Space debris — any space object including spacecraft or fragments and elements thereof in Earth's orbit or re-entering Earth's atmosphere, that are non-functional or no longer serve any specific purpose, including parts of rockets or artificial satellites, or inactive artificial satellites (3)

Space object — any man-made object in outer space (1)

Spacecraft — any space object serving a specific purpose, including active artificial satellites and launcher upper stages (2)

SST data — physical parameters of space objects acquired by SST sensors or orbital parameters of space objects derived from SST sensors' observations (5)

SST information — processed SST data which is readily meaningful to the recipient (6)

SST sensor — a device or a combination of devices, such as ground-based or space-based radars and telescopes, that is able to measure physical parameters related to space objects, such as size, location and speed (4)