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Space Elevator



 
 
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  #1  
Old June 26th 04, 02:47 AM
Big John
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Default Space Elevator

Scientist Sees Space Elevator in 15 Years

By CARL HARTMAN, Associated Press Writer

WASHINGTON - President Bush (news - web sites) wants to return to the
moon and put a man on Mars. But scientist Bradley C. Edwards has an
idea that's really out of this world: an elevator that climbs 62,000
miles into space.

Edwards thinks an initial version could be operating in 15 years, a
year earlier than Bush's 2020 timetable for a return to the moon. He
pegs the cost at $10 billion, a pittance compared with other space
endeavors.

"It's not new physics — nothing new has to be discovered, nothing new
has to be invented from scratch," he says. "If there are delays in
budget or delays in whatever, it could stretch, but 15 years is a
realistic estimate for when we could have one up."

Edwards is not just some guy with an idea. He's head of the space
elevator project at the Institute for Scientific Research in Fairmont,
W.Va. NASA (news - web sites) already has given it more than $500,000
to study the idea, and Congress has earmarked $2.5 million more.

"A lot of people at NASA are excited about the idea," said Robert
Casanova, director of the NASA Institute of Advanced Concepts in
Atlanta.

Edwards believes a space elevator offers a cheaper, safer form of
space travel that eventually could be used to carry explorers to the
planets.

Edwards' elevator would climb on a cable made of nanotubes — tiny
bundles of carbon atoms many times stronger than steel. The cable
would be about three feet wide and thinner than a piece of paper, but
capable of supporting a payload up to 13 tons.

The cable would be attached to a platform on the equator, off the
Pacific coast of South America where winds are calm, weather is good
and commercial airplane flights are few. The platform would be mobile
so the cable could be moved to get out of the path of orbiting
satellites.

David Brin, a science-fiction writer who formerly taught physics at
San Diego State University, believes the concept is solid but doubts
such an elevator could be operating by 2019.

"I have no doubt that our great-grandchildren will routinely use space
elevators," he said. "But it will take another generation to gather
the technologies needed."

Edwards' institute is holding a third annual conference on space
elevators in Washington starting Monday. A keynote speaker at the
three-day meeting will be John Mankins, NASA's manager of human and
robotics technology. Organizers say it will discuss technical
challenges and solutions and the economic feasibility of the elevator
proposal.

The space elevator is not a new idea. A Russian scientist, Konstantin
Tsiolkovsky, envisioned it a century ago. And Arthur C. Clarke's novel
"The Foundations of Paradise," published in 1979, talks of a space
elevator 24,000 miles high, and permanent colonies on the moon,
Mercury and Mars.

The difference now, Edwards said, is "we have a material that we can
use to actually build it."

He envisions launching sections of cable into space on rockets. A
"climber" — his version of an elevator car — would then be attached to
the cable and used to add more lengths of cable until eventually it
stretches down to the Earth. A counterweight would be attached to the
end in space.

Edwards likens the design to "spinning a ball on a string around your
head." The string is the cable and the ball on the end is a
counterweight. The Earth's rotation would keep the cable taut.

The elevator would be powered by photo cells that convert light into
electricity. A laser attached to the platform could be aimed at the
elevator to deliver the light, Edwards said.

Edwards said he probably needs about two more years of development on
the carbon nanotubes to obtain the strength needed. After that, he
believes work on the project can begin.

"The major obstacle is probably just politics or funding and those two
are the same thing," he said. "The technical, I don't think that's
really an issue anymore."
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Posted by

Big John

  #2  
Old June 26th 04, 05:02 AM
Ross Oliver
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Default

Big John wrote:
Scientist Sees Space Elevator in 15 Years

By CARL HARTMAN, Associated Press Writer

WASHINGTON - President Bush (news - web sites) wants to return to the
moon and put a man on Mars. But scientist Bradley C. Edwards has an
idea that's really out of this world: an elevator that climbs 62,000
miles into space.



The space elevator concept is "discovered" by all the non-SF-reading
journalists about once per decade. Hey, isn't the sunspot cycle
11 years long? Hmm.....

My favorite variation was describe in (IIRC) Scientific American
a while back. Rather than being attached to the ground, this
elevator would rotate in orbit like a huge two-armed windmill.
As one end descended into the upper atmosphere, about 50,000 ft
AGL, an aircraft would dock with the free end (hey, if they can
catch falling satellites...) and be hauled up into space. This
variant has the advantages needing no ground facilities, avoiding
terrestrial storms, and the capability of serving many different
points on the globe.

  #3  
Old June 26th 04, 06:28 AM
Felger Carbon
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"Big John" wrote in message
...

Arthur C. Clarke's novel
"The Foundations of Paradise," published in 1979, talks of a space
elevator 24,000 miles high, and permanent colonies on the moon,
Mercury and Mars.


"The Fountains of Paradise". Not Foundations.


