1000公里長的星際纜繩——天鉤：英語精讀講義

Getting to space is hard.

進入太空並非易事。

Right now,

就目前而言，

it's like going up a mountain on a unicycle with a backpack full of explosives. 表達脈絡

就像騎著單輪車，背著滿滿一包炸藥上山。

Incredibly slow,

速度慢得驚人，

you can't transport a lot of stuff,

帶不了多少東西，

and you might die.

而且隨時可能喪命。

A rocket needs to reach a velocity of about 40,000 km/h to escape from Earth. 片語搭配

火箭要逃離地球，速度得達到大約每小時四萬公里。

To get to that speed,

為了達到這個速度，

rockets are mostly containers for fuel with a tiny tip of payload.

火箭內部幾乎全用來裝燃料，只有頂端一小塊地方留給有效酬載。

This is bad if you want to go to other planets

這對前往其他星球來說可不是個好消息，

because you need a lot of heavy stuff

因為你需要帶上大量重型設備，

if you want to survive and maybe even come back.

才能在上面生存，甚至有朝一日還能重返地球。

So,

那麼，

is there a way to get to space

有沒有一種方法可以進入太空，

with less fuel and more payload?

既能省燃料，又能多帶些有效酬載呢？

A nice thing that solved most of our transport problems on Earth

在地球上，有個好東西解決了我們大部分的運輸難題，

is what you call infrastructure.

那就是基礎設施。

Whether it's roads for cars, 文法

無論是汽車跑的公路、

ports for ships,

船舶停靠的港口，

or rails for trains,

還是火車行駛的鐵軌，

we've made it easier to get to places. 文法

都讓出行變得更輕鬆。

We can apply the same solution to space travel.

我們可以把這個方案應用到太空旅行上。

Space infrastructure will make getting into orbit

太空基礎設施將讓進入軌道，

and out to the Moon,

甚至前往月球、

Mars,

火星，

and beyond easier and cheaper.

乃至更遠的地方變得更輕鬆、更便宜。

Great.

太棒了。

But what exactly is space infrastructure?

但太空基礎設施到底是什麼呢？

Unlike an Earth space elevator, 表達脈絡

與地球上的太空電梯不同，

which is currently science fiction,

那目前還只是科幻小說，

there is a simple yet promising technology

現在有一項簡單卻極具前景的技術

that does not require new science,

不需要全新的科學、

magic materials,

神奇的材料，

or huge investments,

或是巨額的投資，

and that has been tested successfully in orbit already. 文法

而且已經在軌道上成功測試過。

A cable and a weight,

只需要一根纜繩和一個配重，

known as a tether. 片語搭配

被稱為「系繩」（tether）。

The concept is so simple, 文法

這個概念簡單到

it's surprising.

讓人驚訝。

What if we put tethers, 語氣意圖

如果我們把系繩，

hundreds or thousands of kilometers long,

幾百或幾千公里長，

into space

放到太空中，

and had spacecraft use them as ladders to climb to higher altitudes and gain speed? 文法

讓太空船把它當成梯子，爬到更高的地方並加速呢？

This concept is known as the skyhook.

這種概念被稱為「天鉤」（skyhook）。

It works even better if we make it spin.

如果讓它旋轉起來，效果甚至會更好。

A counterweight holds a long cable in place

用一個配重固定住長長的纜繩，

while it rotates around a circle.

讓它繞著圓心旋轉。

A rotating tether slows down its tip

旋轉的系繩會減慢其底端的速度，

relative to the ground at the bottom 片語搭配

相對底部的地面而言，

and speeds it up at the top like a catapult.

並在頂端像投石機一樣為其加速。

This means that you can transfer energy from the tether

這意味著你可以從系繩中獲取能量，

and get a massive boost when released,

在鬆開時獲得巨大的推力，

more or less for free, 片語搭配

而且這幾乎是免費的，

equal to twice the tether's rotation velocity.

相當於系繩旋轉速度的兩倍。

Specialized fibers already exist

特殊纖維已經面世，

that can survive the extraordinary stresses a skyhook would be faced with. 片語搭配

它們可以承受天鉤面臨的極大拉力。

To protect against cuts and collisions from debris and meteorites,

為了防止被太空碎片和隕石割斷或撞毀，

we can thread our tether into a web of redundant fibers.

