节目资讯
刊物:空中英语教室
日期:2014-02-18
难易度:Medium
关键字:orbit, potential, realm, disbelief, tether, breakthrough, carbon nanotube
Hello, everyone. My name is Gabe.
And I'm Carolyn.
And welcome to Studio Classroom.
Your English will improve today.
Now, have you ever wanted to travel into space?
Carolyn, do you want to travel to space?
Well, it does seem interesting, but there's a big problem.
I don't have enough money.
Hmm, that is a big problem.
But it doesn't have to be one.
If scientists succeed in creating a space elevator, it will be a thousand times
cheaper than taking a rocket to the cosmos.
Well, what are they waiting for?
Well, they need a super-strong material to create the cable for the elevator.
Friends, open up your magazine and let's continue with the first section of
today's lesson, The Space Elevator, Searching for a super-strong material.
The Space Elevator.
Searching for a super-strong material.
The space elevator could be built using current technology with one exception:
the ribbon!
The ribbon required for the space elevator must be much stronger than steel yet
very lightweight.
It must act like a tether, holding firmly to the Earth while fastened to an
object floating in orbit.
A possible breakthrough.
The discovery of carbon nanotubes in 1991 was seen as a potential step toward
developing the ribbon.
Since carbon nanotubes are up to 100 times stronger than steel, they would make
the ribbon strong enough in theory.
Hi, everyone. I'm Michelle.
(Chinese).
Thanks, Michelle.
So we are in the search for a super-strong material, as our lesson says, a
material strong enough to take us from here to outer space.
Now sometimes we use the word super to mean really, really or extremely.
Like for instance, you might have a classmate that is really smart.
You could say he is super smart.
Or you have a car that you can drive really fast.
You are driving super fast.
Some planes fly at super speeds.
Maybe your friend has the opposite problem.
He is really slow at getting ready.
You might say: Come on, let's go! You're super slow.
And we learn that scientists are looking for a super-strong material to take us
up into space.
The space elevator could be built using current technology with one exception:
the ribbon.
That's right.
Now if you remember, it's not an actual ribbon like this because most ribbons
are too weak, but you might use it, and it might look like a ribbon.
Well, let's take a look at that phrase there: with one exception.
We have all the technology we need except one thing.
That is the exception.
Let's use that phrase in other ways.
OK. You are allowed to bring anything into this room with two exceptions: food
and drinks.
Right. So no food or drinks are allowed.
Or your teacher says: There's no talking during this test with one exception
that you are talking to me.
So you can't talk except with your teacher.
Well, just how strong must this ribbon be that will take cars into space?
We read it must be much stronger than steel yet very lightweight.
Well, what's stronger than steel?
Good question.
Very few things are stronger than steel.
Before we get into that, though, let's take a trip to the Grammar Gym to see
what Liz has to say about this sentence.
Welcome to the Grammar Gym, friends.
My name is Liz.
And I'm so glad you can join me here for today's Grammar Tip.
Speaking of Grammar Tip, here's today's sentence:
The ribbon required for the space elevator must be much stronger than steel yet
very lightweight.
Our focus today is on the sentence pattern:
[something] must be [adjective 1] yet [adjective 2].
This sentence pattern isn't very complicated, but it's very useful when you want
to describe how something has to have a certain quality,
but it also needs to have another quality that may seem like an opposite to the
first quality.
So in today's sentence, the ribbon for the space elevator must be stronger than
steel, but this ribbon needs to also be lightweight.
Usually people don't think of something being stronger than steel as being
lightweight.
But for the space elevator ribbon, these qualities are necessary.
OK. Here are some other examples.
This is an urgent assignment, and whoever does the job must be fast yet very
detailed.
Or: The supplies we buy must be very good quality yet inexpensive because we
have a tight budget.
That's all the time we have for today.
Be sure to check out today's Grammar Tip section in your Studio Classroom
magazine for more example sentences.
This is Liz from the Grammar Gym.
I'll see you next time.
Thanks, Liz.
So the ribbon for the space elevator needs to be lightweight, so not heavy, but
also super strong.
What else must this material be?
Well, we read it must act like a tether, holding firmly to the Earth while
fastened to an object floating in orbit.
Now let's talk about that idea for a moment.
A tether is like a rope that is tied onto one end to something moveable and onto
the other end that something... to something that stays in one place.
Of course this tether connecting the Earth to an object in space will be taut,
not loose.
There will probably be the same kind of tension that you see in this picture of
this rope.
But... so that the tether or ribbon needs to be very strong indeed.
Yes. And it will hold firmly to the Earth while fastened or connected strongly
to an object floating in orbit.
Now "orbit" can be a noun or a verb.
It's a noun phrase here.
Many things are in orbit around the Earth.
Planets are in orbit around the sun.
And as a verb, you would say the satellite is orbiting the Earth.
Or the planets orbit the sun; the Moon orbits Earth.
And if something is in orbit around the Earth, rotating at the same speed as
Earth, it will act kind of like a yo-yo on a string.
This is how the space elevator is supposed to work.
Well, there could be a possible breakthrough, as we read on here.
People have discovered carbon nanotubes and found them to be very strong.
And as you can guess, carbon nanotubes are tiny tubes made of carbon.
Carbon forms super-strong bonds with itself.
Hey, do you know what kind of material is made of carbon?
Diamonds!
Diamonds are really strong rocks, the strongest rocks on Earth.
So you can imagine that a material made of carbon would be a good thing to use
as a ribbon for the space elevator.
Yes.
Now yesterday we showed a video about the space elevator.
If you missed it, that's OK.
Let's take a look at it right now.
The space elevator, in simplest terms, is a ribbon.
One end attached to Earth, the other end is attached to a counterweight in outer
space.
The rotation of the Earth throws the counterweight on the ribbon outward,
keeping the ribbon taut.
Made from an advanced carbon nanotube composite material 30 times stronger than
steel,
the ribbon is 3 feet wide, thinner than a sheet of paper and 62,000 miles long.
Vehicles weighing up to 20 tons then climb the ribbon from Earth to outer space.
Simple electric motors hold the climbers upward with drive-treads gripping the
ribbon.
Power is supplied from a ground station in the form of a laser beam, which is
converted to electricity by the climber's photovoltaic array.
Located in the eastern Pacific Ocean, the anchor station is similar to a
floating oil drilling platform.
Additional platforms house the laser power beaming stations, allowing for power
to drive several climbers up the ribbon at once.
By using the outer end of the ribbon as a slingshot, it will be possible to
throw large payloads to destinations such as the Moon, Mars, Venus and beyond.
With cheap and frequent access to space a reality, mankind will be free to
pursue our destiny by finding a ribbon to the stars.