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[Chicago Astronomer Joe]

Express lift to the stars

A radically different way to reach outer space -- the space elevator -- may finally be getting off the ground floor thanks to recent huge advances in technology.

Traveling thousands of miles into the cosmos up a length of super-strong material, it is believed that the space elevator could revolutionize space exploration by providing an affordable means of transporting satellites, space station supplies, and one day even tourists into space.

The basic premise involves an elevator that would travel from its base station up a cable tethered at the other end to a counterweight in geo-stationary orbit. Satellites, supplies or astronauts would be loaded onto the elevator climber at the offshore platform anchored on the equator, where risks of storms, lightning and hurricanes are minimal.

The main stumbling block in the past has been finding a material strong and light enough to reach up to 62,000 miles into space.

The concept of the space elevator was first mooted by Russian engineer Yuri Artsutanov in the 1960s, and until recently has remained more familiar to fans of science fiction, such as Arthur C. Clarke's1979 novel, "The Fountains of Paradise."

Previous ideas, such as lassoing one end of the elevator cable to an asteroid in geo-stationary orbit, haven't helped the concept to be accepted as a serious project.

A paper-thin ribbon of approximately one meter in width composed of multiple strings of nanotubes - essentially sheets of graphite, a lattice of carbon - seamlessly rolled into long tubes that are only nanometers in diameter.

To the naked eye it would appear semi-transparent and no thicker than that width of a pencil, yet would be incredibly strong and light. Recently produced carbon nanotube fibers have been found to be over 20 times stronger than steel wire.

A deployment satellite would send up the initial string of ribbon, which would be added to by climbers carrying further lengths of carbon nanotubes until it was the required width. The ribbon would he held taut by the motion of the weight -- much like the way in which a weight on the end of a string stays taut when spun.

Estimates that sending material into space on the elevator would cost approximately $100 per kilogram, compared to the shuttle costing between $10,000 and $40,000 per kilogram.

Source and full story: edition.cnn.com/2006/TECH/space/09/18/space.elevator/

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This simple mind can't see how the Space Elevator would safely work. Any deviation from the perpendicular would elongate/stretch/alter the cable and could cascade into a domino failure. Would it then drag the anchor satellite along with the rotation of the Earth - unguided? And having tethers reaching up thru the atmosphere would pose an air traffic hazard as well.

I'm just not sure on this Space elevator concept...

[Chicago Astronomer Joe]

Elevator Brings Earthbound Surprizes

Even on the ground, space elevators may have uses

Balloon-borne platforms developed as precursors to space elevators could be used as high-altitude relay stations for wireless communications, a 60-day field test suggests.

But that test lasted for only six hours. Now, LiftPort has finished a 60-day test with a 100-metre-long tether held aloft by four helium balloons. The test was designed to see what kinds of problems would crop up if such a platform were used to transmit Wi-Fi signals. The lofty platforms would be especially useful for providing Wi-Fi coverage to rural areas, says company president Michael Laine.

Swallows and bats

Overall, he says, the test went well, but there were several unexpected encounters with wildlife. More than a dozen insect egg colonies had been laid on the tether, and in the first few days of the test, curious bats flew around the balloons, apparently attracted by the sound made by the tether's vibrations. Late in the test, swallows were also seen swooping down on the balloons, possibly to sip the morning dew on their surfaces.

The team learned that if the tether is pulled hard by wind, it starts to buckle and deform slightly, creating crinkles. The robot climber hit these crinkles and could not proceed because they made the tether too thick for it to handle.

"We broke our robot by doing this," Laine says. "It's the kind of failure we never would have learned had we only been doing 6-hour tests." Future designs will have to incorporate sensors to tell the robot when it is about to encounter varying thicknesses.

Source: www.newscientistspace.com/article/dn10161-even-on-the-ground-space-elevators-may-have-uses.html

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I had not thought about the crinkles in the tether nor the animal and insect life interacting with the elevator.

Quite interesting and yet another reason I don't think it will work.