Show HN: I turned algae into a bio-altimeter and put it on a weather balloon
radi8.devHi HN - My name is Andrew, and I'm a high school student.
This is a write-up on StratoSpore, a payload I designed and launched to the stratosphere. The goal was to test if we could estimate physical altitude based on algae fluorescence (using a lightweight ML model trained on the sensor data).
The blog post covers the full engineering mess/process, including:
- The Hardware: Designing PCBs for the AS7263 spectral sensor and Pi Zero 2 W.
-The biological altimeter: How I tried to correlate biological stress (fluorescence) with altitude.
- The Communications: A custom lossy compression algorithm I wrote to smash 1080p images down to 18x10 pixels so I could transmit them over LoRA (915 Mhz) in semi-real-time.
The payload is currently lost in a forest, but the telemetry data survived. The code and hardware designs are open source on GitHub: https://github.com/radeeyate/stratospore
I'm happy to answer technical questions about the payload, software, or anything else you are curious about! Critique also appreciated!
Congrats on the interesting project! I was curious to know more about the scientific payload: how did you measure the fluorescence? Did you apply excitation light continuously? Or did you rely on ambient light and correct for it when measuring fluorescence? Did you have a control on earth to compensate for any biological related effects? UV and even blue light can stress or even kill cells, or bleach the fluorescence proteins. How do you expect altitude to influence fluorescence? It would be great to look at some data (could not find it on the blog, or github). Acrylic blocks a substancial portion of the UV light!
Edit: Definetely agree with other comment that the whole experience is more important than these details.
It's great that opportunities like this exist. Doing a project like this at all is such valuable experience. You must have learned a ton and can take that with you for all future projects. The only real quibble is the experimental setup is not really scientifically valid. UV light on its own kills algae, so you're going to detect a monotonic effect roughly equivalent to the altitude increase assuming a reasonably constant rate of altitude increase just from the cumulative exposure. That's not the same thing as detecting a change purely because of altitude.
Who cares, though? Scientists train for many years to learn the details of experimental methods in their specific domain. The engineering and hacking experience on its own is what really matters here.
This is so interesting. I have nothing to add, other than congratulations, and good luck on your next project.