  #4  
Old June 26th 04, 07:07 AM
Ron Wanttaja
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Space Elevators are obvious, but how does a Space Trim Tab work? :-)

Ron Wanttaja
  #5  
Old June 26th 04, 05:03 PM
Tim Ward
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"Ron Wanttaja" wrote in message
...
Space Elevators are obvious, but how does a Space Trim Tab work? :-)

Ron Wanttaja


I dunno, but this seems as good a time as any to bring up a stupid,
complicated idea of mine for access to space.

First, you should be familiar with the Kelly Aerospace idea of towing the
spaceship to altitude. If not, Google for "Eclipse project", NASA, and
perhaps F106.

They towed an idling F106 behind a C141 as a proof of concept project.

Second, you should be aware of the "payout winches" used to ground launch
hang gliders. These just pay the line out at a constant tension, rather
than reeling them in at a high rate of speed, as in sailplane launches.

So here's the scheme:
You build a tow plane about the size of a 747. The payout winch is mounted
such that it "pays out" from the CG of the airplane, on top. You have
somewhere around 100,000 lbs of Vectran tow rope (several tens of
kilometers) on the payout device. This is within the cargo capability of a
747, though you may want to throw on a couple of extra engines because of
the additional drag.

The spacecraft has a CG hook on the bottom.

You take off, and climb as high as you can, while paying out the tow line.
The spacecraft pilot basically controls the pay out. Pitch up, and a little
more line pays out. Pitch down, and it stops.

If the spacecraft can maintain a 45 degree angle behind the towplane, it
will be 70% of the towrope's length higher than the towplane.

At some point, the true airspeed of the tow plane will not provide enough
airspeed for the spacecraft to continue to climb. So the towplane starts to
turn, and the spacecraft maneuvers to the outside of the turn. Now it's
just like playing "crack the whip". The air-breathing booster is down in
the (relatively speaking) thick atmosphere at 50,000 feet, while the
spacecraft is above most of the atmosphere at say, 100,000 feet.

That's when the spacecraft releases and fires its rockets.
Because the atmosphere is so much thinner, and the spacecraft is going
faster than it would be at lower altitudes, the increase in peak altitude
achievable should be much higher than just the 50,000 ft altitude difference
between the tow plane and the spacecraft.

After the spacecraft releases, the towplane also releases the towline, and
it descends under a parachute, separately.

There, I feel better.

Tim Ward




  #6  
Old June 26th 04, 07:18 PM
external usenet poster
 
Posts: n/a
Default

You should post this on sci.space.tech

It is a moderated news group and the signal to nise ration is high.





im Ward" wrote:


"Ron Wanttaja" wrote in message
.. .
Space Elevators are obvious, but how does a Space Trim Tab work? :-)

Ron Wanttaja


I dunno, but this seems as good a time as any to bring up a stupid,
complicated idea of mine for access to space.

First, you should be familiar with the Kelly Aerospace idea of towing the
spaceship to altitude. If not, Google for "Eclipse project", NASA, and
perhaps F106.

They towed an idling F106 behind a C141 as a proof of concept project.

Second, you should be aware of the "payout winches" used to ground launch
hang gliders. These just pay the line out at a constant tension, rather
than reeling them in at a high rate of speed, as in sailplane launches.

So here's the scheme:
You build a tow plane about the size of a 747. The payout winch is mounted
such that it "pays out" from the CG of the airplane, on top. You have
somewhere around 100,000 lbs of Vectran tow rope (several tens of
kilometers) on the payout device. This is within the cargo capability of a
747, though you may want to throw on a couple of extra engines because of
the additional drag.

The spacecraft has a CG hook on the bottom.

You take off, and climb as high as you can, while paying out the tow line.
The spacecraft pilot basically controls the pay out. Pitch up, and a little
more line pays out. Pitch down, and it stops.

If the spacecraft can maintain a 45 degree angle behind the towplane, it
will be 70% of the towrope's length higher than the towplane.

At some point, the true airspeed of the tow plane will not provide enough
airspeed for the spacecraft to continue to climb. So the towplane starts to
turn, and the spacecraft maneuvers to the outside of the turn. Now it's
just like playing "crack the whip". The air-breathing booster is down in
the (relatively speaking) thick atmosphere at 50,000 feet, while the
spacecraft is above most of the atmosphere at say, 100,000 feet.

That's when the spacecraft releases and fires its rockets.
Because the atmosphere is so much thinner, and the spacecraft is going
faster than it would be at lower altitudes, the increase in peak altitude
achievable should be much higher than just the 50,000 ft altitude difference
between the tow plane and the spacecraft.

After the spacecraft releases, the towplane also releases the towline, and
it descends under a parachute, separately.

There, I feel better.

Tim Ward




  #7  
Old June 26th 04, 11:34 PM
Howard Eisenhauer
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Posts: n/a
Default

On Fri, 25 Jun 2004 22:42:15 -0700, Richard Riley
wrote:

On Fri, 25 Jun 2004 20:47:03 -0500, Big John
wrote:

:Scientist Sees Space Elevator in 15 Years
:
:By CARL HARTMAN, Associated Press Writer
:
:WASHINGTON - President Bush (news - web sites) wants to return to the
:moon and put a man on Mars. But scientist Bradley C. Edwards has an
:idea that's really out of this world: an elevator that climbs 62,000
:miles into space.

