Google wants to bring wireless internet service to the whole world through its airborne Loon network. The pilot project got off the ground on June 15th, launching from Christchurch New Zealand.
A Loon is a helium-filled mylar balloon floating about 20 km (12 mi) above the Earth’s surface, carrying an internet router and associated gear. Each unit can provide internet access to a 40 square km area. Google plans a network of Loons that communicate with the ground and with other Loons. Hundreds of Loons combined could provide wireless internet access worldwide. Communication uses the 2.4 GHz and 5.8 GHz bands which are publically available without a special license. Internet speeds are roughly equivalent to 3G speeds. Although cell service can already reach many remote areas, Google thinks the Loon network could provide internet access to areas where cellular companies haven’t penetrated, as well as locations that have been struck by natural disasters, knocking out cell service. Since it uses low-cost balloons instead of satellites, the total cost will be much lower than the $7 billion that Motorola invested in its Iridium phone network.
Instead of being tethered to the ground, the Loons move on air currents. As one floats out of range, another should float in range. Each Loon includes a solar powered fan to pump air in and out of the balloon, allowing the Loon to change altitudes in order to maintain its position relative to the other balloons in the network. And if the Loon should malfunction and fall from the sky, a built-in parachute will deploy. The Loon’s case has a label saying “Harmless Science Experiment” along with contact information and a “Reward if Returned” notice.
Here is Google’s description of the project:
The Loon sports four lightweight photovoltaic panels (see photo below), which provide enough electricity to power the on-board computers, navigation system, and communications hardware. During peak sun, the PV panels generate 100 watts, much more power than necessary to operate its electronics. Some of the excess energy is used to generate heat, which keeps the electronics running at optimal temperatures, since it’s very cold at 20 km. The remaining energy charges the Loon’s batteries, roughly the equivalent of ten laptop batteries.
To reduce energy consumption, the Loon uses very low-power electronics. Its computer runs on about one-tenth of the power of a standard laptop. The Loon has three identical onboard computers, providing triple-modular redundancy in case one computer fails.
Solar panels work a lot better at higher altitudes. At 20 km, there is much less atmosphere to absorb the sun’s rays. In fact, the air mass at 20 km is only 5% of the air mass at sea level. Above the Earth’s atmosphere, the solar power available is 1366 w/m2. At sea level it’s 1000 w/m2. If a solar panel is 1 m2 in area with 10% efficiency, it will generate 100 watts at sea level and 136.6 watts if it’s positioned above the atmosphere. At an altitude of 20 km that panel will generate approximately 130 watts.
Considering the wireless nature and the altitudes involved, solar power is the obvious choice. But this innovation could spark a number of other airborne technologies, all powered by photovoltaics. Widespread use will drive solar panel prices down for consumers, making the cost of solar power even more affordable. In addition to bringing the internet to the world, Google is also helping to bring solar power to the world. There’s nothing “loony” about that!