YL - How to work Satellites

 https://www.amsat.org/introduction-to-working-amateur-satellites/

https://www.audiobooks.com/audiobook/how-do-satellites-stay-in-space-an-audiobook-about-how-satellites-work/573082?refId=40912&msclkid=8b3d497e7354194e1ffa2fb9dee48372

https://www.amsat.org/satellite-schedules/

AO-91’s U/v FM repeater is continuously available for use by amateur stations.

https://www.amsat.org/status/    -  shows  the  status  of  all the know  sats