weather balloon flights with an EZIE-Mag magnetometer, and the hunt for 24 lost miles of GPS track
In 2023 I designed, built, and launched a scientific weather balloon payload around an EZIE-Mag, the magnetometer kit from the outreach program for NASA’s EZIE mission at JHU APL. The launch went through the University of Maryland’s Nearspace program. The payload came back. The GPS track didn’t, at least not all of it: there was a 20 mile gap right in the middle of the flight.
I spent an independent study at JHU trying to reconstruct the missing positions from the data I did have. Kalman filter research, double integration of the accelerometer, then single integration using ground speed with midpoint updates, with proper geodetic to ECEF coordinate transforms so Earth’s curvature didn’t bite me. The estimates kept drifting off axis, and the root cause turned out to be physical, not mathematical: the accelerometer sampled too slowly to capture how violently the wind was throwing the payload around. My advisor and I decided the reconstruction wasn’t accurate enough to publish, which was its own lesson.
Everything from the project lives in EZIE-Balloon-Public. The repo started out empty and as of June 2026 is built out into a complete project archive:
The raw .rawz flight data files were left out on purpose. The EZIE section of peterseelman.com links to this repo and to a published wiki note.
Anyone editing this page later: it is published. New detail about what the repo holds is fine, but keep personal and identifying material out, the same way the public repo was prepared.