The Pi balloon: a Swiss mystery

If you’ve been wondering what happened to PIE, the Raspberry Pi camera-equipped balloon Dave Akerman launched on Saturday (with considerable hinderance from me, Eben and JamesH), Dave’s blogged about the launch and its aftermath. Most exciting of all, for us, was the new record Dave bagged with this balloon: it went even higher than his original Pi in the Sky attempt, and, at 40.35km (that’s a kilometer higher than Felix Baumgartner’s jump last year), now holds the record for the highest pictures transmitted in real time from an amateur device.

Eben, holding AVA, got an unfair head start when we launched by being nearly a foot taller than me (holding PIE).

When I was a very little girl, I was given one of those mylar helium-filled balloons, and lost it almost immediately. I was comforted by my Dad, who told me a new story every day about the country he calculated the ballon must be flying over. Five-year-old me never imagined that one day, I’d get to send up a globetrotting balloon and be able to track it for real.

After flying out across East Anglia, over the North Sea, Netherlands and Germany, PIE ran out of batteries somewhere over Switzerland in the early hours of Sunday morning. Dave believes it probably burst when it reached France later that day and warmed up with the heat of the sun, which will have made the balloon expand and rise. It’s unlikely it’ll be recovered, but we’re hoping some kind soul finds it and responds to the message Dave wrote on the payload. We had a fantastic time following PIE’s adventures, and were particularly tickled when someone in Stuttgart tweeted to let us know that they’d spotted it as it floated near the city!

You can thank Clive for this one.

PIE went up with one of our prototype camera boards, which Dave had switched to the auto setting. It performed brilliantly right up until it got into the stratosphere, when it started having trouble with the very pronounced contrast between the darkness of space and the brightness of the sun. This is something we can address in tuning for later flights, but it did produce a rather wonderful artefact which looked for all the world like a giant Raspberry Pi logo in space. (Sheer serendipity: this wasn’t planned.)

I, for one, welcome our new Raspberry Overlords.

PIE wasn’t the only balloon launched from that muddy field on Saturday. Anthony Stirk ¬†launched AVA, which is the balloon Eben is holding in both pictures above. AVA burst over Austria, and the payload was recovered by a group of local high altitude ballooning (HAB) enthusiasts. And you’d have to be¬†very enthusiastic to go and fetch AVA, because it had landed 1600m up, on the peak of a snowy mountain. The Slovakian team who went up to fetch AVA (equipped with ski poles and a radio antenna) sent back some pictures which were nearly as good as PIE’s pictures from space. Click the photo to visit Anthony’s blog, and to read the whole story.

Slovakian superheroes. From left to right : Peter Vittek, AVA , Radim Mutina (OM2AMR), Juraj Marsalik (OM1AMJ), and behind the camera Brano Janicek.

Alex Eames from RasPi.TV edited the long video stream of the couple of hours around the launch down to…just the exciting bit. (There’s no sound; your speakers aren’t broken!) I am running at the end through sheer excitement, not panic.

JamesH also took some higher-resolution video of the launch, which I’ll add here when it’s available.

I’ll leave you with a picture from Andy Potter, whose message momentarily had me believing that PIE had been spotted from the ground in the Swiss Alps. Thanks to everybody, especially Dave and Anthony, for a great weekend’s ballooning!


Alex Eames (RasPi.TV) avatar

I thought I recognised JamesH on the webcam.
Looking forward to his footage. It really was a lot of fun watching and hanging out in #highaltitude I’m also impressed by the dedication of the Slovak Supermen who rescued AVA :)

liz avatar

I hope some of the people watching and tracking over the weekend got a feeling for just how much fun the whole thing was: it’s a hobby I’d love to take up when I have some more time!

Alex Eames (RasPi.TV) avatar

Must admit, I’m thinking about SDR + Pi + antenna now (as if I need another project LOL)

Ravenous avatar

For some reason that pic of Eben in the sky reminds me of a Pink Floyd album cover…

liz avatar

Apparently Meltwater’s two-year-old said “Bye bye little man!” on seeing it. Aw.

Dave Akerman avatar

:-). Do you want me to order the required 12 cylinders of hydrogen for next time? ;-)

Dave Akerman avatar

Now covered by The Register –


meltwater avatar

Was great to watch, particularly the images loading packet by packet from PIE, incredible.

Need to get a switch-mode 3V3 supply on the Pi and reduce the power requirement even more…and perhaps a monitor circuit to put it to sleep on low/cold battery.

Can’t wait to watch the next one!

Oddly, the kids didn’t seem too concerned about Eben floating off. :D

Steve Smith (G0TDJ) avatar

Although I joined the party a little late, I had lots of fun chatting in #highaltitude and decoding the 300baud packets of data. I really didn’t think I’d hear it at all. Once I’d discovered the PIE’s signal I scrambled to install DL-FLDigi with the assistance of Peter Goodall (Thanks again for your help Pete!) on Twitter and started to receive images. I used a Yaesu FT-897 and Diamond X50 Collinear for those interested.

It was great to see so many folk get involved but I really feel that more publicity was needed for radio amateurs across near Europe to be ready to contribute to the reception of the images. Also, someone at the launch purely to film/photograph the proceedings (I’d volunteer if I could get there!).

I’m very much looking forward to the next launch.

Now, is DL-FLDigi portable to Pi? Pi to Pi decode…..Hmmm

Dave Akerman avatar

Th Pi did have a switch-mode 3V3 supply. I estimated 24 hours run time and it was a bit less (their voltage drops and internal resistance increases with the cold, so they get drained more quickly). I expected the flight to be out of range after 12 hours or so hence I didn’t do anything to extend the run time.

I will look at reducing consumption a bit for next time.

The Other Peter Green avatar

I still say it isn’t a big raspberry, it’s the Star Gate monolith from 2001:

“My God… it’s full of stars”.

meltwater avatar

Yep mighty cold up there I expect.
Excellent viewing.

We can make sure the next one is put on the MagPi events section, if you know early enough.
Hopefully get more support each time.

Leo avatar

Trying hard to resist the obvious caption competition…

Dave Akerman avatar

The problem with that is that I usually don’t know that the launch can go ahead till 3-5 days before! Yes the winds are that unpredictable.

The next Pi flight will be an altitude attempt, unlike this one which wasn’t an attempt but managed to set a record anyway!

Baca'n avatar

The 2nd picture with Eben being up in the air gave me a nice LOL.



Andrew Edwards avatar

There was another balloon over the netherlands last weekend. I’ve just read this in my local newspaper. This was launched on sunday and got up to 36km. It is in dutch and this is a cut down version of the newspaper version.

Dave Akerman avatar

Ah Holland … no need for a NOTAM there I believe.

He was lucky to get that back – if it had landed outside GSM coverage he wouldn’t know the landing position – which is why post people go the radio route.

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