Sherwin Salemi

Weather Balloon Data Logger

In 8th grade, my science teacher decided to do a class project on proving the Earth was round by launching a weather balloon. Everyone got different roles based on their strengths, and I became part of the core electronics team due to my experience with Arduino at the time.

I designed this data logger. It used an Arduino Nano, Real Time Clock (RTC), SD card reader, accelerometer, and temperature sensor to collect timestamped data throughout the course of the flight.

The balloon was launched and recovered in June of 2021. Overall, the outcome was pretty tragic. The GoPro was covered with nearly an inch of insulation on all sides to protect it from the sub-zero temperatures of 100,000ft+ altitudes, and overheated less than 10 minutes into the flight. The video ends around the max altitude of a hobby drone.

After recovering my data logger, we found that it's data told a very interesting story. It did record data throughout the whole flight of the balloon across over 24 hours (turns out our lifting gas was of suspicious quality and didn't provide as much lift as predicted, so the flight was insanely long). But the files were fragmented implying that the power source, an insulated USB battery, was interrupted dozens of times and the extreme cold might have caused issues with the electronics. Nonetheless, it did measure temperatures as low as -21C.

The New Data Logger is a redesigned data logger made as a hat for a Raspberry Pi Zero. It has a high precision barometer capable of extremely low pressures, it can measure the voltage and current draw of two channels, has four extra analog pins, and has a spot for the Adafruit Ultimate GPS module. I programmed custom SPI drivers using WiringPi for the devices, and tested it in my fridge.

This project taught me about the importance of failsafes. The GoPro likely cooled off shortly after it overheated but did not automatically power on and resume unlike the data logger I made. It was also insanely fun, and contributed to my passion for aerospace and high altitudes. I hope to launch Weather Balloon V2 sometime soon!