我們可以將系繩編織成網狀的冗餘纖維結構。

Since our skyhook would pass over the same spot many times a day,

由於天鉤每天都會多次經過同一個地點，

this would allow small reusable shuttles to catch up with it. 片語動詞

那些可重複使用的小型太空梭就能順利追上它。

Of course, 表達脈絡

當然，

it's not that easy.

事情沒那麼簡單。

At its lowest point,

在最低點時，

the tether's tip is dashing through the atmosphere at around 12,000 km/h.

系繩末端正以大約一萬兩千公里的時速穿越大氣層。

Because of Earth's atmosphere,

因為地球有大氣層，

we can't lower the skyhook too much or it will get too hot from air friction.

我們不能把天鉤放得太低，否則會因空氣摩擦而過熱。

So,

所以，

it will dip to a height of 80 to 150 km and no lower.

它的最低高度將被限制在80到150公里之間，不能再低了。

To match this,

為了配合它，

we'll need specialized spacecraft that can get to the tether.

我們需要能飛抵系繩處的特殊太空船。

While this isn't exactly easy, 文法

雖然這也不容易，

it's still much cheaper than getting a big tin can filled with rocket fuel to go 40,000 km/h. 慣用語

但總比給一個裝滿火箭燃料的大鐵罐加速到每小時四萬公里要便宜得多。

Catching the tip will be a challenge, too.

抓住末端也是一項挑戰。

There's only a short time window of 60 to 90 seconds 片語搭配

只有60到90秒的短暫窗口期，

to find a tiny thing in the sky moving at Mach 12.

讓你在天空中尋找一個以12馬赫飛行的微小物體。

To make this easier,

為了降低難度，

the tip could have a sort of fishing line,

可以在末端繫上類似釣魚線的東西，

a kilometer long,

長度一公里，

with a navigation drone that helps the spacecraft connect.

搭配導航無人機，幫助太空船完成對接。

Another challenge is keeping our skyhook in orbit. 表達脈絡

另一個挑戰是讓天鉤保持在軌道上。

As more and more ships latch onto it and pull themselves up, 片語動詞

隨著越來越多的太空船勾住它並向上爬，

they use up the momentum that keeps it in place. 片語動詞

它們會消耗掉讓天鉤維持位置的動量。

If we don't do anything,

如果我們什麼都不做，

it will slow down and crash into the atmosphere.

它的速度就會變慢並墜入大氣層。

And here,

在這裡，

we can cheat the universe a bit. 慣用語

我們可以稍微「作弊」一下。

The skyhook is a battery of orbital energy. 慣用語

天鉤就是軌道能量的「電池」。

It's possible to balance the payloads coming in and being sent off. 文法

我們有可能平衡往返的有效酬載。

Arriving ships bringing humans and materials home to Earth add energy to the tether,

那些將人類和物資帶回地球的抵達太空船會為系繩增加能量，

which it can give to other ships departing into space.

它便能將這些能量傳遞給其他出發前往太空的太空船。

This way,

這樣一來，

the tether doesn't lose any energy.

系繩就不會損失任何能量。

The more we use it, 文法

我們用得越多，

the cheaper it gets.

成本就越低。

If we're still losing energy with each boost,

如果在每次加速時仍然在損失能量，

we can recover it with small electric or chemical engines that regularly correct the tether's position.

我們可以用小型電動或化學發動機來恢復它，定期修正系繩的位置。

A set of tethers,

如果有一套系繩系統，

one around Earth and one around Mars,

一個繞地球，一個繞火星，

could make trips between the planets fast, straightforward,

就能讓往返兩顆行星之間的旅行變得快速、直接，

and low-cost compared to rockets.

並且比火箭便宜得多。

The Earth tether would sit in low Earth orbit 文化背景

地球的系繩將位於近地軌道，

to grab people and payloads and fling them off to Mars.

抓取人員和貨物，將他們甩向火星。

The Mars tether catches them and slows them down for a landing on the surface.

火星的系繩則負責接住他們並減速，以便在表面著陸。

In the opposite direction,

反過來，

the tether could pick up a vehicle traveling through Mars's thin atmosphere at only about 1,000 km/h, 片語動詞

系繩也可以抓取在火星稀薄大氣中僅以約1000公里時速飛行的載具（

not much faster than our airliners on Earth,

沒比地球上的客機快多少），

and fling it back to Earth to be caught and lowered down.

