Which is generally believed to have been a radiosonde launched by hobbyists in the US: https://www.npr.org/2023/02/18/1158048921/pico-balloon-k9yo https://www.

Which is generally believed to have been a radiosonde launched by hobbyists in the US: https://www.npr.org/2023/02/18/1158048921/pico-balloon-k9yo https://www.npr.org/2023/02/18/1158048921/pico-balloon-k9yo