SIDLOC is a proposed standard for identifying and locating satellites and spacecraft. It is being developed by the Libre Space Foundation with funding from the European Space Agency.

SIDLOC is designed to be a more secure and reliable way to identify and locate satellites and spacecraft than existing methods. It uses a combination of spread spectrum radio-transmitted signals and open-source software and hardware to create a tamper-proof identification and localization system.

SIDLOC has the potential to revolutionize the way that satellites and spacecraft are managed and operated. It could make it easier to track spacecraft and prevent collisions. It could also make it easier to identify and locate spacecraft that have gone missing or become unresponsive.