Expanding internet connectivity with stratospheric balloons

Billions of people across the globe still don’t have reliable, affordable access to the internet

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 optics cables or cell phone towers, Loon took to the sky with a network of balloons. Loon's balloons traveled along the edge of space to expand internet connectivity to rural areas, fill coverage gaps, and improve network resilience in the event of disaster.

Loon spent nine years developing technologies to deliver connectivity from the stratosphere

Loon balloons traveled along the edge of space to deliver internet to the ground below

Connecting the unconnected

The Loon team began with a question: Could a network 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 explore this idea the Loon team started out flying (and chasing) early prototypes through California's central valley to see if the idea had promise. 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, doing things previously thought impossible — like using lasers to beam connectivity (and a copy of the film Real Genius) between balloons in the stratosphere, 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 launched the world’s first internet-via-balloon service with partners to people in unserved regions of Kenya.


Building a balloon that lasts

The Loon team had a lofty goal: designing a balloon that could last for hundreds of days in the harsh conditions of the stratosphere, where winds can reach 100 km/hour and temperatures can drop to -90 degrees Celsius — all while delivering constant connectivity. The team spent years refining their designs, and eventually set a record with a balloon that flew more than 300 days before it came down to Earth.

Launching the balloons

While prototyping and refining their balloons, the team were 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 that the team affectionately called Chicken Little and Big Bird. These large cranes were capable of filling and launching a balloon every 30 minutes into the stratosphere — high above airplanes, birds, and the weather.

The Loon team's custom-built autolauncher

Sailing the stratosphere

Wind patterns 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 original insights from the Loon team was to take advantage of this variability to “sail” the winds, rather than to 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 with no propulsion, reaching 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. With the aid of these algorithms, the balloons could accurately sail the winds over thousands of kilometers to reach a desired location and remain clustered around those destinations in order to deliver consistent connectivity below.

The Loon balloon: Delivering connectivity from the stratosphere

While in the stratosphere, balloons encountered 150°C temperature swings, with temperatures reaching as low as -90°C
Each tennis-court-sized, polyethylene balloon was built to survive for hundreds of days in the stratosphere’s harsh conditions
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

Expanding internet coverage: The Loon communication payload and BUS system

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

Sharing Loon’s lessons with the world

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 Loon’s technical, operational, and scientific insights. The collection includes flight data from all 2,100 of Loon’s flights, including sensor data and electrical measurements, for scientific and climate research.

Some of Loon’s technology, like the high-bandwidth optical communication links first used to beam a connection between balloons bopping in the stratosphere, lives on in Project Taara. To support ongoing innovation in the High Altitude Platform Station (HAPS) communications industry, Loon transferred a number of stratospheric ballooning and networking patents to partners working in similar fields. Loon also made a non-assertion pledge for the free use of more than 200 other patents related to launching, navigating, fleet management and more.

Just as Loon’s technology is built on the pioneering work of others, we hope that these resources will support future exploration in the skies and keep stratospheric research and innovation aloft.