BUILD YOUR OWN PICO BALLOON AND EXPLORE THE STRATOSPHERE
Send a Raspberry Pi to 30 km with a weather balloon, radio live photos back, and drive to the landing spot.
by Dave Akerman
ScienceOpen-hardware
- difficulty
- ●●●●○
- time
- a weekend-plus
- license
- GPL-2.0
- repo
- repo ACTIVE91 stars
●●●●○ · a weekend-plus · GPL-2.0 · 91 stars · repo ACTIVE
WHAT YOU’LL NEED
- Dev board / microcontroller — runs the project firmware
Partner
COMPAREE VERDICT
Pi in the Sky is the tracker that turned Raspberry Pi high-altitude ballooning into a repeatable hobby. It radios GPS position and live images via LoRa or RTTY while the balloon climbs to 30–40 km, bursts, and parachutes down. The software is mature, GPL-licensed, and well-documented by someone who has flown it dozens of times. What will waste your weekend is not the Pi — it is the regulatory maze. Most countries require you to notify aviation authorities before launch, and you need a ham radio licence to transmit. The hardware list is clear but there is no single-click BOM; you are buying a weather balloon, helium cylinder, parachute, GPS module, camera, and radio board separately. If one part is wrong or the forecast shifts, the launch scrubs. The project is for someone who has already built a few Pi things and is comfortable with SD card images and SSH. If you have never soldered or configured a Pi, start elsewhere. If you have, and you have checked the local rules, this is the most credible open-source path to edge-of-space photography without a rocket. The single biggest trap is launching without clearance and discovering mid-flight that you just violated controlled airspace.
IN THE REPO
NOT IN THE REPO
- —Software, PCB Gerbers, and schematics are in the repo under GPL-2.0.
- —There is no BOM — the docs list compatible hardware but you source your own balloon, helium, parachute, camera, and radio parts.
- —Most countries require clearance or notification to launch an unmanned balloon; the repo does not help with paperwork.
- —The code supports multiple Pi models and has live SSDV image transmission over 434 MHz LoRa or RTTY.
- —Recovery depends on a working GPS fix and your ability to track and drive to the landing zone.
- —You need a ham radio licence to transmit on the frequencies this uses in most jurisdictions.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Partner · KickstarterHeyGears G1: 10M+ colors and transparent parts in one print, plus UV printing on flat objects. Figures, parts and labels — no painting.
Gallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Check local regulations for unmanned balloon launches and confirm you need no clearance, or file for it if required.(This step blocks everything else and is the most common project-killer.)
- 2.Read the Pi in the Sky documentation to choose your tracker hardware (LoRa or RTTY, which Pi model). (The repo README and docs folder list compatible boards and GPS modules.)
- 3.Source your balloon, parachute, helium, and enclosure from a high-altitude ballooning supplier.(The repo does not provide a BOM; you are assembling the list from the docs and other flight reports.)
- 4.Flash the SD card image, configure your callsign and frequencies, and bench-test GPS lock and radio transmission indoors. (Do not skip the bench test — a bad GPS or radio config will end your flight before it starts.)
KNOWN ISSUES
- Launching without regulatory clearance is the mistake that happens before you even inflate the balloon — check your country's rules first.
- Helium purity matters; party-grade helium will not lift the payload high enough. You need welding-grade or better.
- If you lose GPS lock after launch, you lose the payload — test the GPS module outdoors with a clear sky view before flight day.
- The landing zone is wherever the wind takes it; if you cannot drive there (private land, water, mountains), you do not get it back.
- A ham radio licence is required to transmit on the frequencies this tracker uses in most countries — operating without one is illegal.
- The balloon will burst and the descent is fast; if your parachute does not deploy or tangles, the payload hits the ground hard.
Do I need a ham radio licence?
Yes, in most countries. The tracker transmits on 434 MHz or similar ISM/amateur bands, and the licence requirement depends on your jurisdiction. Check before you launch.
How high will it go?
Typical burst altitude is 30–40 km, depending on balloon size, payload weight, and helium fill. The repo docs and lift calculators help you plan this.
What if I lose the GPS signal?
You lose the payload. The tracker radios position updates; if GPS fails or you are out of radio range at landing, you have no way to find it. This is the single biggest cause of lost flights.
Can I launch anywhere?
No. Most countries require notification or clearance, especially near airports or controlled airspace. The repo does not cover the legal side — you have to research it yourself.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
Dave Akerman has flown dozens of these and the platform is GPL-licensed with flight-proven code. What would stop you from launching one — the paperwork, the helium, or just finding a clear weekend?
Dave Akerman
Dave Akerman is a UK-based electronics engineer and high-altitude ballooning pioneer who has flown dozens of Pi payloads to the stratosphere, including record-breaking flights. Pi in the Sky is the tracker platform that emerged from those flights, released as open source so others can do the same.
Keep building — related projects
Same category, picked by how close they are to this build.
FULL CADOne homemade board that can listen to almost every radio signal in the air around you
Open-hardwareScience●●●●○advanced
FULL CADA lab positioning stage costs 10,000 dollars. This one steps 50 nanometers and is open source
ScienceOpen-hardware●●●●●expert
Partner · KickstarterCodeeBot: build the robot from Lego-compatible bricks and program it by hand; a GPT tutor explains each step.
FULL CADAllsky: a Raspberry Pi camera in a weatherproof dome that films the whole night sky by itself
ScienceOpen-hardware●●●○○moderate
NO CAD FILESTinyGS — open source global satellite ground station network
Open-hardwareScience●●○○○starter
DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM1mo agoedited
Practical notes from our verification: the repo is active and the docs are detailed, but there is no official BOM or single supplier — you are sourcing the balloon, parachute, and helium yourself from HAB vendors. The software supports both LoRa (for SSDV live images) and RTTY, and the README lists compatible GPS modules and tracker boards. The single biggest surprise is that regulatory clearance is entirely on you — the repo does not link to any country's rules or forms. If you have never launched a weather balloon before, expect to spend as much time on the paperwork and supplier research as on the Pi itself.