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星际高速路

Take a Ride on the Interplanetary Superhighway

Brilliant机构支持的节目SciShow
SciShow Space is supported by Brilliant.org.
[前导音乐]
[ ♪ Intro ]
不管你的任务是什么
No matter what your mission is,
进入宇宙空间的最大障碍是燃料 很显然
one of the biggest obstacles to getting to space is fuel. Obviously,
你需要一些燃料来离开地面
you need some to get off the ground.
但是燃料也很沉重
But fuel is also heavy,
所以如果你想将一整个火箭送上天
so if you want to lift a full rocket,
你将会需要更多的燃料
you’re going to need more of it.
但是那将使所有的东西更加重 因此你将需要更多的燃料
But that just makes everything heavier, so then you need even more fuel.
如此循环
And on and on.
这是一个阻止我们在一趟旅行中
This is a part of what keeps us
发射探测器去很多不同的地方的原因之一
from sending probes to lots of different places in one trip:
在太空移动需要太多太沉的燃料了
Moving around just takes so much heavyfuel.
但是在20世纪80年代 科学家们发现了一个漏洞
But back in the 1980s, scientists found aloophole,
一个几乎不用任何燃料就可以在太阳系旅行的方法
a way of touring the solar system on almost no fuel at all.
它的名字叫做星际高速公路
It’s called the Interplanetary Superhighway.
在那时 在太阳系的天体之间移动
These days, moving between objects in the solar system,
像从地球轨道去往火星
like going from Earth-orbit to Mars,
通常需要一个叫做霍曼转移的理论
generally requires what’s calleda Hohmann transfer.
发射火箭后持续加速
You fire your rocket and speed up until your
直到绕地轨道大到
orbit around Earth gets so big that it crosses
与火星的绕日轨道交叉
Mars’s orbit around the Sun. Then,
然后 快经过火星时
once you pass near Mars,
火箭开启减速 然后
you use your rocket to slow down and
正式开始绕火星运行
officially begin to orbit the Red Planet.
所有的加速和减速
All that speeding up and slowing
都要燃烧很多燃料
down burns a lot of fuel,
但是霍曼转移是在太空中两个天体之间穿行的
but Hohmann transfers are one of the most efficient ways
最有效的方法之一 而且
of getting between any two bodies in space. Then,
引力的帮助让它更高效
there are also gravity assists, which can be even more efficient.
在这个理论中 一个太空船借助
In them, a craft speeds up by
不同星球的引力加速
using a different planet’s gravity to
像弹弓一样弹过 而不用燃烧太多燃料
slingshot past it without burning much fuel.
探测器离开地球的过程中会一直用这个方法
They’re used all the time to get probesfar from Earth.
但是如果飞船在引力的协助后
But if a spacecraft needs to orbit somewhere
需要围绕某天体运行
after a gravity assist,
它到达那里之后依然要减速 那么
it still has to slow down when it gets there. And,
同样 这需要很多燃料
again, that takes a lot of fuel.
所以在20世纪80年代 一些科学家换一种不同的方式处理这个问题
So in the 1980s, a few scientists tried approaching things a little differently.
通过把引力想成一种地形而不是一个弹弓
By thinking of gravity more like a landscapethan a slingshot,
他们偶然发现了星际高速公路
they stumbled upon the Interplanetary Superhighway.
探测器的出口和入口坡道是拉格朗日点:
Its entrance and exit ramps are Lagrange Points:
五个引力与旋转力平衡的点
Five regions where gravity and rotational forces balance.
它们存在于一个天体围绕另一个运行时
They exist whenever one body orbits another,
它们被有创造力地从L1命名到L5
and they’re creatively named L1 through L5.
如果你把宇宙飞船放置在一个拉格朗日点上
If you stick a spaceship at a Lagrange point,
它就会待在那里
it will stay there,
因为引力在任何一个方向都是平衡的
because gravity doesn’t pull it more in one direction than another.
但不是所有的拉格朗日点都是等价的
But not all Lagrange points are made equal.
有些点是稳定的
Some points are stable:
换句话说 如果你在那里然后稍微偏离一点点
In other words, if you’re there and you move away a bit,
引力就会把你拉回去
gravity tends to pull you back,
有点像一个在山谷底部的球
kind of like a ball at the bottom of a valley.
其他点是不稳定的
Other points are unstable:
如果你偏离一点点 引力会把你拉得更远
If you move away a little, gravity keeps pulling you farther out.
处于这些点上的飞船就像立在山顶上的球
Spacecraft at these points are like ballson a hilltop:
如果它们处在微妙的平衡中或由你抓着它们就会停在原地
They’ll stay if they’re delicately balanced or if you hold them,
但是最轻微的风就会使它们加速滚下山 通常的
but the slightest breeze will send them speeding downhill. Normally,
在太阳系穿行需要计算
getting around the solar system requires accounting
并航行在这些山和山谷中
for and navigating all these hills and valleys,
在沿途燃烧很多燃料
burning a bunch offuel along the way.
但是星际高速公路不只是处理这些拉格朗日点
But instead of just dealing with all theseLagrange points,
而是让这些点有效的运作起来
the Interplanetary Superhighway puts them to work. See,
对每个稳定的轨道都有五个拉格朗日点
there are five Lagrange points for everystable orbit,
就像月亮的绕地轨道 地球的环日轨道
the Moon around the Earth, the Earth around the Sun,
每一个土星卫星的环土星轨道
each of Saturn’s moons around Saturn,
凡是你能想起来的
you name it.
所以它们无处不在 虽然它们不是老在同一个位置
So they’re everywhere, although they aren’talways in the same place.
这些点往往伴随在质量较小物体的轨道周围
The points always follow the less massiveobject around its orbit,
创造不断变化的
