[HN Gopher] Show HN: I turned algae into a bio-altimeter and put...
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Show HN: I turned algae into a bio-altimeter and put it on a
weather balloon
Hi 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!
Author : radeeyate
Score : 82 points
Date : 2025-11-22 17:11 UTC (4 days ago)
(HTM) web link (radi8.dev)
(TXT) w3m dump (radi8.dev)
| nonameiguess wrote:
| 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.
| sbalula wrote:
| 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.
| radeeyate wrote:
| Thank you for the kind words! The fluorescence was originally
| meant to be measured with an AS7273 spectrometer (unfortunately
| bought a different one, still worked fine though), and
| measuring ~680 nm. Certainly not a great setup but it worked
| fine. Light was ambient through acrylic, and I found out far
| too late that UV blocking effects. Despite that, I feel like
| the data is still somewhat valid, maybe. I did do some testing
| with it back on earth, though I can't remember how it
| correlated.
|
| The data I have is here:
| https://github.com/radeeyate/StratoSpore/blob/main/software/...
| - just be warned that the altitude data still isn't the exact
| same as it was while in the air (GPS not working so I had to
| take it from someone else).
| ihaveajob wrote:
| This is so interesting. I have nothing to add, other than
| congratulations, and good luck on your next project.
| rncode wrote:
| the 1080p ->> 18x10 pixel compression just to yeet images over
| LoRA is honestly more impressive than the algae part
| hdjrudni wrote:
| It's amusing but I'm not sure I understand the point. Wouldn't
| it be better to use that bandwidth for more sensor data?
| radeeyate wrote:
| Image data and telemetry were sent in different messages, so
| it wasn't too much of a bottleneck. The images were about
| ~100 bytes while the telemetry was roughly 40.
| ginkgotree wrote:
| This is absurdly impressive. If you have any interest in doing
| some more flight software work in aerospace / space / missile
| systems, shoot me an email scott@orcrist.com
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