Every trackable object in Earth orbit is assigned a unique NORAD catalog number (also called a satellite catalog number or SATCAT ID).
Every trackable object in Earth orbit is assigned a unique NORAD catalog number (also called a satellite catalog number or SATCAT ID). This numbering system is maintained by the US Space Force's 18th Space Defense Squadron and is the backbone of global space situational awareness.
When a new object is detected by the Space Surveillance Network (SSN), it goes through a process before receiving a permanent catalog number.
The gap between active entries and highest ID reflects objects that have re-entered. Their catalogue numbers are retired, not reused — each is unique forever.
Alongside the NORAD number, each object also gets a COSPAR ID that encodes when and what launched it.
Several sources provide access to the NORAD catalogue — and Orbital Radar uses them to populate what you see.
Together, these two numbering systems let anyone — from military operators to amateur trackers — unambiguously identify any object. When you click a satellite on Orbital Radar, these are the IDs linking it to all known data.