亿年前
But between 3.5 and 4 billion years ago,
火星的发电机关闭了
Mars' dynamo switched off.
随着磁场的减弱 两极附近的极光
The aurora surrounding the poles slowly faded away
慢慢消失
as the magnetic field diminished...
于是火星大气开始被太阳风
..allowing the atmosphere to be stripped away
吹离
by the solar wind.
失去保护的海洋蒸发 地表结冰
Without protection, seas evaporated, the surface froze,
火星的地貌完全改变
and Mars was transformed.
地球 35亿年前
与此同时 火星的姐妹行星的命运
At the same time, the fortunes of Mars' sister world
即将发生截然不同的变化
were about to take a very different turn.
在接下来的10亿年里
For the next billion years or so, Earth was indistinguishable
地球和火星的早期地貌没有区别
from those landscapes of early Mars-
即一片被海洋包围的贫瘠大♥陆♥
barren continents surrounded by ocean.
但在地球的海洋中 生命开始改变地球
But in Earth's oceans, life was beginning to transform the planet.
原始海藻开始中和海洋的酸度
Primitive algae started to neutralise the ocean's acidity
并且用氧气替代红色浓雾
and replace the dense red fog of Earth's methane-rich
即富含甲烷的地球大气
atmosphere with oxygen.
约6亿年前 富含氧气的大气使复杂的生命
Around 600 million years ago, that oxygen-rich atmosphere allowed
得以在海洋进化 在陆地繁衍生息
complex life to evolve in the oceans, colonise the land,
并最终产生了如今这个充满生机的世界
and ultimately produce this almost-infinitely rich living world
而我们正是这个世界的一部分
today, of which we are a part.
火星死去 但地球欣欣向荣
While Mars died, Earth flourished.
为了解两颗姐妹行星为何命运如此不同的原因
To understand why the two sisters had such different destinies,
我们必须回到
you have to go right back
两颗行星的形成之初
to the time the planets were forming.
太阳系 45亿年前
在火星和地球诞生时
When Mars and Earth were born,
太阳系还是由气体和岩石组成的混沌旋涡
the solar system was a chaotic vortex of gas and rock.
物质聚集在一起 逐渐变大 然后又会被撞碎
Material clumped together and grew, only to be smashed apart.
随着时间的推移 有些物体变得足够大
Over time, some of the objects became large enough to survive
可以承受较小的撞击 并继续变大
at least the smaller impacts, and continued to grow,
这包括胚胎期的地球和火星
including the embryonic planets Earth and Mars.
但两颗行星有一个重要的不同
But there was one crucial difference between the young planets.
火星形成于太阳系中
Mars formed in a region of the solar system
岩石物质相对较少的区域
with considerably less rocky material.
这对行星的生长产生了深远的影响
And that had a profound impact on the planet's growth.
相对来说 火星要小很多 它的直径约为地球的一半
Mars is a significantly smaller world - it's about half the diameter
这也是两颗行星产生差异的原因
of the Earth, and that makes all the difference.
尽管我们并没有完全了解其中的细节
Although the details are not yet fully understood,
但可以明确的是 由于火星体积更小 导致它的发电机
it seems clear that Mars' smaller size meant that its dynamo switched
在数十亿年前关闭了
off many billions of years ago.
体积更小意味着火星的核心比地球的核心冷却得更快
Being smaller meant Mars' core cooled more quickly than Earth's.
这显然也是火星失去磁场的
And this is certainly part of the reason why Mars
原因之一
lost its magnetic field.
尽管火星与太阳的距离大于地球与太阳的距离
Even though the planet is further away from the sun than we are,
但太阳风带走了它的大气
that meant that the solar wind stripped away its atmosphere
火星死了
and Mars died.
因此 即使地球和火星在很多方面都很相似
So, even though Earth and Mars are so similar in so many ways,
二者在太阳系的位置和大小导致了
the difference in position and size in the solar system
它们完全不同的命运
led to very different fates.
很久以前 两颗姐妹行星诞生
Long ago, two sister worlds were born.
童年时期的火星温暖湿润
In childhood, Mars was warm and wet...
而地球荒凉且充满毒气
..whilst the Earth was inhospitable and toxic.
两颗年轻的行星都在晚期重大撞击事件中
Both young planets survived the violence
活了下来
of the Late Heavy Bombardment,
并成为成熟的行星
emerging as mature worlds,
具备了生命所需的所有要素
primed with all the ingredients for life.
但那颗小一些的行星的核心深处正在消亡
But deep inside, the smaller of the two was dying.
火星的海洋干涸
Mars' seas dried up.
随着火星内部的冷却 它的火焰也接连熄灭
And as the planet's interior cooled, one by one her fires went out.
奥林匹斯山是太阳系最大的火山
Olympus Mons, the largest volcano in the solar system,
它的最后一次喷发是在大约2500万年前
last erupted around 25 million years ago.
随着熔岩变成岩石
As the lava turned to stone,
火星被时间冻结
Mars was frozen in time.
因此 直至今日 它的表面依然满目疮痍 布满沙尘
And so, today, her surface lies rusted and gathering dust.
但这也许并不是火星故事的结局
But that might not be the end of Mars' story.
因为下一代太空探测器正在行动
Because the next generation of spacecraft are already on their way.
