Balloon magnetometry

The goal of this project is to measure the magnetic field at high-altitudes 60kft to 100kft. The Earth’s magnetic field is typically not measured at these altitudes, it’s usually measured with satellites or low-altitude (<10kft) aircraft for anomaly surveys.

The goal is to build a pico-balloon payload that can circumnavigate the Earth using a low power tracker and a PNI RM3100 magnetometer. We had an opportunity to launch the first version of the payload during the total eclipse in April 2024, Section 4, but we lost contact with the payload telemetry.

Balloon in progress 2025-11-06

Currently aloft!. Track it here

Launches

Pico-balloon payload

Testing with HF antenna and raspberry pi

Tested outside with a 20 meter band HF antenna and made a (one!) successful WSPR contact. I set up a raspberry pi with a battery pack to power the u4b so that I can log in and monitor the u4b from inside the house.

https://WSPRnet.org map page showing successful contact.

Set up in backyard. Raspberry Pi as USB host for u4b so that I can sit in air-conditioned luxury and monitor things.

GPS dipole antenna

I’m developing a new payload based on QRP labs u4b balloon tracker. So far I’ve tested mine with a GPS dipole antenna.

u4b with GPS antenna

Eclipse launch

Test payload (Eclipse Chipse for scale)

Flight payload

Launch

Recovery

Balloon payload

Tracker/telemetry/microcontroller

Several options exist

LoRA/LoRAWAN trackers

This option does not require an amateur radio license, instead using LoRA to connect to the Things Network or the Helium network. These are line of sight trackers. The Things Network in the US appears to be quite limited.

https://github.com/lightaprs/LightTracker-1.1

A version was built around this system and flown in 2024 during the total eclipse.

APRS

VHF

• https://qrp-labs.com/lightaprs2.html

WSPR

• https://www.zachtek.com/product-page/wspr-tx-pico-transmitter
• https://qrp-labs.com/lightaprsw2.html
• https://qrp-labs.com/u4b