Satellite Catalog Number


The Satellite Catalog Number is a sequential five-digit number assigned by United States Space Command in order of discovery to all artificial objects in Earth orbit and space probes launched from Earth. The first catalogued object, catalog number 00001, is the Sputnik 1 launch vehicle, with the Sputnik 1 satellite assigned catalog number 00002.
Objects that fail to orbit or orbit for a short time are not catalogued. The minimum object size in the catalog is 10 centimeters in diameter., the catalog listed 44,336 objects including 8,558 satellites launched into orbit since 1957. 17,480 of the objects were actively tracked while 1,335 were lost. ESA estimates there are about 34,000 orbiting debris of the size USSTRATCOM is capable to track as of January 2019.
Permanently catalogued objects are assigned numbers in 1-69999 range. The catalog is expected to transition to 9-digit catalog numbers in 2020.
Space Command shares the catalog via space-track.org website. 18th Space Control Squadron is the unit that maintains the catalog.

History

Initially the catalog was maintained by NORAD but starting from 1985 USSPACECOM was tasked to detect, track, identify, and maintain a catalog of all man-made objects in Earth orbit. In 2002 USSPACECOM was merged with USSTRATCOM, but it later regained independence in 2019.