再將它甩回地球，被抓取並降落。

The tethers could shorten trips between both planets from 9 months 片語搭配

這些系繩能將兩顆行星之間的旅程從9個月縮短

down to 5 or even 3

到5個月甚至3個月，

and reduce the scale of the rockets required by between 84 and 96%.

並且把所需火箭的規模減少84%到96%。

Even better,

更好的是，

people may be able to travel in relative luxury

人們或許能在相對奢華的環境中旅行，

as we could afford to invest in passenger comfort.

因為我們有餘裕在乘客的舒適度上進行投資了。

Tether travel would be first class seats to Mars. 慣用語

系繩旅行將是前往火星的頭等艙。

Together,

綜上所述，

tethers around Earth and Mars

地球和火星周圍的系繩

could provide the rapid and cost-efficient transportation backbone 慣用語

可以提供快速且具成本效益的運輸骨幹網路，

that would make space travel affordable.

讓太空旅行變得負擔得起。

But let's go further. 表達脈絡

但讓我們想得更遠些。

Starting from low Mars orbit,

從火星低軌道出發，

a tether could boost ships to the asteroid belt.

系繩還可以將太空船推向小行星帶。

The first craft sent to a new asteroid would need rockets to slow down at its destination. 表達脈絡

第一艘前往新小行星的太空船需要在目的地使用火箭減速。

Subsequent arrivals might find a tether waiting to catch them

而後來抵達的太空船或許會發現一根系繩已經在那裡等著接住他們，

and send them back for free.

並免費將他們送回。

Getting to asteroids cheaply

以低廉的成本前往小行星

is a major factor in opening up the resources of the solar system. 片語動詞

是開發太陽系資源的關鍵因素。

Precious metals and valuable minerals could be delivered to Mars

貴金屬和有價值的礦物可以被運往火星，

just weeks after they were cut out of their asteroid.

就在它們從小行星上開採出來幾週之後。

They would be the perfect building blocks for our interplanetary civilization. 慣用語

它們將是我們建立星際文明的完美基石。

But why stop here? 表達脈絡

可是為什麼要止步於此呢？

Mars's moons are very convenient.

火星的衛星非常方便。

No other moons in the solar system orbit that close to their planet.

太陽系中沒有其他衛星離它們的行星這麼近。

Phobos is so heavy that we don't need to worry about slowing it down, 文法

火衛一非常重，我們完全不用擔心它會減速，

making it the perfect attachment point 文法

這讓它成為絕佳的附著點，

for super tethers just under 6,000 km long.

可以用來連接不到6000公里長的超級系繩。

The lower tip would fly just over the surface of Mars and be very easy to catch.

較低的末端將直接在火星表面上空飛行，非常容易抓取。

The upper tip can fling ships all the way to Jupiter and Saturn.

而較高的末端則能將太空船一路甩向木星和土星。

The same super tether can also bring the inner solar system closer.

同樣，這根超級系繩也能拉近內太陽系的距離。

Venus and Mercury are a single swing away. 慣用語

只需一次甩動就能到達金星和水星。

Unlike Mars,

與火星不同，

they're bursting with solar energy 片語搭配

它們蘊藏著豐富的太陽能，

and are rich in minerals.

且礦物資源豐富。

In the long term,

從長遠來看，

nothing is stopping humanity from constructing a zero propellant transport network 文法

沒有什麼能阻止人類構建一個零推進劑的交通網絡，

for the terrestrial planets

覆蓋類地行星，

centered on the Martian moons.

並且以火星的衛星為中心。

Tethers are a comparably cheap and sustainable solution to making space travel affordable 文法

系繩是一種相對便宜且可持續的解決方案，讓太空旅行更加親民，

and the rest of the solar system accessible

並讓太陽系的其他地方觸手可及，

for exploitation and exploration.

方便我們進行探索與開發。

Considering that we have the technology to build them today, 表達脈絡

考慮到我們今天已經擁有了建造它們的技術，

there's really no good excuse to wait any longer. 語氣意圖

真的沒有好理由再等下去了。

Parts of the solar system are far away, 表達脈絡

太陽系的某些部分確實遙遠，

but they could be very close.

但它們原本可以離我們非常近。