On July 4, 2015, a NASA spacecraft called New Horizons was 5 billion kilometers away from Earth.

2015 年 7 月 4 日，NASA 稱為「新視界號」的太空船距離地球 50 億公里遠。

It was only 10 days away from Pluto after flying for 9.5 years when it suddenly dropped out of contact.

飛行 9 年半、再 10天 就能抵達離冥王星的它突然失聯了。

But let's back up a little.

讓我們先把時間往回推一點。

As of 1989, mankind had successfully sent craft to every known planet in the solar system except one⏤Pluto.

截至 1989 年，人類已經成功將太空船送上所有已知的太陽系行星，除了冥王星之外。

You may have heard that astronomers don't consider Pluto or its brethren to be planets.

你可能聽過有些天文學家不將冥王星或它的兄弟視為行星。

However, most planetary scientists still do, which is why we're using that terminology here.

然而，大部分行星科學家還是把它算在內，這就是為什麼我們這裡還是使用行星這個詞。

There's a limited amount we can learn about Pluto from Earth because it's so far from us.

我們從地球上對冥王星的了解很有限，因為它離我們太遠了。

Pluto, however, is a scientific goldmine.

然而，冥王星可是個科學金礦。

It's located in a region called the Kuiper Belt, home to many small planets, hundreds of thousands of ancient icy objects, and trillions of comets.

它位於一個被稱做「古柏帶」的區域，在那裡有許多的小行星、成千上萬的古老冰體，還有上兆個慧星。

This mysterious region holds clues to the formation of our Solar System, and it was long, tantalizingly beyond our reach.

這個神祕的區域內我們太陽系形成的線索，而且它遠在我們所能到達的區域之外。

Until New Horizons.

直到新視界號的出現。

Its objectives?

它的目的呢？

Explore Pluto, collect as much scientific data as possible, transmit it back to Earth, then explore farther out in the Kuiper Belt.

探索冥王星、盡可能收集科學數據、把資料傳回地球，然後探索古柏帶更遠處。

To achieve this, the New Horizons team outfitted their craft with 7 state-of-the-art scientific instruments.

為了達到這個目標，新視界號團隊在他們的太空船上配備了 7 種最先進的科學儀器。

Those included Ralph, a set of cameras powerful enough to capture features the size of city blocks in Manhattan from tens of thousands of kilometers away.

包括 Ralph 這組攝影機，功能強大到可以從數萬公里外的距離捕捉到曼哈頓城市街區大小的特徵。

And Rex, designed to use radio waves to measure Pluto's atmospheric pressure and temperature.

還有設計目的是透過無線電波來觀測冥王星大氣壓力和溫度的 Rex。

All of the onboard equipment had to be built to be both reliable and lightweight because New Horizons had an additional challenge.

所有在太空船上的設備都要打造得又輕又可靠，因為新視界號還有個額外的挑戰。

It had to reach its target as fast as possible.

它必須盡最快的速度完成目標。

Why?

為什麼呢？

Around 2020, Pluto will reach a point in its orbit where its atmosphere could freeze.

大約西元 2020 年，冥王星就會運行到它軌道上的某一點，在那裡大氣可能會結凍。

And due to the tilt of its axis, more and more of Pluto's surface is shrouded in darkness every year.

還有因為冥王星的軸心傾斜角度，每年它的表面會有越來越多區域被黑暗籠罩。

Pluto completes a full orbit once every 248 Earth years, so it would be a long wait for the next prime opportunity to visit.

冥王星每經過 248 地球年才會繞完軌道一圈，所以在下個最佳時機到來將是場漫長的等待。

To see how New Horizons got to Pluto in time, let's jump to its launch.

要了解新視界號怎麼及時抵達冥王星，我們就跳到它的發射吧。

Its three rocket stages accelerated New Horizons to such great speeds that it crossed the 400,000 kilometers to the moon in just 9 hours.

新視界號的三節火箭能讓它很快地提升到一定的速度，這速度快到讓它只需要 9 小時就能穿過 40 萬公里抵達月球。

About a year later, the craft reached Jupiter and got what's called a "gravity assist".

大約一年後，太空船就會抵達木星，然後得到所謂的重力助推。

That's where it flies close enough to the gas giant to receive a gravitational slingshot effect.

也就是當它夠靠近這個巨大的氣態行星時，會接收到一種重力彈弓效應。

New Horizons was then flying at around 50,000 kilometers per hour, as it would for the next 8 years to cross the remaining gulf to Pluto.

