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It's hard to get to space
As much as we all wish there were an easy,
and affordable way to see our planet floating in the dark
Right now, the only way is to become an astronaut or a billionare
But there is a concept that might make it possible
-while serving as the starting point for the exploration of the universe-
The space elevator
How exactly does it work?
To understand how a space elevator will get us into space
We must first understand what an orbit is
Being in orbit basically means falling towards something,
but moving fast enough to miss
If you throw a ball on earth it makes an arch through the air,
and then hits the ground
In space, gravity makes you move much the same way,
but if you move sideways fast enough
the curvature of the earth makes the ground fall away beneath you
as fast as gravity pulls you towards it
So, to enter Earth's orbit rockets have to go up
and sideways fast
By contrast, a space elevator taps into energy from Earth's rotation
to get the cargo going fast
Imagine a child spinning a toy on a rope with an ant on the child's hand
As the ant climbs out along the rope
it starts to move faster and faster as it ascends
Compared to rockets, with cargo launched on an elevator
you only need to provide the energy to go up
Fast sideways movement comes free with the Earth's rotation
But the space elevator would without a doubt
be the single largest and most expensive structure ever built by humans
So, is it worth it?
It all comes down to costs
Rockets burn a huge amount of rocket fuel
just to get a small amount of cargo into space
At current prices, it costs about $20,000 to put one kilogram of payload into space
that's $1.3 million dollars for the average human
$40 million dollars for your car
billions for an international space station
This immense cost is one of the major limitations of human spaceflight
Even with advancing technology,
this cost isn't likely to be comparable with the price of an airline ticket anytime soon
A space elevator would solve this problem
After construction,
a space elevator is projected to reduce the cost one hundredfold to $200 per kilogram
If an inexpensive space elevator costs 20 billion dollars,
then we'll recoup our losses after launching only one million tons
Close to the weight of two international space stations
So what would a space elevator look like in real life?
A space elevator has four major components:
the tether, anchor, counterweight and climber
The elevator part of the space elevator is the tether and the climber
It extends from the surface of the Earth to space
The climber is like a conventional elevator carriage
A chamber that works its way up and down the tether
At the base would be an anchor
pinning the tether to the Earth along with a port for climbers
At the top is the counterweight which holds up the tether
The tether is held tight like a rope
and supported from above by the tension from the counterweight
Located higher than 36,000 kilometers above the Earth's surface
At the counterweight could be a space station,
a launching point for all missions from the spaceport elevator
But can we actually build one?
It's hard to say
The biggest challenge is the tether
It needs to be light, affordable
and more stable than any material we can produce right now
There are promising materials like graphene and diamond nanothreads,
but even they may not be strong enough
And aside from being incredibly strong,
the tether would also have to withstand atmospheric corrosion, radiation
and micrometeorite and debris impacts
Additionally, it takes several days to climb the elevator
How do we power the climber?
It requires a lot of energy to go up
Do we need a nuclear reactor on our elevator carriage?
Or do we beam it power from the ground with a super powered laser?
And where do we get the raw materials for a 36,000-kilometer-long tether?
Do we make it on Earth and launch it into space?
Or do we make it in space and lower it down to the Earth?
Could asteroid mining be the answer?
Put simply, there are still some major technological hurdles to overcome
And a space elevator is not without risk
Should the tether break, it would collapse in spectacular style
If it breaks near the anchor
the force exerted by the counterweight will cause the entire elevator to rise up
ascending into space
Should it break near the counterweight
the tether will fall,
wrapping around the world and whipping the end off
The resulting debris in orbit could pose serious problems to future spaceflight
If we build a space elevator on Earth, we have to do it right the first time
For these reasons some experts have proposed first building
a space elevator on the Moon
The Moon's gravity is much weaker than the Earth's
so a flimsier but existing material like kevlar
could serve as a tether
Even with all these challenges,
the payoff of having a working space elevator would be immense
It might be the first step to truly becoming a space-faring civilization
Maybe we will never build a space elevator,
but in trying to do so we might learn an awful lot
And when it comes to the exploration of the universe,
there can't be too many dreams of a glorious future
Subtitles by the Amara.org community
コツ:単語をクリックしてすぐ意味を調べられます!

読み込み中…

宇宙エレベータ―空想科学か人類の未来か(Space Elevator – Science Fiction or the Future of Mankind?)

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mommy 2016 年 4 月 12 日 に公開
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