Ballooning network
helium-filled balloons are being designed by Japanese scientists to create a global communications network. The balloons would cruise at the height of 20,000 metres and revert mobile phone messages back to earth ( New Scientist , Vol 154, No 2085).
The balloons are being developed in a research project at Japan's state-owned Mechanical Engineering Laboratory. Masahiko Onda, in charge of the project, says the balloons would fly far lower than the communications satellites being used for the coming generation of mobile phone systems. This would mean that the mobile phones could be lighter and smaller as they would not need powerful transmitters, he adds.
The durability of the balloons is of great importance for the project to be commercially viable in the near future. The balloons are designed to fly at heights where the air becomes warmer and thinner. As the turbulence at such heights is considerably less than that in the lower atmosphere, where warm air from the heated earth rises through colder air causing turbulence, the life of the craft is longer. "We can keep a balloon aloft for several years, using onboard motors to manoeuvre it,' says Onda.
The researchers have launched three eight-metre-long balloons to test control and recovery techniques. Funds for the project are expected to increase to us $8.3 million a year. This would be enough to launch 20-metre balloons which would fly at higher altitudes.
Several layers of ordinary kitchen clingfilm, which has low gas permeability, would be coated with polythene to make the balloons. They would contain a mixture of 10 per cent helium and 90 per cent air. As the difference in pressure outside and inside the balloons at great heights is enough to make them explode, the balloons would be fitted with a valve to regulate the pressure inside.
The balloons are being designed to run on solar power. Batteries recharged during the day would power the craft at night. Sky Station, a California-based company could be the first to use the airships for commercial applications. The company plans to launch 250 balloons as part of a worldwide mobile phone network.