and that creates a constantly changing landscape
太阳系中的引力山丘和山谷地形
of gravitational hills and valleys throughout the solar system.
换句话说 引力在太阳系中的分配
In other words, the distribution of gravitational forces
是随时间变化的:有时
in the solar system changes over time: Sometimes,
一个把你拉向太阳的点
a spot might be mostly pulled to the Sun,
有时是拉向一个行星的点
sometimes mostly to a planet,
有时 就是经过拉格朗日点时 二者都不是
and sometimes neither or both, when a Lagrangepoint passes by.
这个山丘和山谷的比喻帮助了我们所有人
The metaphor of hills and valleys just helps all of us,
专业和非专业的科学家们
professional and non-professional scientists,
去更好地了解了这个抽象的想法 偶尔
get a better grip on that abstractidea. Occasionally,
在太空中 有些山会通过附近的山甚至与之重叠
in space, some hills pass near each other or even overlap.
如果发生这样的情况 太空旅行会变得非常有效率
And when they do, space travel can get reallyefficient.
比如 如果你
For example, if you’re
在一个引力山和山谷重叠的地方
on a gravitational hill that overlaps a valley,
你就可以直接滚进去
you can just roll right down into it.
或者你在两个山顶叠加的地方
Or if you’re on one hilltop that overlaps another,
你就可以从一个顶点移动到另一个顶点
you can just move from summit to summit.
当不同轨道的拉格朗日点相互靠近时
When Lagrange points from different orbitsget near each other,
从一个点到另一个点就几乎不费力
it takes almost no effort to get from one to the next.
这就意味着 如果你愿意去等待合适的重叠部分
That means, if you’re willing to wait for the right overlaps,
你就可以在轨道之间自由跳跃 比如说
you can hop from orbit to orbit, say,
从地球到火星再到木星或者更远
from Earth to Mars to Jupiter and beyond,
却几乎不用燃料
with almost no fuel.
这就是星际高速公路背后的想法:
That’s the idea behind the Superhighway:
用这个不断变化的拉格朗日点网络
It uses this ever-evolving network of Lagrange points
让你自由地在轨道间穿梭 没有燃料的需求 官方的
to let you to travel between orbits practically for free, no fuel required. Officially,
所有这些在点与点之间的移动都叫做低能转移
all these moves between pointsare known as low-energy transfers,
它们已经被用在了几个航天任务里
and they have been used in a couple of missions.
其中一个最知名的就是
One of the better known ones was a
1991年对一个日本的月球探测器营救最后尝试的成功
successful last-ditch effort to save a Japanese lunar probe in 1991,
那时没有足够的燃料去以传统的方式营救这个任务 不幸的是
where there wasn’t enough fuel to salvage the mission the conventional way. Unfortunately,
不过 我们不能在每一个任务里
though, we can’t use thesetransfers for every mission,
因为有时需要数年甚至数千年
because it can sometimes take years or even millennia
拉格朗日点才能顺利的重叠
for Lagrange points to favorably overlap.
但如果我们愿意等
But if we were willing to wait,
我们可以向宇宙某处发射一个探测器
we could send a probe out somewhere in space,
它可以在那收集一段时间数据并等待着合适的重叠
where it could collect data for a while and wait for a good overlap. Then,
这样 当它出现时
when one popped up,
它可以滑到其他地方并收集数据直到下一个对准点出现
it could glide over and collect data somewhere else until another alignment appeared.
太空船几乎可以无限期地在太阳系穿行
The craft could wander through the solar systemalmost indefinitely,
检查任何一个和它距离足够近的物体
inspecting whatever happened to get close enough and
途中我们能发现很多东西 公认地
teaching us a lot along the way. Admittedly,
和我们目前的太空探索相比
it would be a pretty different type
它是非常不一样的一种类型
of space exploration than what we’re doing now,
但对于未来的长期任务 它会是很有前景的选择
but it could be a promising option for a future long-term mission.
这都多亏了星际高速公路
And it would all be thanks to the InterplanetarySuperhighway.
但如果我现在就想探索宇宙该怎么办?
But what if I want to explore the universenow?!
幸运的 我可以一直假装
Luckily I can always pretend to
是一个未来的宇航员
be an astronaut from the future
和这个Brilliant网站的测试一起星际旅行
with this Brilliant.org quiz on interstellar travel.
如果你喜欢这一集视频
If you liked this episode,
我想你会非常享受Brilliant的全部天文学课程
I think you’ll really enjoy the whole Astronomy course on Brilliant,
这个测试含有很多我们说过的
and this quiz addresses a lot of the challenges
太空旅行的挑战题目
of space travel we’ve been talking about.
现在Brilliant
Right now, our friends
为我们提供了头200名太空科学秀的观众
at Brilliant are offering the first 200 SciShow Space viewers that go to
brilliant.org/SciShowSpace年度优质订阅的八折优惠
brilliant.org/SciShowSpace a 20% discounton an annual premium subscription.
你可以锻炼你数学和科学的技能
You’ll sharpen your math and science skills,
它也许也可以帮助人类向在星际高速公路旅行更进一步 所以
and maybe help humanity get one step closer to traveling the interplanetary superhighway. So,
赶快行动吧!
get going!
先到先得哦!
Time’s a-wastin’!
[结尾音乐]
[ ♪ Outro ]

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视频概述

你知道宇宙飞船如何在用最少燃料的前提下最有效的航行吗?快来走进美妙的天体物理世界,来了解星际高速公路吧!

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视频来源

https://www.youtube.com/watch?v=1-6Str9V26g

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