Loon
Beaming the internet with stratospheric balloons
Loon was a radical approach to bringing internet access to rural, remote, and underserved areas using a system of balloons, carried by winds in the stratosphere. After nine years of groundbreaking technical achievements, Loon wound down, but its technological legacy lives on. The team shared its learnings in The Loon Collection — a shared archive of insights for future stratospheric explorers — and some of its technology can be found in Taara, which uses light beams to deliver abundant, affordable connectivity.
Loon balloons traveled along the edge of space to deliver internet to the ground below.
Bringing Billions of People Online
The internet has transformed the way the world communicates, learns, governs, and exchanges ideas, but billions of people across the globe lack reliable, affordable access. Loon was a radical approach to expanding internet connectivity. Instead of trying to extend the internet with traditional ground-based infrastructure like fiber optic cables or cell phone towers, Loon took to the sky. Floating at the edge of space, Loon's balloons created a network capable of expanding internet connectivity to rural areas, filling coverage gaps and improving network resilience in the event of disaster.
Using Loon balloons to connect a classroom in Brazil, 2014
Connecting the Unconnected
The Loon team began with a question: Could a fleet of stratospheric internet-beaming balloons be the radical idea that might finally bring abundant, affordable internet access, not just to the next billion, but to the last billion? To the last unconnected communities and those least able to pay?
To see if the idea had promise, the Loon team started by flying (and chasing) early prototypes through California's Central Valley. In 2013, the team found some friendly New Zealanders, who were the first in the world to connect to the internet via a stratospheric balloon. These early tests demonstrated Loon’s promise, and after more development, the team beamed the first LTE connection from the stratosphere to a school in Brazil, showing that it was possible for balloons to connect directly to people’s phones.
Over the years, Loon knocked over one technical hurdle after another, achieving feats previously considered impossible — like using lasers to transmit data (and beam a copy of the film "Real Genius" between balloons) or creating a mesh network in the sky.
In 2017, when flooding in Peru and a major hurricane in Puerto Rico knocked out critical ground infrastructure, the Loon team navigated balloons to the disaster regions and provided emergency connectivity to hundreds of thousands of people. In 2018, Loon became an independent business within Alphabet and in 2020 the team co-founded the HAPS Alliance, which aims to accelerate innovation and connectivity efforts in the stratosphere. In 2020, Loon and its partners launched the world’s first internet-via-balloon service to people in unserved regions of Kenya.
Building a Balloon That Lasts
The stratosphere is unforgiving — winds can reach 100 km/hour, and temperatures can drop to -90 degrees Celsius. The Loon team needed to design a balloon that could withstand the extremes for hundreds of days — all while delivering constant connectivity. The team spent years refining its designs, and eventually set a record with a balloon that flew more than 300 days before coming down to Earth.
While prototyping and refining balloons, the team was also focused on another big challenge: how to get them up in the air reliably, safely and quickly? To achieve this, the team designed and custom-built autolaunchers (affectionately named “Chicken Little” and “Big Bird”). These large cranes filled and launched a balloon into the stratosphere every 30 minutes, sending them high above airplanes, birds and the weather.
The Loon team's custom-built autolauncher
Sailing the Stratosphere
Winds in the stratosphere are layered, with prevailing winds at one altitude varying in speed and direction from those at slightly different altitudes. One of the Loon team’s original insights was to take advantage of this variability and “sail” the winds, rather than fly against them. By designing a balloon capable of ascending or descending to catch a favorable wind, the Loon team could sail through the stratosphere without propulsion, breezing to locations around the world.
To identify helpful wind patterns, Loon used advanced predictive models to create interactive maps of the skies. These maps allowed the team to determine the wind speed and direction at specific altitudes, times, and locations. The team then developed smart algorithms to help determine the most effective flight paths through the varying wind layers. Using these algorithms, the balloons could accurately sail the winds over thousands of kilometers to reach a desired location and remain clustered around those destinations to deliver consistent connectivity below.
Predictive models help move each balloon into a layer of wind blowing in the right direction. Advanced algorithms let small groups of balloons cluster over specific regions.
The Loon Balloon
Each tennis-court-sized, polyethylene balloon was built to survive for hundreds of days in the stratosphere’s harsh conditions
While in the stratosphere, balloons encountered 150°C temperature swings, with temperatures reaching as low as -90°C.
Changing the airflow into a smaller inner balloon called the ballonet would cause a balloon to change altitude and — by catching a different wind current — its direction as well.
Solar panels powered the communications equipment during the day and charged onboard batteries for nighttime operation.
The avionics system contained the technical brains that controlled and commanded the balloon.
An onboard parachute allowed for a controlled descent and safe landing.
Transceivers and antennas relayed a high-speed internet signal across the balloon network and to people below.
Loon Today
Despite Loon’s extraordinary technical progress, the path to commercial viability proved much longer and riskier than hoped. So in 2021, Loon’s journey came to an end. To help further stratospheric research and innovation, the team published The Loon Collection — a catalog of the project’s technical, operational, and scientific insights. Just as Loon built upon the pioneering work of others, we hope that these resources will support future exploration in the skies and keep stratospheric research and innovation aloft.
