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) in order of discovery to all man-made objects in Earth orbit (including rocket bodies and debris) and space probes launched from Earth. 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. The first catalogued object, catalog number 00001, is the Sputnik 1 launch vehicle, with the Sputnik 1 satellite assigned catalog number 00002.
The minimum object size in the catalog is 10 centimeters in diameter. As of June 23, 2019[update], the catalog listed 44,336 objects including 8,558 satellites launched into orbit since 1957. 17,480 of them 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
Objects that fail to orbit or orbit for a short time are not catalogued.
- International Designator
- Space debris
- Two-line element set (TLE)
- United States Space Surveillance Network
- Kelso, T.S. (January 1998). "Frequently Asked Questions: Two-Line Element Set Format". Satellite Times. Retrieved June 23, 2019.
- "SMALL SATELLITE DEBRIS CATALOG MAINTENANCE ISSUES" (PDF). NASA. October 1, 1991. Retrieved June 23, 2019.
- "SL-1 R/B Satellite details 1957-001A NORAD 1". Retrieved January 9, 2018.
- "USSTRATCOM expands SSA data on Space-Track.org". Air Force Space Command. October 10, 2018. Retrieved June 23, 2019.
- "Frequently Asked Questions". Space-Track.org. Retrieved June 23, 2019.
10 centimeter diameter or "softball size" is the typical minimum size object that current sensors can track and 18 SPCS maintains in the catalog.
- Kelso, T.S. "SATCAT Boxscore". CelesTrak. Retrieved June 23, 2019.
- Kelso, T.S. "TLE History Statistics". CelesTrak. Retrieved June 23, 2019.
- "Space debris by the numbers". ESA. January 2019. Retrieved June 23, 2019.
- "Frequently Asked Questions". Space-Track.org. Retrieved July 14, 2019.
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).
- CelesTrak Satellite Catalog (a copy of Space-Track.org catalog)