然後新視界號就能以大約每小時 5 萬公里的速度飛行，接下來的 8 年都保持這個速度飛過抵達冥王星前的黑暗路途。

Going at such an astonishing speed meant that slowing down to get into orbit or land would've been impossible.

以這麼驚人的速度飛行代表它不可能減速下來進入軌道或降落。

That's why New Horizons was on a flyby mission, where it would get just one chance to screen by Pluto and make its observations.

這就是為什麼新視界號的任務是飛行任務，而它只有一次機會從冥王星旁呼嘯而過並進行它的觀測任務。

The flyby would have to be fully automated since, at that distance, any signals to guide it from Earth would take 4.5 hours to reach it.

這次飛行必須是全自動化的，因為在這麼遠的距離，任何從地球發送的指引訊號都要花費 4 小時半才會到達。

So, the team loaded the ship's computer with a series of thousands of commands called the "core load" that would begin to execute when the craft was 6.5 days from Pluto.

所以團隊在太空船的電腦裡裝載一系列上千條的指令，稱之為「核心負載」，當太空船距離冥王星只有 6 天半的距離時，就會開始執行。

But when New Horizons was just 10 days out, disaster almost struck.

但當新視界號距離冥王星只剩 10 天距離時，悲劇幾乎降臨。

Ground control lost contact with the spacecraft.

地球的控制中心跟太空船失聯。

After 2 nerve-wracking hours, New Horizons came back online.

在極度不安的 2 小時候，新視界號又上線了。

But mission control discovered that its main computer had rebooted, losing the entire core load and other critical data.

但任務控制中心發現它的主要電腦系統已經重啟，失去了所有核心負載跟其它關鍵資料。

Without that, it would soon whizz by Pluto with virtually nothing to show for the mission.

沒有那些，它馬上就會從冥王星旁急速掠過，然後這個任務中就沒有任何實質的東西可以展現。

Alice Bowman, the mission's Operations Manager, led a team for 72 sleepless hours to get the instructions loaded back into New Horizons in time.

這項任務的營運經理 Alice Bowman 領導一個團隊花了 72 小時不眠不休來讓那些指令及時裝載回新視界號。

Without room for a single error, she and her team pulled it off, and New Horizons began taking and broadcasting breathtaking images.

在不容許一絲差錯的情況下，她跟她的團隊完美達成任務，新視界號也得已開始拍攝並且傳送令人屏息以待許久的影像。

Those observations have revealed a delightfully varied world,

這些觀測揭露出一個討喜而多變的世界，

with ground fogs, high altitude hazes, possible clouds,

地上有薄霧、高空陰霾、可能有雲、

canyons, towering mountains, faults, craters,

有峽谷、高聳山峰、地表斷層、隕石坑、

polar caps, glaciers, apparent dune fields, suspected ice volcanoes, evidence for past flowing liquids, and more.

極冠、冰河、明顯的沙丘地、可能的冰火山、曾有流動液體的證據，等等。

One of the most exciting discoveries is the 1,000-kilometer-wide Sputnik Planitia glacier.

最讓人興奮的發現之一就是 1,000 公里寬的史波尼克冰凍高原。

Sputnik Planitia is mainly composed of slowly churning frozen nitrogen, and we've never seen anything like it in our solar system.

史波尼克冰凍高原主要的成份是攪得緩慢的固態氮，而在我們的太陽系中從未見過類似的物體。

The exploration of Pluto was a great success, but New Horizons isn't done yet.

這次的冥王星探索是個大成功，但新視界號還沒結束任務。

On January 1, 2019, it'll break its own record for furthest-explored object when it visits a Kuiper Belt Object called 2014 MU69,

在 2019 年 1 月 1 日，當它成功拜訪古柏帶名為 2014 MU69 的物體時，將打破史上最遠探索物體的記錄，

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

這個物體繞行太陽的軌道的長度比冥王星的還要遠上 10 億公里。

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

世界正屏息以待，想看看它能在那裡發現什麼。

The author of this lesson, Dr. Alan Stern, is a planetary scientist and the leader of the New Horizons mission.

本課的作者 Alan Stern 博士是一位行星科學家，同時是新視界號的領導人。

He worked for over 26 years, leading a team of hundreds to accomplish this incredible act of exploration.

他已經工作了 26 年，帶領數百人的團隊完成這次了不起的探險。

For the full story, we highly recommend Alan's book, "Chasing New Horizons: the Epic First Mission to Pluto", co-authored with planetary scientist David Grinspoon.

若想知道完整的故事，我們推薦 Alan 與行星科學家 David Grinspoon 合著的《冥王星任務：NASA 新視界號與太陽系盡頭之旅》一書。