The Incredible Calculations That Keep Google's Project Loon Aloft

By Brent Rose on at

When we last checked in on Project Loon—Google’s moonshot project to blanket the world with internet-packing weather balloons—one had just circumnavigated the globe in a very quick 22 days. I attended a talk at Google I/O and got some more info about some of the challenges the team faces in making this wild-ass project happen.

First off, if you need a refresher on what Project Loon is, here ya go.

The Incredible Calculations That Keep Google's Project Loon Aloft

Now then. We learned earlier this week that the team names their balloons after birds. For example, one we heard about today was called Ibis. This gives them an easier way to remember and reference one, should it be keep coming up.

The Incredible Calculations That Keep Google's Project Loon Aloft

These balloons float at altitudes up to 25 kilometres (15.5 miles) and travel as fast as 324 km/h (201 miles per hour). That’s about as fast as a peregrine falcon can dive, which is nuts. As you might imagine, keeping track of a fleet of these things is rather challenging. So, just like NASA, Project Loon built a mission control.

The Incredible Calculations That Keep Google's Project Loon Aloft

Mission control conjures images of a bunch of people crowded into a semi-circular room staring at monitors and such. Loon’s mission control system is more of an online thing. Not only does it work on standard computers, but the flight engineers who monitor the balloons 24/7 can get all the data they need on smartphones and tablets, too.

The Incredible Calculations That Keep Google's Project Loon Aloft

Just like with planes, if a mission control system detects that a balloon is about to enter another airspace, it will needs to send a message to the air traffic control in the new area so they can coordinate. With the system Google has designed, though, this detecting and alerting happens automatically.

The Incredible Calculations That Keep Google's Project Loon Aloft

The team has an advanced system to monitor the balloon’s health. Too much pressure inside and it bursts. Too little it could lose buoyancy. So they need to be able to monitor the amount and pressure inside the balloon. This is largely dependent on the ambient temperature, which is actually very hard to measure when it’s that high. Radiation from the sun can really screw up the data. So they have had to outfit the balloons with sensors in different locations so they can get a real look at the temperature regardless of the common variables they encounter. This data is crunched server-side which gives the flight engineers information they can act on.

The Incredible Calculations That Keep Google's Project Loon Aloft

They also need to keep track of the state of their batteries. The balloons have solar panels that charge during the day, but of course they need to run at night, too. There are a ton of different variables that affect battery life. Differences in temperature and load level (say if they’re running the onboard heaters, etc.) can dramatically impact the battery’s health. Solar is tricky, too. Unlike the solar panels on your house, during peak hours solar hours the balloon actually casts a shadow on the solar panels which causes a dip in how much energy can be generated. This makes a Batman insignia-shaped wave when you look at it on a chart.

The Incredible Calculations That Keep Google's Project Loon Aloft

Then, of course, there’s all the navigational data, which is almost certainly the hardest to work with. Since Loon is dependent on the wind to travel, the team gets publicly available weather data from NOAA. They then make three-dimensional wind maps that can predict the direction of the wind at different altitudes. You can see this cube-shaped model above. They refresh their data from NOAA data every 6 hours, but they have to make 16-day models out of that. That is just a tremendous amount of data. Luckily Google isn’t exactly hurting for server power.

The Incredible Calculations That Keep Google's Project Loon Aloft

With the data gathered from Loon, the team created a program called the Crazy Simple Planner which helps them predict a trajectory to help point the balloon to where they want it to go. It’s very visual and very easy to interpret the data through that lens. Or it’s easier, anyway. Nothing about this stuff looks remotely easy.

The Incredible Calculations That Keep Google's Project Loon Aloft

They also understand that shit happens. As anyone who has planned a camping trip knows, weather doesn’t always line up with the predictions. There’s wind-noise and other complications. So they have other programs that run contingency calculations to help them estimate where balloons will end up. They used advanced simulations to help them do this, like the one you see above. You can try a lot of different things in sim pretty easily. Moving thousands of balloons around the globe, not so much.

The Incredible Calculations That Keep Google's Project Loon Aloft

All this adds up to a program that’s knocking off some pretty major achievements. Not only did a Loon balloon manage that trip around the globe 11 days faster than was predicted, but another balloon managed to land within 500 metres (547 yards) of its targeted landing spot after an extremely long 12,000+ mile flight. A balloon did that with no propulsion—just rising and falling to ride the different wind currents. Pretty amazing.

The Incredible Calculations That Keep Google's Project Loon Aloft

The Project Loon team acknowledged that they still have a long way to go before they’re able to make uninterrupted internet access available to every human on the planet, but it’s incredible how far they’ve come in just a couple years. Hopefully they’ll continue ramping things up, and the hilarious UFO scares will continue in perpetuity. [Project Loon]