I’ve been enjoying the ADS-B receiver and having the ability to look up what’s overhead and nearby. I’ve been able to get planes around 50 nm regularly with no issue and sometimes up to 100nm. Today I noticed something interesting - a balloon! Turns out that certain balloons also emit ADS-B signals for location identification. This one happened to be from Project Loon by Alphabet, Inc. I first saw the balloon at around 8am on Saturday morning and took a screen shot on my desktop. The call sign was HBAL111

I continued to observe the balloon throughout the day for several hours. This made me wonder if there was a problem with the balloon. There is currently a dust storm that has come from the Saharan dessert, which seems to be causing low visibility. I’m not sure how it affects wind conditions in the stratosphere and where it could take a balloon.

I researched HBAL111 a bit more and I found out that this particular balloon was launched on February 4, 2020 at 00:01 UTC from Puerto Rico. That makes this balloon 144 day sold and puts at at the top end of its expected lifetime as they are typically brought down after about 150 days.

About Project Loon

Project Loon was developed to bring internet access to remote and rural areas using LTE signals. The balloons fly well above airplanes in the stratosphere. The one I observed was at about 55k feet (16 km) and are reported to be up to 20km up. They fly by using air currents and gather around areas where internet access is needed. By grouping together, the balloons can beam down internet access to people on the ground.

  • Image of Balloon and Custom Launching Station from loon.com

The balloons, or Loon system, has several components that help it deliver internet in the appropriate areas. First off, the balloon is designed to withstand extreme wind and temperatures while still being light enough to be carried by the wind. The whole balloon is about the size of a tennis court and designed to last over 100 days before they come back down to Earth. A team then scoops it up and refurbishes it for another mission. Everything on the balloon itself is highly energy efficient and each one even carries its own solar panel system that allows it to charge a battery for night time operations.

To send internet down to earth, everything starts with a ground station that transmits a signal to balloons. The balloons create a mesh network that transmits down to LTE phones in remote and rural areas. Think of each balloon as an antenna of a wifi mesh network and the ground station is the router. Your device on the ground would roam to the nearest balloon with the best signal and route your internet access to a ground station. The entire system operates autonomously and compensates for balloon motion, weather, and obstructions.

Each balloon travels across the skies by navigating wind patterns. Balloons us predictive wind models and various conditions to make autonomous decisions to move up and down layers of the stratosphere to capture a current that is traveling in the “right” direction. The right direction being the one that the balloon wants travel. All this being said, there are still human operators that are overseeing the entire operation. The goal for balloons is to create a mesh network in the sky that works very much like a series of towers in the city, except much much higher up in the sky.

To get the balloon up in the air is another story and not an easy operation. Imagine trying to inflate a huge balloon on a window morning and then launch it when the windows are just right. It’s a hard task and Loon engineers quickly realized that they needed a custom piece of equipment that would allow them to compensate for this. What this basically amounted to was a big box frame that had curtains on each side to block the wind. The frame can be turned as needed to block the wind. With this custom piece of equipment, they can launch balloons with 3 or 4 people instead of a couple dozen. Win!

For more information, visit Project Loon