A new frontier for wireless communications has emerged amid the Earth's second layer of atmosphere -- the stratosphere -- where airplanes soar and convection-propelled turbulence can be avoided.
After airships' reputation went up in flames with the Hindenburg in 1937, the fate of the bulbous aircraft seemed destined to remain as floating billboards above football stadiums. But airships have recently experienced a drastic turnaround as many organizations are looking at airships and balloons as the next platform for wireless communication delivery.
A handful of companies are racing to create airships to float 65,000 feet in the Earth's stratosphere for months at a time, and transmit wireless communications over huge expanses of territory. Airships are seen as a likely alternative to satellite transmissions and cell towers, which are hampered by line-of-sight limitations and shorter transmitting ranges.
Return of the Airship
Florida-based Sanswire is developing "Stratellite," a rigid, solar-powered airship that is anticipated to soar 60,000 to 70,000 feet in the stratosphere.
Sanswire hopes that once the Stratellite performs as expected, it will consistently deliver Wi-Fi connections at 5.8 GHz and licensed spectrum ranges to Internet service providers with a line of sight to a 300,000 square mile area -- approximately the size of Texas. This will enable one airship to provide advanced services to areas of up to 126,000 square miles. The Stratellite is also expected to be offered at a lower cost than current technologies like cellular, 3G, paging, fixed wireless and high-definition TV broadcasts.
"We want to take the cell tower, and instead of having it be 30, 40 or 100 feet above the ground, take it up to 65,000 feet, and that gives you a huge increase in line-of-sight capability," said Doug Murch, president of Sanswire.
The Stratellite is similar in shape to a blimp. It is 127 feet long, 27,800 cubic feet in volume and has a polyethylene outer shell covered in photovoltaic units. Murch's hope is that the unmanned airship will be propelled by gas technology beyond the jet stream. Once it reaches the stratosphere, it will be held in place by five helium bags in the vessel's interior and propelled by solar-powered electrical engines.
The company's operation center on the ground will control the airship remotely.
The stratosphere provides an attractive location for communications because its placement puts airships above tumultuous air currents and disruptive turbulence. An airship in the stratosphere can be made to hover or move in a predictable pattern, so it can send and receive transmissions with great accuracy.
During the dot-com boom, several companies toyed with the idea of delivering Internet and phone service through airships, but many of these ideas foundered when the Internet bubble popped and broadband Internet proliferated through phone and cable lines.
Yet now Boeing, Space Data, Sanswire, Techsphere and 21st Century Airships are researching the possibility of using airships and balloons as communications platforms. The U.S. military is also exploring the possibility of using airships for airborne reconnaissance and homeland security purposes.
Even so, airships have yet to deliver on these lofty promises. No company has created a large airship that can hover in the stratosphere -- where clouds rarely form and temperatures remain around freezing -- for months at a time. Yet advances in composite structures, photovoltaics, man-made fabrics, electric motors and energy storage technologies have put the 65,000-feet goal within reach, Murch said.
"It's important for everyone to know that this process to getting to near space is a pioneering work," Murch said. "Nobody has ever done it; no one has ever gone up and actually used an airship in near space for a telecommunications platform."
The core obstacle in maintaining an airship at stratospheric levels has been energy regeneration, since an airship needs to stay in near space for long periods of time to remain commercially viable. No airship has stayed afloat at high altitudes for more than 24 hours because energy resources are quickly expended, Murch said.
However, Sanswire is using existing technologies, such as solar power regeneration, to power the Stratellite. The company also expects research being conducted on hydrogen fuel cells to yield another alternative in the near future.
Helium retention is also a problem for the Stratellite, and Sanswire is looking for new materials to help prevent the small particles from escaping.
Arizona-based Space Data has figured out a way around the technological roadblock that large airships have encountered. The company has developed "SkySat" balloons: six-foot-wide latex rubber balloons filled with helium or hydrogen and equipped with communications gear. By launching balloons daily, Space Data does not have to maintain and launch a large aircraft. The reusable balloons are controlled remotely and drop safely to the ground after a few days.
Over the past two years, Space Data has launched more than 10,000 balloons over Texas, Oklahoma and parts of Arkansas and Louisiana, to help the oil industry monitor oil and gas production, and keep track of equipment.
In August 2006, Space Data was awarded a $49 million contract from the U.S. Air Force to supply its high-altitude balloons with communications. The move will replace high-cost satellites, and the balloons are expected to be used to extend the communications range of soldiers in Iraq and Afghanistan.
Former North Dakota Gov. Ed Schafer is working with Space Data to use its balloons to provide wireless coverage to remote parts of the state. The plan is expected to be effective in 2007 and is precisely the market Space Data is pursuing -- jurisdictions that want to bring wireless communication services to areas with little or no reception.
"The goal of our company is to have an umbrella overlay system over the entire nation, with a network capacity and a user base of 200 million cell phone users," said Jerry Knoblach, chairman and CEO of Space Data. "We want to be a roaming partner to big carriers."
Knoblach thinks airships will make headway in the future as technology develops, but for now, they only exist in PowerPoint presentations.
Yet Murch is confident the Stratellite will be the next communications platform of choice in the coming years. In the months ahead, Sanswire will conduct further testing of the Stratellite at Edwards Air Force base, about 30 miles north of Palmdale, Calif., with the goal for the Stratellite to float at 25,000 feet for 24 hours. The company's immediate goal is to have the Stratellite stay afloat for seven days, then continually extend the number of days. Murch hopes that in the next two to three years, a successful Stratellite prototype will be unveiled to the world.
"It's very doable. We're sure it's going to be happening," Murch said, "and in some way, we are going to be a part of it."