How Loon's Balloons Find Their Way to Deliver the Internet

Since Loon spun out of X last summer, the company’s balloons have logged 1 million hours of flight time and found some novel ways to navigate the stratosphere.

Loon

Watching a balloon zag instead of zig, Sal Candido often feels like Dr. John Watson observing Sherlock Holmes. As CTO of Loon, the Alphabet company that last summer spun out of X (née Google X), Candido is in charge of the balloons that bop through the stratosphere, beaming the internet to people below. Flying about 60,000 feet above sparsely populated or mountainous areas, where traditional telecoms don’t bother building networks of cell towers, a single balloon can cover 2,000 square miles with the joy of getting online .

Alex Davies covers autonomous vehicles and other transportation machines for WIRED.

To provide coverage over an area, Loon runs packs of five to 10 balloons. Together, they can provide an aerial mesh network (more users require more balloons) with backup balloons waiting nearby, ready to hop up. Loon is testing over western Peru, offering service to an undisclosed number of people. The balloons can only spend so long aloft, and Loon generally brings them down after 150 days. Technical difficulties like dying batteries shorten the lives of others. But more often than not, it’s the wind that’s the culprit, simply blowing a balloon out of its service area.

Staying put is no simple task for a gas bag that’s the size of a tennis court and has no way to resist the wind. Loon’s balloons navigate by moving up and down, looking for the air currents that will take them where they need to be. To do that, they are not “hand-flown,” or manually directed by human beings. Instead, they follow complex algorithms that Candido’s team has spent years honing, a computer-borne approach to the world that produces flight paths that seem anything but elementary.

The problem with this sort of navigation is that wind currents are shifty things. Riding them through the sky is like using a road network where streets change their directions, number of lanes, and speed limits, or even disappear altogether at unpredictable times. What's more, the global models of wind speeds and directions built by the National Oceanic and Atmospheric Administration and its European equivalent, using disposable weather balloons carrying radiosondes, leave much room for error. So if you were watching a balloon fly west when its target is to the east, you would probably think that it was broken, or that the algorithm directing it was faulty. But over the past six years, during which Loon balloons have logged a collective 1 million hours of flight time, Candido has learned not to judge so quickly.

After launching from Puerto Rico, one balloon made its way to Peru by periodically changing its direction to negotiate headwinds—what a human sailor would recognize as tacking.

Loon

By churning through years of measurements and the latest weather reports, including data from the 50 or so balloons Loon has aloft at any given moment, his team’s model has developed its own paths. So rather than assuming an itinerant balloon is broken or malfunctioning, Candido watches and waits. Much of the time, hours or days later, he finds that the balloon has found an unexpected but efficient path through the sky. The floaters tack against headwinds, like skilled sailors. They fly figure eights over their area, where a human pilot would naturally think to go in circles. When they’re knocked off course, they “strategically loiter,” in Candido’s phrase—appearing to loaf while waiting for the wind that will whoosh them home. Like flying Sherlocks, they ingest more data than a clever human and produce results that only seem obvious in retrospect.

To capture the complexity of the task, Loon’s engineers use what they call, unimaginatively, the Cartographer Map. It denotes distance as a function of time, rather than miles: Dark blue shading means it’ll take minutes to get to a given destination, dark red means you’ll be flying for days. Shown below as a weeklong time-lapse, the result is an undulating blob that calls to mind a 1990s-era Windows screensaver, but distills the worldview of an internet balloon: It’s not the distance that matters, but the time it takes to get there.

To capture the way their balloons see the world, Loon’s engineers use a dynamic map that changes along with wind patterns. Dark blue means you’ll move quickly, red more slowly.

The learnings that come with that philosophy are key to Loon’s long-term chance at success, because Candido and his team can’t spend their time directing a global fleet of balloons. “Now we do zero hand-flying,” he says. Meanwhile, his colleagues are working to automate other aspects of their business, like alerting their balloons to FAA notices of temporary flight restrictions. (Communication with authorities around the world—which includes faxing documents to the FAA and exchanging WhatsApp messages with foreign air forces—will likely retain its human quality.)

In the year since it spun out from X and became its own company, Loon has notched a few milestones, signaling improvements in hardware and software. Its balloons have now covered covered about 25 million miles. One balloon (exempted from the 150-day limit) recently set a stratospheric flight record for any aircraft, logging 223 days airborne. Another mastered the wind to the point where it spent nearly five months over a single location.

Note the flight paths of two balloons over Puerto Rico. The white balloon went far to the southwest to hook up with a wind that would bring it back, while its orange fellow “strategically loitered” nearby and found its way home faster.

Turning that know-how into revenue is coming more slowly. After Hurricane Maria pummeled Puerto Rico—where Loon launches its balloons—in September 2017, the company used its high-fliers to provide internet connectivity to more than 100,000 people. But four years after Loon announced it would deliver internet service in Indonesia, it hasn’t closed the deal. “These engagements are ongoing and we have recently made some encouraging progress,” says spokesperson Scott Coriell.

Loon recently received approval from Kenyan authorities to test in that country’s airspace, a year after announcing a deal to fly there . It hopes to start commercial service by the end of the year. In May, Loon balloons helped provide service over Peru (where it does much of its testing) after a magnitude 8.0 earthquake. The company is “in conversations” to start a regular, commercial service there, Coriell adds.

Candido and his engineers, for their part, remain focused on helping their balloons find their own way. They haven’t got their heads in the clouds—they’re flying way above them.

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