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Space Elevator: Momentum Building
By Leonard David
Senior Space Writer
posted: 07:00 am ET
29 June 2004



Leading experts are meeting this week to take a longing look at the
idea of a space elevator. The idea is a stretch, no doubt, with plenty
of work to do before travelers have push-button, top floor access to
space.

For one, what's needed, advocates explain, is a super-tough ribbon
that does an about face in thinking. It hangs from the ground and
falls into the sky -- thanks to the Earth's spin and centripetal
force.

Anchored in space a ribbon 62,000 miles (100,000 kilometers) long
would be made of carbon nanotubes. A "climber" would haul cargo, as
well as passenger modules up and down the length of ribbon. Those are
the basics. Of course, money is a key lubricant in this high-wire
balancing act of technology.

At the third annual international conference on the space elevator
being held in Washington, D.C., scientists and engineers are tackling
hurdles that must be overcome for the concept to, quite literally, get
off the ground.

Challenges ahead

"It's a mega project…things are moving about as quickly and as well as
could be expected," said Bradley Edwards, Director of Research for the
Institute for Scientific Research (ISR), based in Fairmont, West
Virginia. He is a leading authority on the space elevator concept, and
is moderator for this week's event.

Edwards is quick to run down what's up on the space elevator
challenges, from carbon nanotube technology, power beaming, climber
hardware to space debris impacts on the ribbon, health and safety
issues, as well as cost, politics and regulations.

At this week's gathering, leading scientists delving into carbon
nanotubes are detailing the fast-paced nature of their work in this
arena. Different methods of producing carbon nanotubes are moving
forward, even to the point of a new process that spins the material in
similar fashion to how rope is made, Edwards told SPACE.com.

The discovery of carbon nanotubes and the ongoing development to form
them into a composite material is central to space elevator viability
being achieved in the coming years.

Major advancements are underway in carbon nanotubes, Edwards said.
That goes for competitive production ideas, as well as churning them
out in ever-stronger batches and at costs far cheaper than before.
Purchasing grams of the material in the past has turned into buying
kilograms today, and for a greatly reduced price tag, he said.

Space elevator 101

Blue-sky thinkers like Edwards envision the space elevator as a
revolutionary way of getting from Earth into space. The primary system
is a ribbon attached at one end to Earth on a floating platform
located in the equatorial Pacific Ocean. The other end of the ribbon
is in space, beyond geosynchronous orbit.

Once operational a space elevator could ferry satellites, spaceships,
and various structures into space using electric lifts clamped to the
ribbon. Research points to a space elevator capable of lifting
five-ton payloads every day to all Earth orbits, the Moon, Mars, Venus
or the asteroids - in 15 years after formal go-ahead.

The first space elevator would reduce lift costs immediately and
drastically, as compared to current launch costs. Additional and
larger elevators, built utilizing the initial design, would allow
large-scale activities in space and reduce lift costs even more.

Admittedly, years of research are required to turn this pipedream into
actual space hardware. Nevertheless, major organizations are taking
the notion seriously. That is clear from the list of sponsors for this
week's meeting: Los Alamos National Laboratory, NASA's Marshall Space
Flight Center, NASA Institute for Advanced Concepts, as well as the
National Space Society.

"There's a broad range of issues…but we're trying to hit the biggest
issues we can," Edwards said.

Straightforward exploration

Being on top of the space elevator has its downside, Edwards noted. "I
get a lot of ‘this is crazy' kind of comment," he said.

But remember the early mariners who dared to build ships that sailed
around the globe. Recall how going to the Moon was thought impossible,
expressed by well-known experts at the time, Edwards countered.

"People have to take the time to look at the engineering that's been
done," Edwards explained, "then make an informed decision. That's what
we've been pushing."

Edwards said NASA's new reach back to the Moon, onward to Mars and
beyond would become a very clear-cut undertaking – given high-strength
material to fabricate a space elevator.

"The risk of a Challenger or Columbia shuttle tragedy is basically
removed. You don't have the large energy transfer type events of a
rocket launch or reentry. No need for heavy-lift vehicles. You can
eliminate a lot of the other development risks," Edwards concluded.
"The whole space exploration program could be very straightforward and
become successful pretty quick."

Is that 62,000 mile figure a typo or intended?

a 62 mile tower is probably not much of a moment problem
(compared to 8000 mile planet diameter).

But 62,000? There's a tail wagging the dog!

In article ,
Richard Lamb wrote:

Is that 62,000 mile figure a typo or intended?

It's intended (that's the approximate altitude of geosynchronous orbit).

a 62 mile tower is probably not much of a moment problem
(compared to 8000 mile planet diameter).

But 62,000? There's a tail wagging the dog!

I'm not sure what a moment problem is, but a space elevator doesn't
violate any fundamental laws of physics. (But note that it's not really
a tower, i.e. a compression structure; it's in tension.)

Best,
- Joe

,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| http://www.macwebdir.com |
`------------------------------------------------------------------'

"Richard Lamb" wrote in message ...

Is that 62,000 mile figure a typo or intended?

Yes. It's a space elevator, not just some high tower reaching into
airless space. It's being held in place by centrifugal force, which
starts pulling outward at 36,000km, so the elevator must go out fur-
ther. The further out it stretches the further you can launch cargo
into space by simply letting go, BTW.

a 62 mile tower is probably not much of a moment problem
(compared to 8000 mile planet diameter).