美国国家航♥空♥航♥天♥局猎户座飞船
美国国家航♥空♥航♥天♥局的猎户座飞船目前正在进行高级测试
NASA Orion - currently in advanced testing.
可搭载4名宇航员
比以往任何时候更深入太空
欧洲太空局“火星生命”
欧洲太空局的
ESA ExoMars -
“火星生命”探测联合任务旨在寻找火星的生命迹象
a fleet of spacecraft designed to search for signs of life.
这是有史以来最具野心的私人太空计划
And the most ambitious private space mission ever conceived.
美国太空探索技术公♥司♥ 重型猎鹰火箭
世界上最强大的火箭
科学家研发出可将人类送往火星表面的运载火箭
A launch vehicle developed to take humans to the surface of Mars.
火星在某种意义上是一个失败的世界
Mars is, in a sense, a failed world,
它是一抹褪色的余烬 上面镌刻着代表火星迷人过去的记忆
a faded ember etched with the memories of a more enticing past,
但火星上曾经有过 也许仍有生命存在
but there may have been, and may still be, life on Mars.
同时 在太阳系发现第二种生命形式
And the discovery of a second genesis in our solar system
将产生深远的哲学 科学和文化影响
would have profound philosophical, scientific and cultural consequences
因为这意味着生命起源
because it would mean there is a sense of inevitability
存在必然性
about the origin of life,
这意味着宇宙中
and that would mean that the universe
可能会充满生命 我们并不孤单
is most likely teeming with life - that we are not alone.
但我认为同样重要的是 像火星这样历史久远的行星
But equally importantly, I think, is the role that a planet
在未来可能发挥的作用
with a history like Mars could play in our future.
火星上资源丰富 它的地下蕴藏着
Mars is rich in resources, it has vast reservoirs of frozen
丰富的冰冻水 还有矿物质
water below the surface, and minerals -
像铁 氮 碳 氧 这些都是
iron, nitrogen, carbon, oxygen - all the things
文明发展所需的要素
you need to support a civilisation.
因此我认为 在我有生之年
And that's why I think that, in my lifetime,
将出现火星人 火星人就是我们
there will be Martians, but the Martians will be us.
我们将前住火星定居
We will go to Mars and make it our home,
这颗古老的红色星球将成为我们人类走出地球
and that old red world will become our first step
实现星际漫游的第一步
beyond the cradle, and out to the stars.
《行星》幕后故事
火星确实激发了
Mars really captures
詹妮弗·艾根博德博士 美国国家航♥空♥航♥天♥局戈达德太空飞行中心
我们的想象力
our imagination,
部分原因是它离地球很近
partly because it's so close.
我认为人类对火星非常感兴趣 是因为
I think people are really interested in Mars because it actually
约翰·格勒青格教授 加州理工学院
它与地球很相似
is so similar to Earth.
火星离地球很近 我们可以带着机器人和飞行任务
It's close by, it's easy to travel there with robots
前往火星 事实上我们已经进行过很多探索
and space missions, and so we've done a lot of exploration.
每次前往火星都会有新的发现
And, every time you go and look, you discover something new.
美国国家航♥空♥航♥天♥局于2011年11月26日发射“好奇”号♥火星探测器
NASA Curiosity launched on the 26th of November, 2011.
但科学家面临的最大难题
But the biggest obstacle facing the mission team
不是如何离开地球
wasn't leaving the Earth.
与我们通过太空探测器前往的其它地方相比
Mars has a unique set of challenges
火星给我们带来一系列独特的挑战
compared to other places we go with spacecraft.
阿什温·瓦萨瓦达博士 美国国家航♥空♥航♥天♥局喷气推进实验室
火星有大气层 但它很稀薄 不足以
Mars has an atmosphere but it's thin, so it's not enough
让我们的速度慢下来
to really slow you down,
但在我们试图着陆时又足以让我们燃烧起来
but it is enough to actually burn you up as you're trying to land.
“好奇”号♥以每小时两万公里的速度
Curiosity reached the top of the Martian atmosphere,
抵达火星大气层的边缘
travelling at 20,000km per hour.
“好奇”号♥是一个巨大的探测器 它重达一吨♥
Curiosity is a big rover. It weighs a metric ton,
因此要让它成功着陆
and so landing that required every trick in the book
我们必须从以往的任务中学习着陆火星的所有技巧
of how we've learned to land on Mars with previous missions.
为了安全着陆 “好奇”号♥必须将速度减到
To land safely, the rover had to be slowed
每小时4000公里以下
to less than 4km per hour.
航♥天♥器到达火星时的速度很快
You end up arriving at Mars going really fast,
因此必须减速
so you actually have to slow down,
我们通过一个防热罩实现减速的目的
and we do that using a heat shield,
航♥天♥器会燃烧很多燃料 产生大量热量
which burns off a lot of energy and creates a lot of heat,
因此我们必须吸收这些热量 防止损坏航♥天♥器
so you have to absorb that somehow and not damage the spacecraft.
接下来 降落伞登场
Then a parachute comes out.
这是我们在行星探测任务中使用的最大的降落伞
The biggest parachute we've ever used in a planetary mission.
它甚至无法使“好奇”号♥降到需要的速度
And that even doesn't slow Curiosity down enough,
因为火星的大气层太稀薄了 因此火箭将携带探测器
because Mars' atmosphere is quite thin, so then rockets carry