The journey to Pluto, the farthest world ever explored - Alan Stern

翻译人员: Yuntao Li 校对人员: Lipeng Chen

On July 4, 2015,

在 2005 年 7 月 4 日，

a NASA spacecraft called New Horizons was 5 billion kilometers away from Earth.

美国国家航空和宇宙航行局 (NASA) 的飞船

新视野号正在距离地球 50 亿公里的地方。

It was only 10 days away from Pluto, after flying for 9.5 years,

当它突然中断信号时候， 它已飞行了 9.5 年，

when it suddenly dropped out of contact.

离冥王星就只有 10 天的飞行时间。

But let’s back up a little.

但是让我们先了解一下它的背景。

As of 1989,

到 1989 年为止，

mankind had successfully sent craft to every known planet in the solar system

人类已经成功地将航天器送往 太阳系的所有已知行星，

except one—Pluto.

除了冥王星。

You may have heard that astronomers don’t consider Pluto

你也有听说过天文学家 不认为冥王星是行星，

or its brethren to be planets.

或者是它是行星的小弟弟。

However, most planetary scientists still do,

但是，绝大部分行星科学家 还是认为冥王星是行星。

which is why we're using that terminology here.

这就是我们使用这个术语的原因。

There’s a limited amount we can learn about Pluto from Earth

我们从地球上能了解 冥王星的知识很有限，

because it’s so far from us.

因为它离我们太远了。

Pluto, however, is a scientific goldmine.

然而，冥王星是科学的金矿。

It’s located in a region called the Kuiper Belt,

它处于名叫柯伊伯带的地区，

home to many small planets,

是众多小行星的家，

hundreds of thousands of ancient icy objects,

也是成百上千的古代冰体，

and trillions of comets.

以及数万亿彗星的家。

This mysterious region holds clues to the formation of our solar system,

这个神秘的地区拥有着 太阳系构成的线索，

and it was long, tantalizingly beyond our reach.

并且，它远远超出了 人类可以触及的范围，

Until New Horizons.

直到新视野号的出现。

Its objectives: explore Pluto,

新视野号的目的就是：探索冥王星，

collect as much scientific data as possible,

收集越多数据越好，

transmit it back to Earth,

并传送回地球，

then explore farther out in the Kuiper Belt.

然后探索柯伊伯带中更远的地方。

To achieve this, the New Horizons team outfitted their craft

为了达到这个目标， 新视野号研发团队让它全副武装，

with seven state-of-the-art scientific instruments.

装有七个超高水准的科学仪器。

Those included Ralph,

这包括拉夫，

a set of cameras powerful enough

一套足够强力的照相机，

to capture features the size of city blocks in Manhattan

能够从一万公里以外，

from tens of thousands of kilometers away.

捕捉曼哈顿的城市街区。

And REX, designed to use radio waves

以及REX，被设计使用无线电波，

to measure Pluto’s atmospheric pressure and temperature.

用于测量冥王星的大气气压和温度。

All of the onboard equipment had to be built to be both reliable and lightweight

所有的船上仪器必须 被制造的既可靠又轻,

because New Horizons had an additional challenge;

因为新视野号还有一个附加的挑战；

it had to reach its target as fast as possible.

它必须越快抵达它的目标越好。

Why?

为什么？

Around 2020, Pluto will reach a point in its orbit

大约在 2020 年，冥王星会抵达 其轨道上的一个点，

where its atmosphere could freeze.

在那个点它的大气层会凝结。

And due to the tilt of its axis,

而且因为它的轴的倾斜，

more and more of Pluto’s surface is shrouded in darkness every year.

冥王星越来越大的表面积 会被黑暗所笼罩。

Pluto completes a full orbit once every 248 Earth years,

冥王星的公转时间相当于 248 个地球年。

so it would be a long wait for the next prime opportunity to visit.

所以要等到下一个机会， 需要很长时间。

To see how New Horizons got to Pluto in time,

为了看到新视野号是 如何及时抵达冥王星，

let’s jump to its launch.

让我们一起跳到它发射的时候。

Its three rocket stages accelerated New Horizons to such great speeds

它的三个火箭阶段能够把新视野号 加速到足够的速度，

that it crossed the 400,000 kilometers to the moon in just nine hours.

以在九小时内抵达 400000 公里之外的月球。

About a year later, the craft reached Jupiter

在一年以后，飞船抵达木星

and got what’s called a gravity assist.

