Definitions
Ground-based optical observations of the orbital debris environment
The New McKnight Top 50 (2022) - the 50 statistically most concerning derelict objects in LEO. Source: A Map of the Statistical Collision Risk in LEO:https://www.researchgate.net/publication/369359688_A_Map_of_the_Statistical_Collision_Risk_in_LEO
McKnight Top 50 - the 50 statistically most concerning derelict objects in LEO.Source: GitHub IBM Space Tech - Space Situational Awareness:https://github.com/IBM/spacetech-ssa/blob/master/docs/iss_top50.md
INTERNATIONAL IDENTIFIERS FOR ARTIFICIAL OBJECTS IN SPACE:
The Committee on Space Research (COSPAR) of the International Science Council (ISC) has created the international designator for identifying artificial objects in space, known as COSPAR ID. 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.
The Satellite Catalog Number SATCAT or NORAD (North American Aerospace Defense) Catalog Number, NORAD ID, USSPACECOM object number or simply catalog number, created in the order of launch or discovery to all artificial objects in the orbits of Earth and those that left Earth's orbit.
SPACE DEBRISEncompasses both natural meteoroid and artificial (human-made) orbital debris. Meteoroids are in orbit about the sun, while most artificial debris is in orbit about the Earth (hence the term “orbital” debris).
Source: NASA
ORBITAL DEBRISIs the term for any object in Earth orbit that no longer serves a useful function. These objects include non-operational spacecraft, derelict launch vehicle stages, mission-related debris, and fragmentation debris.
NON-OPERATIONAL SPACECRAFTOf the more than 6,800 spacecraft placed into Earth orbit since the 1957 launch of Sputnik 1, approximately 2,400 non-operational spacecraft are still in Earth orbit. Now considered orbital debris, these objects vary in size. Picosats and microsats may be small, weighing only a kilogram, but massive objects remain in orbit beyond their lifetimes as well. Geosynchronous spacecraft can be several metric tons. Small or large, these objects pose potentially mission ending threats to operational spacecraft.
DERELICT LAUNCH VEHICLE STAGESMore than half a century has passed since the first launch vehicle stage was placed into Earth orbit. More than 30 percent—approximately 1,700—of the launch vehicle stages used since then remain in Earth orbit. Such debris can be as small as 100 kilograms (or even less) and as large as 8 metric tons.
MISSION-RELATED DEBRISDebris can be generated during the launch and satellite-deployment processes. Items such as sensor and engine covers, straps, springs, and yo-yo despin weights were frequently jettisoned into Earth orbit during the 1960s and 1970s. Such debris was typically created during the first day or within the first few weeks of launch. Today, design modifications on spacecraft and launch vehicles have virtually eliminated such potential for orbital debris.
FRAGMENTATION DEBRISMost of the debris in Earth orbit results from the fragmentation of spacecraft and rocket bodies on orbit after their mission has been completed. Fragmentation is generally due to one of three things: anomalous events, explosions, or collisions. Most are accidental, and can occur 25 hours after successful completion of the mission—or 25 years later. Guidelines and standards created by NASA, the U.S., and other nations seek to eliminate or limit the occurrence of satellite fragmentation of any kind.
Source: NASA - Orbital Debris Management and Risk Mitigation
SPACECRAFTVehicles, payloads, and other man-made objects that are designed to for placement or operation in outer space. For example, spacecraft include satellites, inhabitable space stations, inhabitable capsules, and cargo vehicles.
SPACE DEBRISThe IADC defines Space Debris as “all man-made objects including fragments and elements thereof, in Earth orbit or re-entering the atmosphere, that are non-functional.”49 The FAA agrees with the IADC definition of space debris and refines the debris issue further by establishing the size of debris applicable for regulation. “Orbital debris” would be defined as all human-generated debris in Earth orbit that is greater than 5 mm in any dimension. The FAA proposes 5 mm as the threshold size because an object of that size, traveling at 10 km per second, a speed typical of objects on orbit, can incapacitate a functioning satellite, which in turn may contribute to the creation of more debris. Most active satellites on orbit are protected against small pieces of debris and micrometeoroids less than 5 mm in size with shielding or thermal blankets.
