Since a couple of years, I was thinking about launching a high altitude balloon to the stratosphere. Taking my own pictures of blue atmosphere next to the blackness of space was a dream for me:
This is a picture from south of France of the Rhone river flowing into the Mediterranean Sea taken with the RPI camera in the CONSTELLATION 1 payload from an altitude of 86000 feet! (26km)
I tried to include new experiments in the payload: testing the robustness of a display in stratospheric environment and taking full frame pictures/video in parallel with one RPI camera module.
The screen should handle extreme temperatures (-50 degrees C), deliver very high brightness images with low flickering. I have tested several OLED screen, selected the ILSOFT Oled model, then tuned the driver (sources available here) to increase the brightness and refresh rate by dividing the display height by 8 and optimising other parameters: the goal was to avoid flickering because of the camera shutter speed.
The Rasperry PI will display the flight status on this screen (altitude, external temperature, …) while the RPI camera will be recording. The temperature and brightness requirements with ILSOFT OLED have been successfully validated during the stratospheric flight! But most of the captured frames were showing flicker for the screen because of the fast shutter speed of the RPI camera during flight lighting conditions, however here are some selected good shots of the screen:
Getting my radio amateur license (F4HHV callsign) was a part of the project too (mandatory for airborne radio transmission in France). The 2nd of November we launched from Boissières (Gard, South of France) the first payload named CONSTELLATION 1 with success, it reached 89,000 feet altitude (27,000 meters) and was recovered thanks to the 144.650MHZ APRS radio tracking system from Byonics.
Hardware:
- Raspberry PI model A and its awesome camera module!
- ILSOFT Oled screen SPI breakout
- GPS uBLOX MAX-7 with active antenna from habsupplies:
- Byonics APRS MT RTG-FA with dipole antenna from byonics
- 436Mhz beacon with 1/4 wave antenna
- Adafruit Prototyping Pi Plate Kit for the motherboard (power supply) and IO to RPI
- 3 feets RocketMan parachute
- Pawan 1200g balloon from Balloon News:
- Balloonium helium cylinder from Aerovue
CONSTELLATION I payload with OLED screen, external GPS antenna and USB port for software maintenance!
Software:
- GNU/Linux Raspbian
- Fork of raspimjpeg (thanks Silvan Melchior!) for taking full sensor pictures and video in parallel without frame loss: sources available here
- Custom ILSOFT OLED SSD1315 SPI driver for OLED screen to increase luminosity and refresh rate (by lowering vertical resolution): sources available here
- Python application dedicated to flight status update on the screen and configuring uBLOX GPS in airborne mode
- DIREWOLF opensource APRS decoder:
- GNURadio for SDR radio with FunCube dongle PRO+
- gqrx (used for radio beacon triangulation)
- CUSF landing predictor (awesome flight prediction tool!) :
More technical details about the hardware/software (OLED tuned driver) will follow in a next post. This is the video of the launch and the flight:
[embedyt]//www.youtube.com/watch?v=UY_kIYyE29M&list=PLI1fqjfU7mo4CziIOoixNlQBwMHy370G6&index=2&vq=hd720[/embedyt]
The following pictures were taken from the RPI camera:
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The launch team
The launch!
Flight elevation profile
The recovered payload after its stratospheric flight
Many thanks to my wife Céline for her support during the preparation of this project 🙂
Special thanks to Alliance Expert / Christophe Tichadou to make this project comes true 
Thanks to all my friends that helped me for the launch and chasing the payload, to Chris Hillcox and people on UKHAS IRC channel for their great support.
To be notified of my next “stratospheric” experiments, follow my Twitter account :
//twitter.com/Fab4Space
