Looney Balloons

Tuesday, December 16th, 2014

Google’s far-fetched Project Loon seems to be working:

[A]s you read this, some 75 Google balloons are airborne, hovering somewhere over the far reaches of the Southern Hemisphere, automatically adjusting their altitudes according to complex algorithms in order to catch wind currents that will keep them on course. By next year, Google believes it will be able to create a continuous, 50-mile-wide ring of Internet service around the globe. And by 2016, Project Loon director Mike Cassidy anticipates the first customers in rural South America, Southern Africa, or Oceania will be able to sign up for cellular LTE service provided by Google balloons. (Google is starting in the far Southern Hemisphere, which is relatively sparsely populated, before expanding elsewhere.)

It took a while to get going though:

On the first try, the balloon burst not long after liftoff, the nylon fabric overmatched by the 100,000 pounds of pressure within. The same happened on the second try, and the third—and the next 50 after that. The team kept tweaking the fabric and reinforcing it with more Kevlar-like ropes, but the balloons kept bursting until they got the length of the ropes exactly right. (They had to be shorter than the fabric to relieve the pressure, but not too much shorter.)

“We knew it was hard to make a super-pressure balloon,” Cassidy recalls. “We didn’t think it would take us 61 attempts until we succeeded.”

Even then, the success was short-lived. Instead of bursting, the balloon slowly leaked helium, bringing it down after just a day or two in flight. “Even a millimeter-sized hole will bring a balloon like this down in a couple days,” Cassidy says. “And that’s what happened to the next 40 or 50 balloons we made.”

Google’s engineers spent weeks trying to isolate the problem. They took balloons out of their boxes and inflated them in a cavernous hangar at Moffett Field in Mountain View, shined polarized light through them, and even sniffed for helium leaks using a mass spectrometer. Each balloon that went down was subjected to a “failure analysis” that included poring over meticulous records of who had assembled it, where, and using what equipment, and how it had been transported.

Eventually they pinned the leaks on two sets of problems. One was that the balloons had to be folded several times over to be transported, and some developed tiny tears at the corners where they’d been folded repeatedly. Google set to work finding ways to fold and roll the balloons that would distribute the stress more evenly across the fabric.

The second problem was that some balloons were ripping slightly when workers stepped on the fabric with their socks. The solution to that problem? “Fluffier socks,” says Cassidy. “Seriously, that made a difference. Softer socks meant fewer leaks.”

As the team cut down on the leaks, the balloons started lasting longer: four days, then six, then several weeks at a time. As of November, Cassidy says, two out of every three balloons remain in the sky for at least 100 days.

But keeping the balloons airborne is only the first of the monumental problems that the project presented. Keeping them on course may be even harder.

Why do this again?

Providing Internet via a fleet of algorithmically directed balloons might sound prohibitively expensive, but Cassidy says it’s actually an order of magnitude cheaper than setting up and maintaining cell towers, making it more economically viable in remote regions.

Comments

  1. Toddy Cat says:

    Where is Frank Luke when you need him?

    http://acepilots.com/wwi/us_luke.html

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