Fun writeup! I was surprised by the part about styrofoam boxes though:

  Despite their popularity, they have a few disadvantages:

  They come in predefined sizes which mandate a certain weight allowance
  They cannot be flexible for your specific payload, making it hard to be efficient with payload layout
  They are expensive compared to more custom solutions

This shocks me, as styrofoam is one of the easiest materials in the world to cut, shape, fasten, and customize to your heart's content. I'm all for 3d printing stuff, but in the theater world we build a ton of very detailed (and shockingly durable) stuff out of foam all the time....

Buying a styrofoam box and just accepting that it's gotta be that shape and size feels like a huge waste.

I think another point I hadn't included was the flexibility I had with prototyping different boxes. The hardware was changing all the time, and being able to just 3d print another revision was very convenient.

If I did something like that with styrofoam, it probably would have gotten pretty expensive. The precision you get from printing was also a plus, as there needed to be slots for cameras, antennas, and circuit board mounting holes.

You can get a 4' x 8' sheet of 1" EPS insulation from Home Depot for under $20 (thicker available if you need it, costs more) along with compatible construction adhesives.

You do have to be careful with glue selection because a lot of solvents will dissolve it, but there's plenty that will work.

What's expensive? You can buy a medium sized cooler for $5 at Walmart. That's a fair bit of foam.

Seems like the simple solution is a Styrofoam sheet, a $10 hot knife and some glue solves the customization problem almost trivially.

In my intro Industrial Design class long ago we fashioned styrofoam and many other kinds of foam into every shape imaginable with a hot wire, some utility knives, and contact adhesive. A wood rasp worked well for organic and rounded forms (wear a mask), though that’s probably not needed in this application.

I live in Montana and routinely hunt the Musselshell river valley/Meagher county area. It's maybe my favorite place in the world. So few folks have been there, but spend some time there and you might just find yourself feeling depressed when you leave and not knowing why.

Glad to see other folks go through the area. The wind in Judith Gap is insane, so I'm surprised that you never found it. I'll keep an eye out when I'm out there in Sept/Oct.

Must have been a UAP.

Impressive level of detail, impressive work for anyone, much less high school students.

Wait, so at 28k/km the temp goes up to 15C?

This is all very cool but this temperature reading caught my eye as unexpected.

I found that surprising too! This probably isn't a completely accurate number, as the sensor is black and likely experienced some heating from the sun. Something also worth noting is that different layers of the atmosphere experience different temperatures www.noaa.gov/jetstream/atmosphere/layers-of-atmosphere

Amazing. I love that i didn't know this. When i was studying weather as part of my pilots license i noted the basic mental math that i'd lose ~2 degrees celsius per 1000ft, but never did i take a second to ask, what happens when i go up 28,000 km.

the article says 28.42 km. where are you seeing 28000 km ?

yeah i have no idea why my brain decided to type that (twice...), its clearly 28km

The images seem a bit scrambled, presumably due to missing data blocks. At that low a resolution, have you considered maybe Robot36 SSTV?

Images are all in order, but some have missing packets.

The problem with SSTV is the power required. From some looking it seems that transmitting would need at least 5 watts. This wouldn't be feasible running on the balloon, as it was powered by Energizer Ultimate Lithium batteries.

Oh, yeah FM transmitters can require a fair bit of power.

What is it using then, LoRA type stuff?

Yep, the radio link runs LoRa on the 33 cm band (915 MHz)