并得到我们说的重力协助。

That’s where it flies close enough to the gas giant

这就是它跟巨大气体行星 飞的足够近的地方，

to receive a gravitational slingshot effect.

为了受到引力弹弓效应。

New Horizons was then flying at around 50,000 kilometers per hour,

新视野号以每小时 50000 千米的速度飞行，

as it would for the next eight years to cross the remaining gulf to Pluto.

因此在未来的八年它会 穿过剩下的路程抵达冥王星。

Going at such an astonishing speed

达到一个这样惊人的速度，

meant that slowing down to get into orbit or land

就意味着减速进入轨道， 或者着陆，

would’ve been impossible.

是不可能的。

That’s why New Horizons was on a flyby mission,

这就是为什么新视野号执行的是 飞近探测任务，

where it would get just one chance to scream by Pluto and make its observations.

意味着他只有一次机会观察冥王星。

The flyby would have to be fully automated,

飞近探测任务是全自动的，

since at that distance, any signals to guide it from Earth

因为在如此遥远的距离， 任何从地球来的信号，

would take 4.5 hours to reach it.

都要耗费 4.5 小时才能抵达。

So the team loaded the ship’s computer with a series of thousands of commands,

所以研发团队在飞船的电脑里 载满了几千套命令，

called the core load,

叫做核心载入，

that would begin to execute when the craft was 6.5 days from Pluto.

这会在飞船距离冥王星 6.5 天 的时候开始执行。

But when New Horizons was just ten days out,

但是新视野号才刚刚发出十天，

disaster almost struck.

灾难几乎就毁灭了它。

Ground control lost contact with the spacecraft.

地面控制失去了与飞船的联系。

After two nerve-wracking hours, New Horizons came back online,

在令人紧张的两个小时之后， 新视野号终于重新连线，

but mission control discovered that its main computer had rebooted,

但是主控中心发现 主电脑已经重启，

losing the entire core load and other critical data.

所有的核心载入和 关键数据都已经失去。

Without that, it would soon whizz by Pluto

没有这些东西， 它很快就会直接掠过冥王星，

with virtually nothing to show for the mission.

但并不会完成任何任务。

Alice Bowman, the mission’s Operations Manager,

爱丽丝·伯曼，任务执行长，

led a team for 72 sleepless hours to get the instructions

带领团队持续工作 72 小时无休， 终于把指令

loaded back into New Horizons in time.

及时的加载回新视野号。

Without room for a single error, she and her team pulled it off,

没有一丝错误的空间， 她和她的团队圆满完成任务。

and New Horizons began taking and broadcasting breathtaking images.

而且新视野号开始拍摄并广播 令人激动的照片。

Those observations have revealed a delightfully varied world,

这些观测展现了一个 变化多端的世界。

with ground fogs,

有着地面雾气、

high altitude hazes,

高海拔烟雾、

possible clouds,

可能存在的云、

canyons,

大峡谷、

towering mountains,

高耸入云的山脉、

faults,

断层、

craters,

火山口、

polar caps,

极地冰冠、

glaciers,

冰川、

apparent dune fields,

明显的沙丘、

suspected ice volcanoes,

疑似的冰火山、

evidence for past flowing liquids,

过去流动液体的证据

and more.

和更多。

One of the most exciting discoveries

最令人激动的一个发现之一是

is the 1000-kilometer-wide Sputnik Planitia glacier.

1000 千米宽的史波尼克高原冰川。

Sputnik Planitia is mainly composed of slowly churning frozen nitrogen,

史波尼克高原主要由 缓慢搅动的固氮组成，

and we’ve never seen anything like it in our solar system.

我们从来没有在太阳系中 见过类似的事物。

The exploration of Pluto was a great success,

对于冥王星的探索是个大成功，

but New Horizons isn’t done yet.

但是新视野号的使命仍未完成。

On January 1, 2019,

在 2019 年 1 月 1 日，

it’ll break its own record for furthest explored object

它会打破自己创造的最远飞行记录，

when it visits a Kuiper Belt Object called 2014 MU69,

当它到达柯伊伯带上的 2014 MU69 (星体编号)，

which is orbiting the sun another billion kilometers farther away than Pluto.

这个星体相比冥王星距离太阳 又多出 10 亿千米。

The world is holding its breath to see what it’ll find there.

至于在那里会发现什么， 全世界都将为之屏息。