A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never more than about one-third of the radius of Earth.
The Space-Based Infrared System (SBIRS) is a United States Space Force system intended to meet the United States' Department of Defense infrared space surveillance needs through the first two to three decades of the 21st century. The SBIRS program is designed to provide key capabilities in the areas of missile warning, missile defense, battlespace characterization and technical intelligence via satellites in geosynchronous Earth orbit (GEO), sensors hosted on satellites in highly elliptical orbit (HEO), and ground-based data processing and control.
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.
Surrey Satellite Technology Ltd, or SSTL, is a company involved in the manufacture and operation of small satellites. A spin-off company of the University of Surrey, it is presently wholly owned by Airbus Defence and Space.
The Space Fence is a second-generation space surveillance system operated by the United States Space Force in order to track artificial satellites and space debris in Earth orbit.
The Satellite Catalog Number is a sequential nine-digit number assigned by the United States Space Command (USSPACECOM) in the order of launch or discovery to all artificial objects in the orbits of Earth and those that left Earth's orbit. The first catalogued object, catalog number 1, is the Sputnik 1 launch vehicle, with the Sputnik 1 satellite having been assigned catalog number 2. Objects that fail to orbit or orbit for a short time are not catalogued. The minimum object size in the catalog is 10 centimetres (3.9 in) in diameter. As of October 21, 2023, 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. 25,717 of the objects were well tracked while 2,055 were lost. In addition USSPACECOM was also tracking 16,600 analyst objects. Analyst objects are variably tracked and in constant flux, so their catalog and element set data are not published. As of September 12, 2023 ESA estimated there were about 36,500 pieces of orbiting debris that are large enough for USSPACECOM to track.
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.
Spacecraft collision avoidance is the implementation and study of processes minimizing the chance of orbiting spacecraft inadvertently colliding with other orbiting objects. The most common subject of spacecraft collision avoidance research and development is for human-made satellites in geocentric orbits. The subject includes procedures designed to prevent the accumulation of space debris in orbit, analytical methods for predicting likely collisions, and avoidance procedures to maneuver offending spacecraft away from danger.
The 1st Space Operations Squadron is a United States Space Force unit responsible for space-based space domain awareness. Located at Schriever Space Force Base, Colorado, the squadron operates the Space Based Space Surveillance system, the Advanced Technology Risk Reduction system, the Operationally Responsive Space-5 satellite, and the Geosynchronous Space Situational Awareness Program.
The Near Earth Object Surveillance Satellite (NEOSSat) is a Canadian microsatellite using a 15-cm aperture f/5.88 Maksutov telescope, with 3-axis stabilisation giving a pointing stability of ~2 arcseconds in a ~100 second exposure. It is funded by the Canadian Space Agency (CSA) and Defence Research and Development Canada (DRDC), and searches for interior-to-Earth-orbit (IEO) asteroids, at between 45 and 55 degree solar elongation and +40 to -40 degrees ecliptic latitude.
The Space Tracking and Surveillance System (STSS) was a pair of satellites developed by the United States Missile Defense Agency (MDA) to research the space-based detection and tracking of ballistic missiles. Data from STSS satellites could allow interceptors to engage incoming missiles earlier in flight than would be possible with other missile detection systems. The STSS program began in 2001, when the "SBIRS Low" program was transferred to MDA from the United States Air Force. In December 2002, SBIRS Low Research & Development was renamed Space Tracking and Surveillance System (STSS).
Project Space Track was a research and development project of the US Air Force, to create a tracking system for all artificial satellites of the Earth and space probes, domestic and foreign.
Space domain awareness is the study and monitoring of satellites orbiting the Earth. It involves the detection, tracking, cataloging and identification of artificial objects, i.e. active/inactive satellites, spent rocket bodies, or fragmentation debris.
The Space Surveillance Telescope (SST) is a Southern Hemisphere based U.S. Space Force telescope used for detecting, tracking and cataloguing satellites, near-Earth objects and space debris.
NEO Surveyor, formerly called Near-Earth Object Camera (NEOCam), then NEO Surveillance Mission, is a planned space-based infrared telescope designed to survey the Solar System for potentially hazardous asteroids.
Sapphire is a Canadian space surveillance satellite which was launched in 2013. Sapphire was commissioned and integrated by MacDonald, Dettwiler and Associates (MDA) based on an SSTL-150 bus produced by Surrey Satellite Technology (SSTL) and an optical payload produced by COM DEV International.
Eglin AFB Site C-6 is a United States Space Force radar station which houses the AN/FPS-85 phased array radar, associated computer processing system(s), and radar control equipment. Commencing operations in 1969, the AN/FPS-85 was the first large phased array radar. The entire radar/computer system is located at a receiver/transmitter building and is supported by the site's power plant, fire station, 2 water wells, and other infrastructure for the system. As part of the US Space Force's Space Surveillance Network its mission is to detect and track spacecraft and other manmade objects in Earth orbit for the Combined Space Operations Center satellite catalogue. With a peak radiated power of 32 megawatts the Space Force claims it is the most powerful radar in the world, and can track a basketball-sized object up to 22,000 nautical miles (41,000 km) from Earth.
The Space Safety Programme, formerly the Space Situational Awareness (SSA) programme, is the European Space Agency's (ESA) initiative to monitor hazards from space, determine their risk, make this data available to the appropriate authorities and where possible, mitigate the threat.
Beam park is a radar mode used for space surveillance, particularly tracking space debris. In beam-park mode, a radar beam is kept in a fixed direction with respect to the Earth, while objects passing through the beam are tracked. In 24 hours, as a result of the Earth’s rotation, the radar effectively scans a narrow strip through 360° of the celestial sphere. The scattered waves are detected by a receiver and the measurements obtained during the observations can be used to determine object radar cross-section, time of peak occurrence, polarization ratio, doppler shift and object rotation. The obtained information for each object is then processed and matched against data from previously catalogued objects. The beam-park mode can be used to detect both previously known and uncatalogued objects at any altitude, provided that the reflected power captured by the receiver can be distinguished from the noise. This limits the use of radar-based beam park observations to objects in Low-Earth Orbit (LEO). Optical instruments, in turn, have very good performance for objects in Geostationary Earth Orbit (GEO) and in Geostationary Transfer Orbit (GTO). The radar technique typically outperforms optical facilities in LEO and can conduct observations for longer periods, both during day and night, independently of the weather and object illumination by sunlight.
Asteroid impact prediction is the prediction of the dates and times of asteroids impacting Earth, along with the locations and severities of the impacts.
