[carlosrr]

Looks like gravity helped:

"At over 100,000ft the balloon lost its inflation and the equipment was returned to the earth.

"We travelled 10km to find the sensors and photographic card, which was still emitting its signal, even though it had been exposed to the most extreme conditions."

[dkokelley]

I'm surprised that it didn't travel farther than 10km. There must have been 0 wind that day.

[kirse]

Seriously. I ran a little experiment back one high school summer when I had a helium tank laying around and was bored/curious to know how far your typical lost-to-the-sky "Walmart" helium balloon would travel.

I launched about 50 balloons of varying inflation levels and groups (i.e. 1,2, and 3 balloons) and attached ribbons to them and tied laminated index cards with a numeric-ID and my email address.

I ended up getting a few responses and I believe one of the single balloons traveled over 76 miles before setting down in someone's backyard. The average was something like 50 miles, and that was on a warm night with <5mph wind.

[Gibbon]

I found a similar balloon in a tree once. It had been launched at a birthday party for an 85 year old woman and travelled about 250 kms.

We launched thousands of baloons with index cards, once a year, in primary school but I never received a reply from any of mine.

It's definitely fun though!

[dkokelley]

So then how could a balloon that traveled 100,000ft vertically land within 10km? Maybe the larger mass keeps the wind from pushing it so far.

[ars]

Avoid the jet stream and trade winds. Specifically launch in the "Horse latitudes", and wait for a calm day. The very southern tip of spain is located in the horse latitudes.

[marvin]

The helium balloons probably didn't fall back down to earth as soon as the balloon in the story. But I still think that only 10 km seems pretty remarkable.

[dkokelley]

Good point, the rate of descent might have made a difference. This sounds like a good experiment. Let's release 10 heavy balloons (just like the ones they used) in pairs of 2 at 5 different locations around the world and track where each of them land. I'm not sure what scientific purpose this would serve but it would at least satisfy my curiosity.