At the 42$^{\rm{nd}}$ international balloon festival in Château-d’Oex, 25 January to 2 February, 2020, one balloon flight was special.
Manned by two students from Fribourg, the speaker, and a prize-winning pilot of the international Gordon-Bennett cup 2019,
a balloon ascended to 4000~m~asl, commemorating a pioneering flight measuring cosmic rays.
Using 21$^{\textrm{st}}$ century technology the flux of cosmic rays increasing with altitude was verified. This article tells the story behind this event and what circumstances made it possible.