Inflatable Tower Promises Easy Access to Outer Space
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An inflatable tower nine miles tall and tethered to a mountain top could cut the cost to launch spacecraft, reduce the need for geostationary communications satellites, and improve cell phone signals.
"This structure could be made of commercially available materials," said Brendan Quine, who, along with Raj Seth and George Zhu at York University in Toronto, Canada, wrote an article detailing their tower in the journal Acta Astronautica.
The tower itself would be 15 kilometers (9.3 miles) tall, 230 meters (754 feet) across, and weigh approximately 800,000 tons, or about twice the weight of the world's largest supertanker when fully inflated with a variety of gasses, including helium.
To keep the Kevlar-laminate tower from floating away, and to provide access, three elevator tubes would anchor the tower to the ground. An elevator ride to the top would take about 40 minutes moving at 22 miles per hour.
Tethered to a mountain 3.1 miles high, the tower would initially rise 12.4 miles (20 kilometers). "At 20 kilometers you still have gravity, but the view would be similar to that of an astronaut," with a black, not blue, sky. The ultimate height of an inflatable tower could be 200 kilometers (124 miles). A person, or communications array, could also see 373 miles in any direction from 12.4 miles in the air.
That kind of view would enable the creation of a new wireless data network that could supplement the existing network of geostationary communications satellites some 22,000 miles above the Earth's surface.
A 12.4-mile-high inflatable tower could also lower the cost of launching a satellite by 30 percent, says Quine, reducing the amount of fuel necessary by an entire rocket stage.
Quine says the entire tower could be built using existing materials, and have constructed a 2000:1 scale replica of their tower in a stairwell at York University.
It's an important point; the inflatable tower's main competitor is a space elevator, a platform anchored 80,000 miles high and anchored to Earth with as-yet to be developed material based on carbon nanotubes.
"Towers like this are much more feasible than a space elevator," said J. Storrs Hall, a scientist who proposed a similar tower design several years ago as a potential X Prize goal. The York University scientists have so far created the most detailed plan about how a space tower could be built. "It's a development project, no research necessary. It's the sort of thing we could build before 2020 if we tried."