Balloon-powered Internet for everyone
Introduction
Project Loon is a network of balloons traveling on the edge of space, designed to provide Internet coverage for people in rural and remote areas, help fill in coverage gaps and bring people back online after disasters. Project Loon, Google's effort to beam broadband Internet access down to remote or rural regions of the globe from a network of stratosphere-roaming balloons. Loon was started inside the company's Google X lab in 2011 and has accompanied other high-flying efforts, such as one to fly solar-powered drones transmitting wireless Internet signals. At the time of Google's early Loon trials in 2013, balloons stayed in the air for about five days, and Google could keep only a few up there at a time. It also took more than a dozen employees to launch each balloon—not a system that could grow efficiently around the world in the way envisioned.
THE TECHNOLOGY
Project Loon balloons float in the stratosphere, twice as high as airplanes and the weather. In the stratosphere, there are many layers of wind, and each layer of wind varies in direction and speed. Loon balloons go where they’re needed by rising or descending into a layer of wind blowing in the desired direction of travel. By partnering with Telecommunications companies to share cellular spectrum we’ve enabled people to connect to the balloon network directly from their phones and other LTE-enabled devices. The signal is then passed across the balloon network and back down to the global Internet on Earth.
HOW LOON FLIES
NAVIGATING WITH THE WIND
Project Loon balloons travel approximately 20 km above the Earth’s surface in the stratosphere. Winds in the stratosphere are stratified, and each layer of wind varies in speed and direction. Project Loon uses software algorithms to determine where its balloons need to go, then moves each one into a layer of wind blowing in the right direction. By moving with the wind, the balloons can be arranged to form one large communications network.
STRATOSPHERE
Situated on the edge of space, between 10 km and 60 km in altitude, the stratosphere presents unique engineering challenges: air pressure is 1% that at sea level, and this thin atmosphere offers less protection from UV radiation and dramatic temperature swings, which can reach as low as -80°C. By carefully designing the balloon envelope to withstand these conditions, Project Loon is able to take advantage of the stratosphere’s steady winds and remain well above weather events, wildlife and airplanes.
HOW LOON IS DESIGNED
ENVELOPE
Each balloon’s electronics are powered by an array of solar panels. The solar array is a flexible plastic laminate supported by a light-weight aluminum frame. It uses high efficiency monocrystalline solar cells. The solar array is mounted at a steep angle to effectively capture sunlight on short winter days at higher latitudes. The array is divided into two sections facing in opposite directions, allowing us to capture energy in any orientation as the balloons spin slowly in the wind. The panels produce approximately 100 Watts of power in full sun, which is enough to keep Loon’s electronics running while also charging a battery for use at night. By moving with the wind and charging in the sun, Project Loon is able to power itself using entirely renewable energy sources.
THE TECHNOLOGY
The inflatable part of the balloon is called a balloon envelope. A well-made balloon envelope is critical for allowing a balloon to last around 100 days in the stratosphere. Loon’s balloon envelopes are made from sheets of polyethylene plastic, and they measure fifteen meters wide by twelve meters tall when fully inflated. When a balloon is ready to be taken out of service, gas is released from the envelope to bring the balloon down to Earth in a controlled descent. In the unlikely event that a balloon drops too quickly, a parachute attached to the top of the envelope is deployed.
SOLAR PANELS
SOLAR PANELS
Each balloon’s electronics are powered by an array of solar panels. The solar array is a flexible plastic laminate supported by a light-weight aluminum frame. It uses high efficiency monocrystalline solar cells. The solar array is mounted at a steep angle to effectively capture sunlight on short winter days at higher latitudes. The array is divided into two sections facing in opposite directions, allowing us to capture energy in any orientation as the balloons spin slowly in the wind. The panels produce approximately 100 Watts of power in full sun, which is enough to keep Loon’s electronics running while also charging a battery for use at night. By moving with the wind and charging in the sun, Project Loon is able to power itself using entirely renewable energy sources.
ELECTRONICS
Each balloon’s electronics are powered by an array of solar panels. The solar array is a flexible plastic laminate supported by a light-weight aluminum frame. It uses high efficiency monocrystalline solar cells. The solar array is mounted at a steep angle to effectively capture sunlight on short winter days at higher latitudes. The array is divided into two sections facing in opposite directions, allowing us to capture energy in any orientation as the balloons spin slowly in the wind. The panels produce approximately 100 Watts of power in full sun, which is enough to keep Loon’s electronics running while also charging a battery for use at night. By moving with the wind and charging in the sun, Project Loon is able to power itself using entirely renewable energy sources.
HOW LOON CONNECTS
Each balloon can provide connectivity to a ground area about 40 km in diameter using a wireless communications technology called LTE. To use LTE, Project Loon partners with telecommunications companies to share cellular spectrum so that people will be able to access the Internet everywhere directly from their phones and other LTE-enabled devices. Balloons relay wireless traffic from cell phones and other devices back to the global Internet using high-speed links.
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