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

譯者: Lilian Chiu 審譯者: Helen Chang

On July 4, 2015,

2015 年 7 月 4 日，

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

美國太空總署太空船「新視界號」

在離地球五十億公里的地方。

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

它已經飛行了九年半， 離冥王星只有十天的距離，

when it suddenly dropped out of contact.

卻突然失去了聯絡。

But let’s back up a little.

但我們先倒帶一下。

As of 1989,

截至 1989 年，

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

人類已經成功將太空船送到 太陽系的所有已知行星，

except one—Pluto.

只差一個——冥王星。

You may have heard that astronomers don’t consider Pluto

你可能聽過天文學家

不將冥王星或它的兄弟視為行星。

or its brethren to be planets.

However, most planetary scientists still do,

然而，大部分的行星科學家 仍然將之視為行星，

which is why we're using that terminology here.

這就是為什麼在這裡 要用行星這個術語。

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

從地球，我們對 冥王星的了解很有限，

because it’s so far from us.

因為它離我們太遠了。

Pluto, however, is a scientific goldmine.

然而，冥王星可說是科學金礦。

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

它位在所謂的「古柏帶」，

home to many small planets,

這個區域是許多小行星、

hundreds of thousands of ancient icy objects,

數十萬個古老結冰物體，

and trillions of comets.

以及數兆個慧星的家。

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

這個神秘的區域內有著線索， 能協助了解我們的太陽系的形成，

and it was long, tantalizingly beyond our reach.

且它遠在我們所能及的距離之外。

Until New Horizons.

直到新視界號出現。

Its objectives: explore Pluto,

它的目標：探索冥王星、

collect as much scientific data as possible,

盡可能收集科學資料、

transmit it back to Earth,

將它傳回地球，

then explore farther out in the Kuiper Belt.

接著再進一步探索 古柏帶的更遠之處。

To achieve this, the New Horizons team outfitted their craft

為了達成這個目標，新視界號團隊 將他們的太空船裝配上

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

七種最先進的科學儀器。

Those included Ralph,

這些儀器包括「Ralph」，

a set of cameras powerful enough

它是一組攝影機，強大到

to capture features the size of city blocks in Manhattan

可以從數萬公里的距離捕捉到

from tens of thousands of kilometers away.

曼哈頓城市街區這麼大的特徵。

And REX, designed to use radio waves

還有「REX」， 它的設計是用無線電波

to measure Pluto’s atmospheric pressure and temperature.

來測量冥王星的大氣壓力和溫度。

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

所有太空船上的設備都必須要 打造得非常可靠且重量要很輕，

because New Horizons had an additional challenge;

因為新視界號有另一項額外的挑戰，

it had to reach its target as fast as possible.

它得要盡快到達目標。

Why?

為什麼？

Around 2020, Pluto will reach a point in its orbit

在 2020 年左右，冥王星就會 抵達其軌道上的一個點，

where its atmosphere could freeze.

在這個點，冥王星的 大氣可能會結冰。

And due to the tilt of its axis,

因為它的軸傾向角度，

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

每年冥王星上的表面會有 越來越多區域被黑暗掩蔽。

Pluto completes a full orbit once every 248 Earth years,

冥王星完整繞軌道一圈， 需要花 248 地球年，

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

所以要等到下一次 造訪的機會要等很久。

To see how New Horizons got to Pluto in time,

為了瞭解新視界號 如何及時到達冥王星，

let’s jump to its launch.

咱們先跳到它的發射。

Its three rocket stages accelerated New Horizons to such great speeds

新視界號有三節火箭， 能很快地加速，

速度快到抵達四十萬公里外的月球

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

只需九個小時。

About a year later, the craft reached Jupiter

大約一年後，太空船到了木星，

and got what’s called a gravity assist.

得到所謂的重力輔助。

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

也就是當它飛得夠靠近 這個氣態巨行星，

to receive a gravitational slingshot effect.

就能接收到一種重力彈弓效應。

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

新視界號接著能以 每小時五萬公里的速度飛行，

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

接下來的八年都是用這個速度， 飛過要抵達冥王星所剩下的路途。

Going at such an astonishing speed

用這麼驚人的速度飛行，

meant that slowing down to get into orbit or land

就意味著不可能減速下來

would’ve been impossible.

進入軌道或降落。

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

所以新視界號所執行的是 近天體探測飛行任務，

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

在這項任務中，它只有一次機會， 從冥王星旁呼嘯而過時進行觀察。

The flyby would have to be fully automated,

近天體探測飛行必須是全自動化的，

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

因為距離遠到任何 從地球發出的指引訊號

would take 4.5 hours to reach it.

都要四個半小時後才能收到。

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

所以，團隊在太空船的電腦上 裝載了一系列數千條指令，

called the core load,

稱為核心負載，

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

當太空船距離冥王星只有 六天半的時候就會開始執行。

But when New Horizons was just ten days out,

但當新視界號只差十天就到時，

disaster almost struck.

災難幾乎降臨。

Ground control lost contact with the spacecraft.

地面控制中心和太空船失去聯絡。

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

在焦慮了兩小時之後， 新視界號重新上線了，

but mission control discovered that its main computer had rebooted,

但任務控制中心發現 它的主要電腦已經重新開機過，

losing the entire core load and other critical data.

失去了所有核心負載 以及其他重要資料。

Without that, it would soon whizz by Pluto

沒有核心負載， 它很快就會疾速掠過冥王星，

with virtually nothing to show for the mission.

對於這項任務，真的就 沒有任何可展現的東西。

Alice Bowman, the mission’s Operations Manager,

這次任務的營運經理艾莉絲鮑曼

led a team for 72 sleepless hours to get the instructions

領導團隊花了 72 小時 不眠不休，

才將那些指令 及時重新載回新視界號。

loaded back into New Horizons in time.

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

在完全不容許一點差錯的情況下， 她和她的團隊圓滿達成任務，

and New Horizons began taking and broadcasting breathtaking images.

新視界號開始拍攝並播送 讓人屏息的影像。

Those observations have revealed a delightfully varied world,

那些觀察的資料揭示出 一個討喜的多變世界，

with ground fogs,

地面有霧，

high altitude hazes,

高空有霾，

possible clouds,

可能有雲、

canyons,

峽谷、

towering mountains,

高聳的山、

faults,

斷層、

craters,

火山口、

polar caps,

極冠、

glaciers,

冰河，

apparent dune fields,

顯然還有沙丘地，

suspected ice volcanoes,

可能有冰火山，

evidence for past flowing liquids,

這是過去有液體流過的證據，

and more.

還有更多。

One of the most exciting discoveries

最讓人興奮的發現之一

is the 1000-kilometer-wide Sputnik Planitia glacier.

就是一千公里寬的 史波尼克高原冰河。

Sputnik Planitia is mainly composed of slowly churning frozen nitrogen,

史波尼克高原主要的成份是 緩慢攪動的固態氮，

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

我們從未在我們的太陽系中 見過這樣的東西。

The exploration of Pluto was a great success,

冥王星的探索成功圓滿，

but New Horizons isn’t done yet.

但新視界號的工作還沒完。

On January 1, 2019,

2019 年 1 月 1 日，

it’ll break its own record for furthest explored object

它將打破史上探索最遠物體的記錄，

when it visits a Kuiper Belt Object called 2014 MU69,

這個記錄是它在造訪古柏帶物體 2014 MU69 時創下的，

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

那物體繞著太陽運行， 比冥王星更遠十億公里。

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

世界正摒息以待，等著看 它能在那裡發現什麼。