Satellite Catalog Number

{{Short description|NORAD satellite identifier}}

{{Use American English|date=November 2020}}

The Satellite Catalog Number (SATCAT), also known as NORAD Catalog Number, NORAD ID, USSPACECOM object number, is a sequential nine-digit number assigned by the United States Space Command (USSPACECOM), and previously the North American Aerospace Defense Command (NORAD), in the order of launch or discovery to all artificial objects in the orbits of Earth and those that left Earth's orbit.{{cite web |url=https://celestrak.org/columns/v04n03/ |title=Frequently Asked Questions: Two-Line Element Set Format |first=T.S. |last=Kelso |work=Satellite Times |date=January 1998 |access-date=June 23, 2019}} For example, catalog number 1 is the Sputnik 1 launch vehicle, with the Sputnik 1 satellite having been assigned catalog number 2.{{cite web |url=https://www.n2yo.com/satellite/?s=1 |title=SL-1 R/B Satellite details 1957-001A NORAD 1 |access-date=January 9, 2018}}

Objects that fail to orbit or orbit for a short time are not catalogued.{{cite web |url=https://www.space-track.org/documentation#/faq |title=Frequently Asked Questions |access-date=July 14, 2019 |publisher=Space-Track.org |quote=Q: What criteria are used to determine whether an orbiting object should receive a catalogue number and International Designation? A: We must be able to determine who it belongs to, what launch it correlates to, and the object must be able to be maintained (tracked well).}} The minimum object size in the catalog is {{convert|10|cm}} in diameter.{{cite web |url=https://www.space-track.org/documentation#/faq |title=Frequently Asked Questions |access-date=June 23, 2019 |publisher=Space-Track.org |quote=10 centimeter diameter or "softball size" is the typical minimum size object that current sensors can track and 18 SPCS maintains in the catalog.}} {{As of|2023|10|21|df=US}}, the catalog listed 58,010 objects, including 16,645 satellites that had been launched into orbit since 1957 of which 8,936 were still active.{{cite web |url=https://celestrak.org/satcat/boxscore.php |title=SATCAT Boxscore |publisher=CelesTrak |first=T.S. |last=Kelso |access-date=Oct 21, 2023}} 25,717 of the objects were well tracked while 2,055 were lost.{{cite web |url=https://celestrak.org/NORAD/elements/history.php |title=TLE History Statistics |access-date=Oct 21, 2023 |publisher=CelesTrak |first=T.S. |last=Kelso}} In addition USSPACECOM was also tracking 16,600 analyst objects.{{cite web |url=https://www.space-track.org |title=Space-Track.org Space Scoreboard |access-date=Nov 15, 2022 |publisher=Space-Track.org}} Analyst objects are variably tracked and in constant flux, so their catalog and element set data are not published. {{as of|2023|09|12|df=US}} ESA estimated there were about 36,500 pieces of orbiting debris that are large enough for USSPACECOM to track.{{cite web |url=https://www.esa.int/Our_Activities/Space_Safety/Space_Debris/Space_debris_by_the_numbers |publisher=ESA |title=Space debris by the numbers |date=12 September 2023 |access-date=21 October 2023}}

class="wikitable" |+Ranges reserved for temporary, reused numbers{{cite tweet|user=TSKelso|number=1798509642508857543|title=18 SDS just assigned NORAD Catalog Number 60011.|date=5 June 2024|access-date=7 June 2024}} !From !To !Description

70,000 |79,999 |Expected post-launch orbits.

80,000 |89,999 |Analyst objects. Objects tracked with insufficient fidelity and objects not associated with a known launch.

90,000 |99,999 |Uncorrelated tracks.

270,000 |339,999 |Additional analyst objects. The range will be released for permanent objects in the future.

700,000,000 |899,999,999 |Reserved for internal use by various systems.

900,000,000 |999,999,999 |Uncorrelated tracks.

Space Command shares the catalog via [https://space-track.org space-track.org],{{cite web |url=https://www.afspc.af.mil/News/Article-Display/Article/1658619/usstratcom-expands-ssa-data-on-space-trackorg/ |archive-url=https://web.archive.org/web/20181014121211/https://www.afspc.af.mil/News/Article-Display/Article/1658619/usstratcom-expands-ssa-data-on-space-trackorg/ |url-status=dead |archive-date=October 14, 2018 |publisher=Air Force Space Command |date=October 10, 2018 |access-date=June 23, 2019 |title=USSTRATCOM expands SSA data on Space-Track.org}} which is maintained by the 18th Space Defense Squadron (18 SDS).