Weather Balloon — ALR goes to Space

A school project with the Luxembourg Institute of Science and Technology: build a payload capable of measuring the atmosphere on the way up, put it under a weather balloon, and get it back.

It launched at 14:06 on 14 September 2024 from Atert-Lycée Redange. Roughly two hours later it came down near Verdun, in France, and everything was recovered intact — the GoPro, the payload and the data.

I did the programming and the PCB design. Ben Kasel handled mentoring, organisation and troubleshooting; Christophe Mayers did soldering and documentation.

The board is an atmospheric data acquisition system: temperature and air quality as the primary measurements, with motion detection, a gamma-ray detector and GPS providing position and a reliable clock to timestamp everything against.

Data is written to a micro SD card during the flight, which is the only sensible choice when the recovery point is unknown and the alternative is a radio link you cannot guarantee. A GoPro rode along and filmed the climb.

A balloon flight is unforgiving in a quiet way. There is no telemetry to reassure you and no second attempt that afternoon: either the board survives the cold and the pressure drop and keeps writing, or you land two hours away with an empty card.

It was the first project where the electronics had to work unattended, far from anyone who could fix them — the same constraint that every later project has been a version of.