Have you heard of a geostationary satellite bounce?

Many of you would have heard of moon bounce, popularly known as EME or Earth-Moon-Earth contacts in which radio signals are bounced off the moon to establish two way contacts between radio amateurs on the earth. Some of you would also have heard of venus bounce or Earth-Venus-Earth contacts which have been documented only a couple of times, that too, with very high power equipment. Contacting through the transponders on satellites is now quite common. But have you heard of contacts by passive reflection over a geostationary satellite? That is what has occurred between PI9RD operating from the 25m Dish of the Dwingeloo observatory in Netherlands and HB9Q in Switzerland. Amateur radio digital signals were bounced off Inmarsat GX-5 satellite, stationed at an altitude of over 35,000 kilometers!

Mode used was Q65 in WSJT-X software suite. Q65 mode was specifically designed for extremely weak signal communication and is well-suited for overcoming the significant path losses involved in reflections of the satellite at a great distance. You may be aware that radio amateurs reflect signals off aircrafts in aircraft scatter, off rain particles in rain scatter and even off meteor trails in meteor scatter contacts. Another such exotic mode is auroral scatter from the marvellous auroral displays in polar regions. A previous milestone was a contact by DJ5AR utilizing a satellite in polar orbit at 650 kilometers altitude, achieved in 2015. Such passive reflection over the satellites may not be successful always and possibly depends on the orientation of solar panels towards the ground stations.