In an exciting first, we managed to successfully complete a two-way contact by bouncing a signal off a geostationary satellite. The satellite in question, Inmarsat GX-5, is stationed at an altitude of over 35,000 kilometers, and together with Dan, HB9Q, in Switzerland, we alternated between transmitting towards the satellite and receiving reflections. This first ever amateur QSO over geo satellite the remarkable capabilities of modern amateur radio technology when paired with large, high-gain dishes.

originally found on https://hackaday.com/2025/01/24/bouncing-signals-off-of-satellites-other-than-the-moon/