Balloon Environmental Sensing Takes to the Air

We have liftoff. My first Balloon Environmental Sensing test successfully “slipped the surly bonds of earth, and danced the skies on laughter-silvered wings” sending data back the whole time. First flight was at the Digital Naturalism Conference in Gamboa, Panama, featuring 10+ sensor values streaming from the balloon to an online data collection system and dashboard.

It was a big success!

This party-balloon platform is designed for inexpensive aerial environmental sensing. Balloon lofting is perfect for scientific research, educational programs, hacker workshops, technology art, as well as low-cost indoor or industrial monitoring. Is the humidity overhead the same as on the ground? Does wind speed change? Is it dusty up there? How much UV light penetrates the jungle canopy at different levels? These are all questions that can be answered with this platform.

Since advanced LTE wasn’t available in Panama and SigFox coverage was absent, I decided to use the Digital Naturalism Lab’s LoRaWAN gateway—long-range radio networking that uses very little battery power. The data collection firmware code was written in MicroPython running on a LoPy4 wireless microcontroller module from Pycom. This first set of tests used all the Pysense evaluation board sensors including light, temperature, altitude, humidity, pitch, roll and acceleration in three axis. This data was taken in real time at 30-second intervals and transmitted using LoRaWAN across Things Network servers to be displayed on a Cayenne dashboard. The Pybytes cloud platform appears promising too, I’m looking forward to exploring that more in later phases of the project.

Gamboa has one very small grocery store. It does not sell helium or any other noble gas. Luckily the generous David Bowen allowed our sensor package to hitch a ride on his drone during my first week, so up we went for initial testing. As is so often the case, even this partial test resulted in lots of changes. In this case I realized we needed a frame counter, better battery connections and voltage monitoring before flying again. A second shakedown flight on Bowen’s drone proved the value of these additions, and gave us an excellent sampling of the data to come. We also did a bunch of range testing work, which is covered in a separate blog post.

A taxi trip into Panama City brought us to Mundo de los Globos (World of Balloons) where helium tanks are available, along with 1-meter balloons in plenty of colors. With a full tank of the squeaky gas, we returned to Gamboa and I started inflating our ride to the sky.

The next morning it was time for the sensor package to take its first balloon ride, and up we went. Andy Quitmeyer got some amazing footage from his drone and Trevor Silverstein shot high-end video from the ground (coming soon). I could not have asked for a better documentation team. The balloon reached 60 meters (about 200 feet) above ground level, which was the limit of the reel line I was using for a tether.

We got great data back from this flight, and soon made a second one—this time in a large field away from balloon-eating trees. It was easy to get LoRaWAN signal from altitude since LoRa works best in line-of-sight conditions. We plan to do more with the Things Network to support the biology and ecology research in Gamboa that are spearheaded by the local Smithsonian Tropical Research Institute.

Here’s a screenshot of the data dashboard from the flight.

And a few graphs:

Another afternoon was set aside for a proper party-balloon experiment. Using a smaller battery I was able to loft the sensor package using 6 small balloons and the small amount of remaining helium. This worked too, though 7 balloons would have provided more lift and handled the wind better. Next time, more balloons!

Data from these flights can be downloaded, and the MicroPython code for the LoPy4 or FiPy can be found on my GitHub.

For the next version of the Balloon Environmental Testing platform, my plan is to explore other sensors and wireless links. I’m especially interested in UV light, air quality, wind speed and loudness. In Gamboa we talked about trying some sound recording too. As the balloon itself is silent, it’s the perfect place to record. For wireless links I’m itching to explore some new cellular low-bandwidth, low-cost protocols, LTE Cat-M and NB-IoT, because they don’t require any dedicated base stations and should work great at the altitudes needed for balloon flights. Additional plans include extended day-long flights, free flight with GPS, and maybe look at hydrogen gas but not near any kids!

The initial prototype goal was to see if the full system will work, and it does! Gamboa was a great success for this project, giving me the time, venue and documentation assistance to bring this idea to life. If you get a chance to attend the next Dinacon, I strongly recommend it. And if you’re interested in balloon sensing for any experiment, class or project, let me know!

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