了解宇宙是如何运行的（2010）

How the Universe Works S08E02

Part 6 Jan. 30, 2022, 2:58 p.m.

为了摆脱地球引力
Narrator: To break free
from earth's gravity,
火箭必须以每小时25000英里（约40000多公里）的速度飞行
the space rocket must travel
at 25,000 miles an hour.
为了实现这一目标
To achieve that,
NASA 正在建造世界上最强大的火箭
nasa is building the most
powerful rocket in the world.
太空发射系统，简称 s.L.S，是一种火箭
The space launch system,
or s.L.S., is the rocket
它被设计用来将猎户座带离地球
that's being designed
to carry orion off of earth
并超越近地轨道
and beyond low earth orbit.
萨特:我们的理念是，“嘿，还记得”
Sutter:
And the philosophy is, "hey,
remember those big rockets
“我们在60年代制♥造♥的那些大火箭吗?”
that we used to make back
in the '60s and stuff?
“让我们再来一次，但要更大”
Let's do that again
but more so."
拉德堡:真的很大
radebaugh: It's really big.
它比为运载阿波罗飞船
It's larger than
the saturn v rocket
而建造的土星五号♥火箭还要大
that was built to carry
the apollo spacecraft
因此它将是建造的最大的火箭
and is therefore going to be
the largest rocket built.
太空发射系统
Narrator:
The space launch system
will be taller
将比自♥由♥女神像还要高
than the statue of liberty.
其巨大的发动机
Its gargantuan engines
will thrust the rocket
将以16万艘轻巡洋舰的马力
through the atmosphere
推动火箭穿越大气层
with the horsepower
of 160,000 corvettes,
产生880万磅的推力
producing 8.8 million pounds
of thrust.
s.L.S. 将能够将猎户座太空舱发射到太空
The s.L.S. Will be able to blast
the orion capsule into space
并将其送往火星
and send it on its way to mars.
不幸的是，火箭落后于预定计划
Unfortunately, the rocket
has fallen behind schedule.
它的首次试飞定于2017年12月
Its maiden test flight was set
for December of 2017.
现在计划在2020年底举♥行♥
<太空发射系统已于肯尼迪航♥天♥中心的飞行器装配大楼内>
<成功完成了火箭核心级的工程测试系列，目前还是按照>
<2024年登月为实施目标推进，但是难度很大——译者注>
Now it's scheduled
for the end of 2020.
批评者看到了 s.L.S. 认为这是浪费钱
Critics see the s.L.S.
As a waste of money,
据报道该项目超出预算数十亿美元
with the project reported to be
billions of dollars over budget.
人们仍然希望 NASA 的太空发射系统
It's still hoped
nasa's space-launch system
能在本世纪30年代到达火星
will go to mars
in the 2030s.
但是，即使这颗红色的行星是我们的邻居
But even though the red planet
is our neighbor,
我们访问的时间安排将很复杂
the timing of our visit
will be complicated.
普莱特:如果你计划家庭度假
Plait: If you're planning
a family vacation
你只要准备好车子，这很简单，对吧？
and you want to get in the car,
it's easy, right?
你看着地图说我住在“a”市
You look at a map
and you say I live in city "a"
我要去“b”市
and I want to go to city "b"
我就走高速公路去吧
and I'll just take
the highways there."
好的，完美
well, great.
现在想象一下“a”市正在以每小时50英里（约80公里）的速度
Now imagine that city "a"
is moving this way
向这边移♥动♥
at 50 miles per hour,
而那座城市正以每小时200英里（约3220公里）的速度向另一边移♥动♥
and this city is moving this way
at 200 miles per hour.
现在你该怎么办？
Now what do you do?
嗯，与到达另一个星球相比
Well, that is a very
small problem
这是个很小的问题
compared to getting
to another planet.
火星任务的时间表
The timeline
of a mars mission,
日程安排，不介意我这么说的话
the scheduling,
if you will,
都是由天体力学
is all governed
by celestial mechanics,
行星的轨道来决定的
the orbits of the planets.
这并不是说只要你想去火星
It's not just
you pick a time to go to mars
你就可以随便挑个时间去
randomly
whenever you feel like going.
你需要等待
You've literally got to wait
行星排成一线，对吧？
for the planets
to be aligned, right?
泰勒:地球到火星的平均距离
Thaller:
On average, the distance
from the earth to mars
是1.4亿英里（约2.25亿公里）
is about 140 million miles.
但这一直在变化
But this is changing
all the time
因为我们都是围绕太阳运行的行星
because we are both plants
that are orbiting the sun.
地球离火星最近的距离
So about the closest
that earth ever comes to mars
大约是3500万英里（约5600万公里）
is a distance of about
35 million miles.
杜尔达:但某些时候，当我们在
Durda: But on other times
when we're on the opposite side
太阳与火星的另一边时
of the sun from mars,
火星的距离可能高达2.5亿英里（约4亿公里）
it can be as much
as 250 million miles.
在火星最接近的时候发射
Narrator:
Launching near the time
就缩短了旅程
of mars' closest approach
shortens the journey
这样 NASA 可以节省燃料和资源
so nasa can save on fuel
and resources,
提高任务成功的机会
boosting the mission's
chances of success,
但这种行星排列只是每26个月发生一次
but this planetary alignment
only happens every 26 months.
因此，如果 NASA 错过了发射窗口期
So if nasa misses
a launch window,
它将不得不再等待两年多的时间再进行一次发射
it'll have to wait over
two years for another go.
但仅仅选择正确的时间是不够的
But simply picking
the right time isn't enough.
火星和地球都绕着太阳转
Mars and the earth
are both orbiting the sun.
所以猎户座飞船不能直线飞向火星
So orion can't fly
in a straight line to mars.
相反，它将使用所谓的霍曼转移
Instead, it'll use what's known
as a hohmann transfer.
我们想做的是把我们自己放在
What we want to do is sort of
put ourselves on our spacecraft
绕太阳轨道的航♥天♥器上
in orbit around the sun
这样我们就可以从地球上开始
so we might start right here
on earth,
发射我们的航♥天♥器
launch our spacecraft,
这样，基本上，我们只是做一个漂亮的，柔和的弧线
and, essentially,
we just make a nice, gentle arc
围绕着太阳旋转
that's arcing around the sun
然后它就可以自然地滑入这个轨道
so that it can naturally slide
into this orbit
最后到达火星
and then end up on mars.
整个旅程大约需要10个月
Narrator: The journey will take
around 10 months.
要想更快到达那里就意味着要消耗更多的燃料
To get there quicker means
burning more fuel,
这不是一个选择
which is not an option.
在被火星引力捕获之前
The hohmann transfer
keeps fuel usage low
霍曼转移将航♥天♥器
by putting the craft
in an orbit
置于一个逐渐与火星轨道相交的轨道上
that gradually intersects
with the orbit of mars
从而保持低燃料使用量
before being captured
by the red planet's gravity.
但船员们需要把握好方向
But the crew will need to get
their direction just right.
杜尔达:根据轨道运行的方式
Durda:
The way the orbits work,
你要瞄准的方向
you've got to aim a little
bit different direction
和火星现在的位置有点不同
from where mars appears
to be now.
你必须瞄准当你到达那里时它会在哪里的位置
You got to aim for where it's
going to be when you get there.