But 62,000? There's a tail wagging the dog!

It's the Earth's rotation keeping the thing taut, so as far as dog/
tail analogies go I'd say it's very much the dog (Earth) wagging (ro-
tating) the tail (elevator).



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('__` screams for help and focus on the bigger picture." '__`)
//6(6; ©OOL mmiv :^)^\\
`\_-/ http://home.t-online.de/home/ulrich....lmann/redbaron \-_/'

Joe Strout wrote in news:joe-
:

In article ,
Richard Lamb wrote:

Is that 62,000 mile figure a typo or intended?

It's intended (that's the approximate altitude of geosynchronous orbit).

Actually, it's more than twice the altitude of geosynchronous orbit.
Remember, the elevator must extend below *and above* GEO, such that the
center of gravity is above GEO.

a 62 mile tower is probably not much of a moment problem
(compared to 8000 mile planet diameter).

But 62,000? There's a tail wagging the dog!

I'm not sure what a moment problem is, but a space elevator doesn't
violate any fundamental laws of physics. (But note that it's not really
a tower, i.e. a compression structure; it's in tension.)

And it's not a "tail wagging the dog", either - its mass is miniscule
compared to the Earth. I'm not quite sure what Richard was getting at with
that remark.

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

Richard Lamb wrote:
Is that 62,000 mile figure a typo or intended?

a 62 mile tower is probably not much of a moment problem
(compared to 8000 mile planet diameter).

But 62,000? There's a tail wagging the dog!

62000, yes.
It's not a tower, but a rope.
It's held up by the tension of the far end spinning faster than
the orbit it 'wants' to be in.

62000 is not an exact figure, but is in the ballpark, exact length
depends on a few assumptions.

"Jorge R. Frank" wrote:

Joe Strout wrote in news:joe-
:

In article ,
Richard Lamb wrote:

Is that 62,000 mile figure a typo or intended?

It's intended (that's the approximate altitude of geosynchronous orbit).

Actually, it's more than twice the altitude of geosynchronous orbit.
Remember, the elevator must extend below *and above* GEO, such that the
center of gravity is above GEO.

a 62 mile tower is probably not much of a moment problem
(compared to 8000 mile planet diameter).

But 62,000? There's a tail wagging the dog!

I'm not sure what a moment problem is, but a space elevator doesn't
violate any fundamental laws of physics. (But note that it's not really
a tower, i.e. a compression structure; it's in tension.)

And it's not a "tail wagging the dog", either - its mass is miniscule
compared to the Earth. I'm not quite sure what Richard was getting at with
that remark.

--
JRF


Sorry Jorg, but it really is. At least if it's attached to the Earth.

Even a fairly light weight times a humongous arm = massive moments.
And this things' arm is about 7.75 times the diameter of earth.

To help visualize what I'm talking about, take a golf ball and stick
a 9 or 10 inch long piece of very thin stiff wire on one side.

Now spin it. Or try to...

Guys, this isn't even rocket science, just basic aircraft style
weight and balance applied to a rotating body.



Richard Lamb

Richard Lamb wrote in
:

"Jorge R. Frank" wrote:

And it's not a "tail wagging the dog", either - its mass is miniscule
compared to the Earth. I'm not quite sure what Richard was getting at
with that remark.

Sorry Jorg, but it really is. At least if it's attached to the Earth.

Even a fairly light weight times a humongous arm = massive moments.
And this things' arm is about 7.75 times the diameter of earth.

To help visualize what I'm talking about, take a golf ball and stick
a 9 or 10 inch long piece of very thin stiff wire on one side.

Now spin it. Or try to...

Bad analogy. Take a bowling ball, then attach a long hair to it. Shoot,
even a hair is probably orders of magnitude too massive.

Guys, this isn't even rocket science, just basic aircraft style
weight and balance applied to a rotating body.

You're right. And you just flunked, due to your inability to comprehend the
magnitude of the numbers under discussion.


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

Ian! Et Tu?

I've read you and Jorg for quite a while now, and you guys
have always had an excellent command of the scientific stuff.

Sure, I understand the idea that centrifugal force is holding
the thing 'up'. That is NOT what I'm questioning.

While the mass is very small compared to the mass of the earth,
the arm (length) is huge compared to the diameter of the earth.

I can't work out the numbers because I have no way to even
fantasize what the mass might be.

Anybody want to posit a Scientific Wild Assed Guess as to the
mass involved?

Richard Lamb

"Jorge R. Frank" wrote:

Richard Lamb wrote in
:

"Jorge R. Frank" wrote:

And it's not a "tail wagging the dog", either - its mass is miniscule
compared to the Earth. I'm not quite sure what Richard was getting at
with that remark.

Sorry Jorg, but it really is. At least if it's attached to the Earth.

Even a fairly light weight times a humongous arm = massive moments.
And this things' arm is about 7.75 times the diameter of earth.

To help visualize what I'm talking about, take a golf ball and stick
a 9 or 10 inch long piece of very thin stiff wire on one side.

Now spin it. Or try to...

Bad analogy. Take a bowling ball, then attach a long hair to it. Shoot,
even a hair is probably orders of magnitude too massive.

Guys, this isn't even rocket science, just basic aircraft style
weight and balance applied to a rotating body.

You're right. And you just flunked, due to your inability to comprehend the
magnitude of the numbers under discussion.

--
JRF


If I was being snotty, then I deserved that and I apologize.

I certainly didn't mean it that way.

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