This is an excerpt from EERE Network News, a weekly electronic newsletter.

July 24, 2002

Solar Aircraft Supports HDTV Transmission at 65,000 Feet

It sounds like a technophile's fantasy project: the high-tech worlds of high-definition television (HDTV), video conferencing, wireless internet, solar power, and remote-controlled flight technologies all came together recently in a practical demonstration of what could become the telecommunication industry's newest way to deliver high-bandwidth information to your home. The tests used Pathfinder-Plus—a solar-powered, remote-controlled aircraft—as a high-altitude platform for telecommunications technologies, essentially functioning like a satellite. While circling at 65,600 feet (more than 12 miles) above Kauai, the Pathfinder-Plus successfully re-transmitted an HDTV signal, relayed third-generation cellular audio calls and video conferencing, and provided a high-speed wireless Internet connection. The HDTV transmission used only a watt of power while blanketing an area of land the size of Los Angeles with a high-quality signal for two hours.

The demonstrations were sponsored and funded by a team of Japanese telecommunications researchers from the Japanese Ministry of Communications laboratories as well as two private companies: Japan Stratosphere Communications, Inc. and the U.S.-based SkyTower, Inc., a subsidiary of AeroVironment, Inc. AeroVironment designed and built the Pathfinder-Plus aircraft, which was provided for the tests by the Dryden Flight Research Center, part of the National Aeronautics and Space Administration (NASA). See the Dryden press release and the SkyTower Web site.

Still not enough technology for you? We have more: Dryden is currently working to add a regenerative energy storage system to NASA's ultra-high-flying solar aircraft, the Helios. The system will store energy by converting the craft's excess solar power into hydrogen and oxygen during the day, and then use a fuel cell to "regenerate" the electricity at night. A system light enough to fly on Helios passed muster back in April, consuming 16 kilowatts of electricity for about 5.5 hours and then generating up to 4.6 kilowatts over about 5 hours. NASA plans to attempt a high-altitude overnight flight of the Helios next year, with the goal of eventually developing high-altitude aircraft that can stay aloft for weeks or months. Last year, even without an energy storage system, the solar-powered Helios set a new world altitude record for non-rocket-powered aircraft: 96,863 feet, more than 18 miles high. See the Dryden press release.

NASA is also working on more down-to-earth applications for Kauai: a project is underway to take high-altitude photographs of Kauai's coffee fields from the Pathfinder Plus. The photos will help coffee growers decide when to harvest their fields. The photo technology was tested from a piloted aircraft in 2001 and will be launched on the Pathfinder Plus in September. See the press release from NASA's Ames Research Center.

NASA is committed to developing remote-controlled airplanes, which it calls unmanned aerial vehicles, or UAVs. Officials from Ames, Dryden, Clark University, and the non-profit Girvan Institute signed a memorandum of understanding in late May to establish a "UAV Applications Center" at Ames' NASA Research Park. See the Ames press release.