Michael Molen and Sanswire’s Eye in the Sky
8 July 2004 — This month, a 3000-meter-high antenna will rise over Atlanta, but area residents might not notice. The antenna won’t be a metal rod at the end of a hulking tower, but a solar-powered, helium-and-nitrogen�filled airship that will receive signals from nearby ground stations and rebroadcast them over the Atlanta metropolitan area.
The test transmission of voice, data, and video in many standard forms will be part of a demonstration planned by a local company, Sanswire Networks LLC, to show that high-altitude platforms — or HAPs as they are known in the telecommunications world — can work as mid-air base stations for wireless communications.
Photo Source:sanswire Networks LLC
Sanswire’s Stratellite:
which closely resembles a whale out of water, has been flattened in order to make more of its surface area upward facing. This has significantly increased the area covered by solar arrays [shown as brown and green grid] that provide power for propulsion and for running the onboard communications payload.
The Atlanta demo is a proof-of-concept designed to satisfy certain technical and regulatory concerns. It’s a warm-up for what will be an even more important test of an actual commercial system. In the full-scale version, a larger airship, already designed, will float into the stratosphere and hold its position at 20 000 meters. At that altitude, a single ship’s coverage area will be about 337 000 square kilometers , an area roughly the size of Germany. Thirteen airships working together could reach all points in the continental United States.
The Sanswire projects are representative of work being done on high-altitude communications platforms by companies and consortia around the globe. The reason using balloons or solar-powered drones for communications seems so attractive to so many experts is that these platforms combine the best features of satellite and terrestrial systems. They should be considerably cheaper than satellites to launch, retrievable so that updated equipment can be installed, and remotely controlled for placement where they would be most effective. And, in contrast to ground-based antennas, the high-altitude platforms will have a direct line-of-sight to all receivers, covering a much greater area than an antenna tower could hope to reach.
Sanswire is confident that the technology to be used for this month’s test also will work fine in the bigger commercial system. Perhaps the most challenging hurdle was the design of the balloon itself, which had to be changed so that one of two Kevlar envelopes containing the airship’s lighter-than-air gases would accommodate enough solar cells on its surface to provide the requisite power. “We’ve solved the energy problem,” Sanswire CEO Michael K. Molen boasted in a conversation with IEEE Spectrum.” In fact, he said, the solar panels on their “stratellites” — so-called because they act like satellites but perch in the stratosphere — capture enough energy to run for 10 days with no light.
Molen acknowledged that an earlier design didn’t draw enough energy from the sun’s rays during the day to power the propellers that maintain the airship’s position and run the onboard electronics after dark. But its latest design, which is reminiscent of a whale, yielded much more skyward-facing surface, 5400 square meters, and so, more energy [see illustration].
Based on its technical progress, Sanswire, which is a subsidiary of GlobeTel Communications Corp., Pembroke Pine, Fla., has been busy working out agreements with communications companies in Australia, Europe, South America, the Caribbean, and Russia. Molen told Spectrum that the Australian government is serious about its push to provide broadband access to its 20 million residents. The fact that Australians are spread over an area roughly the size of the United States makes landlines and even terrestrial wireless base stations impractical, and the government is highly motivated to take a chance on something unorthodox, he says.
By early September, Sanswire’s Australian subsidiary will start building the full-size airship designed to remain at 20 000 meters for 18 months at a time. It is intended to come down only when technological advances make the onboard equipment outmoded. Molen told Spectrum that Sanswire expects to launch the stratellite by the third quarter of 2005.
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