February 17, 2004
A: FROM MENTOR ANDREA GUNTHER IN WA
I don't know much about the space elevator, but your
qustion has been out there for a while so I thought
I'd tell you what I know. I think the point is to
move objects further from the pull of earth's gravity.
As the object moves up the cable it would gain
momentum. I understand that the greatest challenge is
the material for the cable. It must be very strong
without being so huge that its own weight would break
the cable. The centripital force of an object at the
end of the cable would keep the cable in tension and
straight off the surface of the earth. Even if the
elevator never gets built, the material reseach being
done to support will be used in other industries.
Here is a link that has some easy to read technical
information.
http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html
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February 11, 2004
A: FROM MENTOR LEE PELLEGRINO-GENSEY IN NJ
Here's a web site explaining the concept of space elevators and Legrange
points:
http://www.airspacemag.com/ASM/Mag/Index/2004/DJ/100Y.html
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A: FROM MENTOR JOAN LUSK IN RI

I'm not sure I believe this, but there are people who think it can be done. Nanotechnology in general and making nanotubes is clearly a very active research area nowadays, so the necessary stong materials may be feasible. It's still hard for me to believe that the top of the cable could be in orbit like a satellite and support the rest of the cable, though - maybe it is just "simple physics." Here's a site and a long quote from it:
http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html

For a space elevator to function, a cable with one end attached to the Earth's surface stretches upwards, reaching beyond geosynchronous orbit, at 21,700 miles (35,000-kilometer altitude). After that, simple physics takes charge.

The competing forces of gravity at the lower end and outward centripetal acceleration at the farther end keep the cable under tension. The cable remains stationary over a single position on Earth. This cable, once in position, can be scaled from Earth by mechanical means, right into Earth orbit. An object released at the cable's far end would have sufficient energy to escape from the gravity tug of our home planet and travel to neighboring the moon or to more distant interplanetary targets.

Putting physics aside the toughest challenge has been finding a super-strong cable material. "That's what has kept this idea in science fiction for 40 years," Edwards said. But the right stuff in terms of cable material is no longer thought of as "unobtainium", he said.

The answer is carbon-nanotube-composite ribbon. Small fibers of the material are set down side-by-side, then interconnected to form a growing ribbon.

Stronger than steel

The hurdle to date, Edwards said, has been the commercial fabrication of carbon nanotubes. Both U.S. and Japanese firms, among others, are ramping up production of carbon nanotubes, with tons of this now exotic matter soon to be available. "That quantity of material is going to be around well before five years time. It's not going to take long," he said.

Given the far stronger-than-steel ribbon of carbon nanotubes, a space elevator could be up within a decade. "There's no real serious stumbling block to this," Edwards explained.

"The making of carbon nanotubes is moving very quick," said Hayam Benaroya, a professor in the Department of Mechanical and Aerospace Engineering at Rutgers in Piscataway, New Jersey. "We're moving from the scientific stage of just developing them to actual commercial entities producing them in ton-like quantities," he said.