Source: FAA - Mitigation Methods for Launch Vehicle Upper Stages on the Creation of Orbital Debris 2023, Orbital-Debris_NPRM-Issuance
DISPOSAL An end-of-mission process for moving a spacecraft (if necessary) to an orbit considered acceptable for orbital debris limitation.
LOW EARTH ORBITAn orbit with a mean altitude less than or equal to 2,000 km, or equivalently, an orbit with a period less than or equal to 127 minutes.
METEOROIDS. Naturally occurring particulates associated with solar system formation or evolution processes. Meteoroid material is often associated with asteroid breakup or material released from comets.
ORBITAL DEBRIS Artificial objects, including derelict spacecraft and spent launch vehicle orbital stages, left in orbit which no longer serve a useful purpose. In this document, only debris of diameter 1 mm and larger is considered. If liquids are to be released, they should explicitly be shown to be compliant with all mitigation requirements.
ORBITAL LIFETIMEThe length of time an object remains in orbit. Objects in LEO or passing through LEO lose energy as they pass through the Earth’s upper atmosphere, eventually getting low enough in altitude that the atmosphere removes them from orbit.
ORBITAL STAGEA part of the launch vehicle left in a parking, transfer, or final orbit (excluding solar/interplanetary orbits with no potential intercept with Earth) during or after payload insertion; includes liquid propellant systems, solid rocket motors, and any propulsive unit jettisoned from a spacecraft.
PASSIVATION The process of removing stored energy from a space structure which could credibly result in eventual generation of new orbital debris after End of Mission. This includes removing energy in the form of electrical, pressure, mechanical, or chemical.
SPACECRAFTThis includes all components contained within or attached to a space borne payload such as instruments and fuel.
SPACE DEBRIS General class of debris, including both meteoroids and orbital debris.
SPACE STRUCTURES Launch vehicle components, upper stages, spacecraft, and other payloads.
STABILIZEDWhen the spacecraft maintains its orientation along one or more axes.
Source: NASA Process for Limiting Orbital Debris NASA-STD-8719.14C
McKnight Top 50 - the 50 statistically most concerning derelict objects in LEO.Source: GitHub IBM Space Tech - Space Situational Awareness:https://github.com/IBM/spacetech-ssa/blob/master/docs/iss_top50.md
Definitions:
INTERNATIONAL IDENTIFIERS FOR ARTIFICIAL OBJECTS IN SPACE:
The Committee on Space Research (COSPAR) of the International Science Council (ISC) has created the international designator for identifying artificial objects in space, known as COSPAR ID. 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.
The Satellite Catalog Number SATCAT or NORAD (North American Aerospace Defense) Catalog Number, NORAD ID, USSPACECOM object number or simply catalog number, created in the order of launch or discovery to all artificial objects in the orbits of Earth and those that left Earth's orbit.
SPACE DEBRISEncompasses both natural meteoroid and artificial (human-made) orbital debris. Meteoroids are in orbit about the sun, while most artificial debris is in orbit about the Earth (hence the term “orbital” debris).
Source: NASA
ORBITAL DEBRISIs the term for any object in Earth orbit that no longer serves a useful function. These objects include non-operational spacecraft, derelict launch vehicle stages, mission-related debris, and fragmentation debris.
NON-OPERATIONAL SPACECRAFTOf the more than 6,800 spacecraft placed into Earth orbit since the 1957 launch of Sputnik 1, approximately 2,400 non-operational spacecraft are still in Earth orbit. Now considered orbital debris, these objects vary in size. Picosats and microsats may be small, weighing only a kilogram, but massive objects remain in orbit beyond their lifetimes as well. Geosynchronous spacecraft can be several metric tons. Small or large, these objects pose potentially mission ending threats to operational spacecraft.
DERELICT LAUNCH VEHICLE STAGESMore than half a century has passed since the first launch vehicle stage was placed into Earth orbit. More than 30 percent—approximately 1,700—of the launch vehicle stages used since then remain in Earth orbit. Such debris can be as small as 100 kilograms (or even less) and as large as 8 metric tons.
