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. [1] For example, catalog number 1 is the Sputnik 1 launch vehicle, with the Sputnik 1 satellite having been assigned catalog number 2. [2]
Objects that fail to orbit or orbit for a short time are not catalogued. [3] The minimum object size in the catalog is 10 centimetres (3.9 in) in diameter. [4] As of October 21,2023 [update] , 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. [5] 25,717 of the objects were well tracked while 2,055 were lost. [6] In addition USSPACECOM was also tracking 16,600 analyst objects. [7] Analyst objects are variably tracked and in constant flux, so their catalog and element set data are not published. As of September 12,2023 [update] ESA estimated there were about 36,500 pieces of orbiting debris that are large enough for USSPACECOM to track. [8]
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 space-track.org, [10] which is maintained by the 18th Space Defense Squadron (18 SDS).
Initially, the catalog was maintained by NORAD. From 1985 onwards, USSPACECOM was tasked to detect, track, identify, and maintain a catalog of all human-made objects in Earth orbit. [11] In 2002, USSPACECOM was disestablished and merged with the United States Strategic Command (USSTRATCOM). However, USSPACECOM was reestablished in 2019. [12]
Before 2020, the catalog number was limited to five digits due to the TLE format limitation. In 2020, Space-Track started to provide data in CCSDS OMM (Orbit Mean-Elements Message) format, which increased the maximum catalog number to 999,999,999. [13]
The United States Space Surveillance Network (SSN) detects, tracks, catalogs and identifies artificial objects orbiting Earth, e.g. active/inactive satellites, spent rocket bodies, or fragmentation debris. The system is the responsibility of United States Space Command and operated by the United States Space Force and its functions are:
A two-line element set or three-line element set (3LE) is a data format encoding a list of orbital elements of an Earth-orbiting object for a given point in time, the epoch. Using a suitable prediction formula, the state at any point in the past or future can be estimated to some accuracy. The TLE data representation is specific to the simplified perturbations models, so any algorithm using a TLE as a data source must implement one of the SGP models to correctly compute the state at a time of interest. TLEs can describe the trajectories only of Earth-orbiting objects. TLEs are widely used as input for projecting the future orbital tracks of space debris for purposes of characterizing "future debris events to support risk analysis, close approach analysis, collision avoidance maneuvering" and forensic analysis.
Simplified perturbations models are a set of five mathematical models used to calculate orbital state vectors of satellites and space debris relative to the Earth-centered inertial coordinate system. This set of models is often referred to collectively as SGP4 due to the frequency of use of that model particularly with two-line element sets produced by NORAD and NASA.
The United States National Space Science Data Center catalogued 157 spacecraft placed into orbit by launches which occurred in 1968. The first crewed Apollo missions occurred in 1968. It was also the year in which Earth lifeforms first left low Earth orbit, during the successful Zond 5 mission to the Moon and the Zond 6 lunar mission which crashed upon return, and the year that humans first left low Earth orbit, during the successful Apollo 8 mission to the Moon.
Explorer 1 was the first American satellite to reach orbit on 31 January 1958.
The International Designator, also known as COSPAR ID, is an international identifier assigned to artificial objects in space. It consists of the launch year, a three-digit incrementing launch number of that year and up to a three-letter code representing the sequential identifier of a piece in a launch. In TLE format the first two digits of the year and the dash are dropped.
This article outlines notable events occurring in 1995 in spaceflight, including major launches and EVAs.
The following is an outline of 1983 in spaceflight.
The United States Air Force's 1st Expeditionary Space Control Squadron is a provisional squadron attached to the 21st Space Wing at Peterson Air Force Base, Colorado.
The following is an outline of 1989 in spaceflight.
The following is an outline of 1976 in spaceflight.
The following is an outline of 1987 in spaceflight.
This is a list of spaceflights launched between January and June 1961. For launches between July and December, see 1961 in spaceflight (July–December). For an overview of the whole year, see 1961 in spaceflight.
In 2015, the maiden spaceflights of the Chinese Long March 6 and Long March 11 launch vehicles took place.
Kosmos 2499 was a Russian satellite orbiting the Earth, before breaking up on January 4, 2023.
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).
10 centimeter diameter or "softball size" is the typical minimum size object that current sensors can track and 18 SPCS maintains in the catalog.