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The Space Elevator Comes Closer to Reality

Discussion in 'Tech, Gadgets & Science Forum' started by E=mcsquared, Jul 12, 2010.

  1. E=mcsquared

    E=mcsquared JF-Expert Member

    Jul 12, 2010
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    ALBUQUERQUE, NEW MEXICO -- Make way for the ultimate high-rise project: the space elevator. Long viewed as science fiction "imagineering", researchers are gathering momentum in their pursuit to propel this uplifting concept into actuality.
    Still, the mental picture needed to grasp the elevator to space ideaÂ…well, you can't be weak of mind.
    Forget the roar of rocketry and those bone jarring liftoffs, the elevator would be a smooth 62,000-mile (100,000-kilometer) ride up a long cable. Payloads can shimmy up the Earth-to-space cable, experiencing no large launch forces, slowly climbing from one atmosphere to a vacuum.
    Earth orbit, the Moon, Mars, Venus, the asteroids and beyond - they are routinely accessible via the space elevator. And for all its promise and grandeur, this mega-project is made practical by the tiniest of technologies - carbon nanotubes.
    Seen as an engineering undertaking for the opening decades of the 21st century, the space elevator proposal was highlighted here during the 2002 Space and Robotics Conferences, held March 17-21, and sponsored by the Aerospace Division of the American Society of Civil Engineers.
    Thought experiment
    Science fiction writers have been deploying space elevators for years.
    Space visionary, Arthur Clarke, centered his novel of the late 1970s, The Fountains of Paradise, on the notion. Also, among other writers, Kim Stanley-Robinson's Red Mars noted the soaring splendor of an elevator to space. Furthermore, the scheme has bounced around technical journals for decades. Some call it a "thought experiment", but others point out that space exploration B.C. -- "Before Cable" -- will pale contrasted to what's possible within ten to fifteen years.
    "Even though the challenges to bring the space elevator to reality are substantial, there are no physical or economic reasons why it can't be built in our lifetime." That's the matter-of-fact feeling of physicist, Bradley Edwards of Eureka Scientific in Berkeley, California, but carrying out heavy lifting design work in Seattle, Washington.
    Edwards told that he's been wrapped up in space elevator work for some three years, supported by grants from NASA's Institute for Advanced Concepts (NIAC) program. "I'm convinced that the space elevator is practical and doable. In 12 years, we could be launching tons of payload every three days, at just a little over a couple hundred dollars a pound," he said.
    "In 15 years we could have a dozen cables running full steam putting 50 tons in space every day for even less, including upper middle class individuals wanting a joyride into space. Now I just need the $5 billion, Edwards added.
    And so it grows
    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.
    "Perhaps within our lifetimes we might actually see real designs of skyhooks and space tethers, these kinds of things. They may be feasible at reasonable cost," Benaroya said.

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