MISSION-RELATED DEBRISDebris can be generated during the launch and satellite-deployment processes. Items such as sensor and engine covers, straps, springs, and yo-yo despin weights were frequently jettisoned into Earth orbit during the 1960s and 1970s. Such debris was typically created during the first day or within the first few weeks of launch. Today, design modifications on spacecraft and launch vehicles have virtually eliminated such potential for orbital debris.
FRAGMENTATION DEBRISMost of the debris in Earth orbit results from the fragmentation of spacecraft and rocket bodies on orbit after their mission has been completed. Fragmentation is generally due to one of three things: anomalous events, explosions, or collisions. Most are accidental, and can occur 25 hours after successful completion of the mission—or 25 years later. Guidelines and standards created by NASA, the U.S., and other nations seek to eliminate or limit the occurrence of satellite fragmentation of any kind.
Source: NASA - Orbital Debris Management and Risk Mitigation
SPACECRAFTVehicles, payloads, and other man-made objects that are designed to for placement or operation in outer space. For example, spacecraft include satellites, inhabitable space stations, inhabitable capsules, and cargo vehicles.
SPACE DEBRISThe IADC defines Space Debris as “all man-made objects including fragments and elements thereof, in Earth orbit or re-entering the atmosphere, that are non-functional.”49 The FAA agrees with the IADC definition of space debris and refines the debris issue further by establishing the size of debris applicable for regulation. “Orbital debris” would be defined as all human-generated debris in Earth orbit that is greater than 5 mm in any dimension. The FAA proposes 5 mm as the threshold size because an object of that size, traveling at 10 km per second, a speed typical of objects on orbit, can incapacitate a functioning satellite, which in turn may contribute to the creation of more debris. Most active satellites on orbit are protected against small pieces of debris and micrometeoroids less than 5 mm in size with shielding or thermal blankets.
Source: FAA - Mitigation Methods for Launch Vehicle Upper Stages on the Creation of Orbital Debris 2023, Orbital-Debris_NPRM-Issuance
DISPOSAL An end-of-mission process for moving a spacecraft (if necessary) to an orbit considered acceptable for orbital debris limitation.
LOW EARTH ORBITAn orbit with a mean altitude less than or equal to 2,000 km, or equivalently, an orbit with a period less than or equal to 127 minutes.
METEOROIDS. Naturally occurring particulates associated with solar system formation or evolution processes. Meteoroid material is often associated with asteroid breakup or material released from comets.
ORBITAL DEBRIS Artificial objects, including derelict spacecraft and spent launch vehicle orbital stages, left in orbit which no longer serve a useful purpose. In this document, only debris of diameter 1 mm and larger is considered. If liquids are to be released, they should explicitly be shown to be compliant with all mitigation requirements.
ORBITAL LIFETIMEThe length of time an object remains in orbit. Objects in LEO or passing through LEO lose energy as they pass through the Earth’s upper atmosphere, eventually getting low enough in altitude that the atmosphere removes them from orbit.
ORBITAL STAGEA part of the launch vehicle left in a parking, transfer, or final orbit (excluding solar/interplanetary orbits with no potential intercept with Earth) during or after payload insertion; includes liquid propellant systems, solid rocket motors, and any propulsive unit jettisoned from a spacecraft.
PASSIVATION The process of removing stored energy from a space structure which could credibly result in eventual generation of new orbital debris after End of Mission. This includes removing energy in the form of electrical, pressure, mechanical, or chemical.
SPACECRAFTThis includes all components contained within or attached to a space borne payload such as instruments and fuel.
SPACE DEBRIS General class of debris, including both meteoroids and orbital debris.
SPACE STRUCTURES Launch vehicle components, upper stages, spacecraft, and other payloads.
STABILIZEDWhen the spacecraft maintains its orientation along one or more axes.
Source: NASA Process for Limiting Orbital Debris NASA-STD-8719.14C