This article needs additional citations for verification
. (December 2017)
The Satellite Catalog Number (also known as NORAD Catalog Number, NORAD ID, NASA catalog number, USSPACECOM object number or simply catalog number and similar variants) is a sequential 5-digit number assigned by USSPACECOM (United States Space Command) to all Earth orbiting satellites in order of identification. Before USSPACECOM, the catalog was maintained by NORAD. The first catalogued object, catalog number 00001, is the Sputnik 1 launch vehicle, with the Sputnik 1 satellite assigned catalog number 00002.
As of August 2017National Space Science Data Center Master Catalog listed more than 42,900 tracked objects including more than 7,800 satellites launched into orbit since 1957.