OK, so you use a whole lotta solar power beamed at your cart to climb
62,000 miles straight up (without becoming a crispy critter, but
that's another topic).

Where are you going to get the mass and energy to accelerate yourself
laterally to reach orbital velocity? Aren't you just going to
decelerate the beanstalk and send it whipping to the west as the earth
rotates beneath you, winding the beanstalk along the equator like an
earth sized yo-yo?



At 24,000 mile you're at geosynchronis orbit, ready to float free. If
you want an orbit lower down you just burn a little rocket fuel (that
you brought up with you) to slow down & drop lower.

The other 38000 miles of line wants to pull away from the Earth so
acts as a counter weight keeping the whole thing pulling straight up.
If you keep going past the 24,000 mark before cutting loose you start
picking up the velocity you need to get to the Moon, as well as many
other fun spots around the system .

Any deflection caused by sending payloads up gets cancelled out by
stuff coming back down, i.e "My Parents Went to Jupiter & All They Got
Me Was This Cheap T-Shirt" x 10-6.

H.
  #8  
Old June 26th 04, 11:47 PM
Anthony
external usenet poster
 
Posts: n/a
Default


"Tim Ward" wrote in message
...

"Ron Wanttaja" wrote in message
...
Space Elevators are obvious, but how does a Space Trim Tab work? :-)

Ron Wanttaja


I dunno, but this seems as good a time as any to bring up a stupid,
complicated idea of mine for access to space.

First, you should be familiar with the Kelly Aerospace idea of towing the
spaceship to altitude. If not, Google for "Eclipse project", NASA, and
perhaps F106.


Snip

Why not resurrect project Orion and ride the wake of nuclear blasts into
space.

Tony


  #9  
Old June 27th 04, 12:02 AM
Tim Ward
external usenet poster
 
Posts: n/a
Default


"Anthony" wrote in message
...

"Tim Ward" wrote in message
...

"Ron Wanttaja" wrote in message
...
Space Elevators are obvious, but how does a Space Trim Tab work? :-)

Ron Wanttaja


I dunno, but this seems as good a time as any to bring up a stupid,
complicated idea of mine for access to space.

First, you should be familiar with the Kelly Aerospace idea of towing

the
spaceship to altitude. If not, Google for "Eclipse project", NASA, and
perhaps F106.


Snip

Why not resurrect project Orion and ride the wake of nuclear blasts into
space.

Tony


Cost?
Even if the hardware was free, the infrastructure to support a surface
launch would be awfully expensive. I know Niven & Pournelle had something
like that in Lucifer's Hammer, but that was an effort to throw off alien
conquerors.

I thought Orion was space-to-space transportation.

The system I've proposed wouldn't be cheap, but it could conceivably take
off and land from a regular airport.

Tim Ward


  #10  
Old June 27th 04, 12:15 AM
Bill Daniels
external usenet poster
 
Posts: n/a
Default


"Howard Eisenhauer" wrote in message
news
On Fri, 25 Jun 2004 22:42:15 -0700, Richard Riley
wrote:

On Fri, 25 Jun 2004 20:47:03 -0500, Big John
wrote:

:Scientist Sees Space Elevator in 15 Years
:
:By CARL HARTMAN, Associated Press Writer
:
:WASHINGTON - President Bush (news - web sites) wants to return to the
:moon and put a man on Mars. But scientist Bradley C. Edwards has an
:idea that's really out of this world: an elevator that climbs 62,000
:miles into space.

OK, so you use a whole lotta solar power beamed at your cart to climb
62,000 miles straight up (without becoming a crispy critter, but
that's another topic).

Where are you going to get the mass and energy to accelerate yourself
laterally to reach orbital velocity? Aren't you just going to
decelerate the beanstalk and send it whipping to the west as the earth
rotates beneath you, winding the beanstalk along the equator like an
earth sized yo-yo?



At 24,000 mile you're at geosynchronis orbit, ready to float free. If
you want an orbit lower down you just burn a little rocket fuel (that
you brought up with you) to slow down & drop lower.

The other 38000 miles of line wants to pull away from the Earth so
acts as a counter weight keeping the whole thing pulling straight up.
If you keep going past the 24,000 mark before cutting loose you start
picking up the velocity you need to get to the Moon, as well as many
other fun spots around the system .

Any deflection caused by sending payloads up gets cancelled out by
stuff coming back down, i.e "My Parents Went to Jupiter & All They Got
Me Was This Cheap T-Shirt" x 10-6.

H.


This space elevator thing is elegant in a Newtonian sort of way but I
suspect that there is a lot more to it that hasn't been completely thought
out.

They say put it on the equator where the winds are low. Well, they are low
most of the time but there is always the occasional typhoon.

Then there are the electrical effects. A carbon nanotube cable will conduct
electricity pretty well. Some claim it's a room temperature superconductor
candidate. A tropical lightning strike can be several million amps and this
cable will be a pretty good lightning rod. There's the induced voltages
too. The normal atmospheric potential gradient is several million volts per
meter.

What about tidal effects? Twice each day the Moons gravity will pull on the
structure.

Bill Daniels

 




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