United States Space Surveillance Network The United States Space Surveillance Network detects , tracks , catalogs and identifies artificial objects orbiting Earth , i . e . active / inactive satellites , spent rocket bodies , or fragmentation debris . The system is the responsibility of the Joint Functional Component Command for Space , part of the United States Strategic Command ( USSTRATCOM ) . Space surveillance accomplishes the following : The SPACETRACK program represents a worldwide Space Surveillance Network ( SSN ) of dedicated , collateral , and contributing electro - optical , passive radio frequency ( rf ) and radar sensors . The SSN is tasked to provide space object cataloging and identification , satellite attack warning , timely notification to U . S . forces of satellite fly - over , space treaty monitoring , and scientific and technical intelligence gathering . The continued increase in satellite and orbital debris populations , as well as the increasing diversity in launch trajectories , non - standard orbits , and geosynchronous altitudes , necessitates continued modernization of the SSN to meet existing and future requirements and ensure their cost - effective supportability . SPACETRACK also developed the systems interfaces necessary for the command and control , targeting , and damage assessment of a potential future U . S . anti - satellite weapon ( ASAT ) system . There is an Image Information Processing Center and Supercomputing facility at the Air Force Maui Optical Station ( AMOS ) . The resources and responsibility for the HAVE STARE Radar System development were transferred to SPACETRACK from an intelligence program per Congressional direction in FY93 . 1957 – 1963 . The first formalized effort to catalog satellites occurred at Project Space Track , later known as the National Space Surveillance Control Center ( NSSCC ) , located at Hanscom Field in Bedford , Massachusetts . The procedures used at the NSSCC were first reported in 1959 and 1960 by Wahl , who was the technical director of the NSSCC . In 1960 , under Project Space Track , Fitzpatrick and Findley developed detailed documentation of the procedures used at the NSSCC . For the early history of satellite tracking , 1957 – 1961 , see Project Space Track . Observation of satellites was performed at more than 150 individual sites . Contributions came from radar stations , Baker – Nunn camera s , telescopes , radio receivers , and the Operation Moonwatch participants . Individuals at these sites took observations on satellites by visual means . There were numerous observation types and sources . The observations were transferred to the NSSCC by teletype , telephone , mail , and personal messenger . There , a duty analyst reduced the data and determined corrections that should be made to the orbital elements before they were used for further prediction . After this analysis , these corrections were fed into an IBM 709 computer that computed the updated orbital data . These updated orbital data were then used in another phase of the same computer program to yield the geocentric ephemeris . From the geocentric ephemeris , three different products were computed and sent back to the observing stations for their planning of future observing opportunities . Missile Warning and Space Surveillance in the Eisenhower Years . The launch of Sputnik 1 triggered a need for tracking of objects in space using the Space Tracking System . The first US system , Minitrack , was already in existence at the time of the Sputnik launch , but the US quickly discovered that Minitrack could not reliably detect and track satellites . The US Navy designed Minitrack to track the Vanguard satellite , and so long as satellites followed the international agreement on satellite transmitting frequencies , Minitrack could track any satellite . However , the Soviets chose not to use the international satellite frequencies . Thus , a major limitation of this system became visible . Minitrack could not detect or track an uncooperative or passive satellite . Concurrent with Minitrack was the use of the Baker - Nunn satellite tracking cameras . These systems used modified Schmidt telescopes of great resolution to photograph and identify objects in space . The cameras first became operational in 1956 and eventually operated at sites worldwide . The Air Force ran five sites , the Royal Canadian Air Force ran two , and the Smithsonian Institution ' s Astrophysics Observatory operated a further eight sites . The Baker - Nunn system , like Minitrack , provided little real - time data and was limited to night , clear weather operations . Beyond the problems in acquiring data on satellites , it became obvious that the US tracking network would soon be overwhelmed by the tremendous number of satellites that followed Sputnik and Vanguard . The amount of satellite tracking data accumulated required creation or expansion of organizations and equipment to sift through and catalog the objects . The need for real - time detection and tracking information to deal with Soviet satellite launches led on 19 December 1958 to ARPA ' s implementation of Executive Order 50 - 59 to establish a spacetrack network . This spacetrack network , Project Shepherd , began with the Space Track Filter Center at Bedford , Massachusetts , and an operational space defense network ( i . e . , a missile warning network ) . ARDC took up the spacetrack mission in late 1959 and in April 1960 set up the Interim National Space Surveillance Control Center at Hanscom Field , Massachusetts , to coordinate observations and maintain satellite data . ( 96 ) At the same time , DOD designated the Aerospace Defense Command ( ADCOM ) , formerly Air Defense Command , as the prime user of spacetrack data . ADCOM formulated the first US plans for space surveillance . US Space Catalog . The United States Department of Defense ( DoD ) has maintained a database of satellite states since the launch of the first Sputnik in 1957 , known as the Space Object Catalog , or simply the Space Catalog . These satellite states are regularly updated with observations from the Space Surveillance Network , a globally distributed network of interferometer , radar and optical tracking systems . Two separate catalog databases are maintained under the USSTRATCOM : a primary catalog by the Air Force Space Command ( AFSPC ) , and an alternate catalog by the Naval Space Command ( NSC ) . By the year 2001 , the number of cataloged objects was nearly 20 , 000 . Different astrodynamics theories are used to maintain these catalogs . The General Perturbations ( GP ) theory provides a general analytical solution of the satellite equations of motion . The orbital elements and their associated partial derivative s are expressed as series expansion s in terms of the initial conditions of these differential equation s . The GP theories operated efficiently on the earliest electronic computing machines , and were therefore adopted as the primary theory for Space Catalog orbit determination . Assumptions must be made to simplify these analytical theories , such as truncation of the Earth ’ s gravitational potential to a few zonal harmonic terms . The atmosphere is usually modeled as a static , spherical density field that exponentially decays . Third body influence s and resonance effects are partially modeled . Increased accuracy of GP theory usually requires significant development efforts . NASA maintains civilian databases of GP orbital elements , also known as NASA or NORAD two - line elements . The GP element sets are " mean " element sets that have specific periodic features removed to enhance long - term prediction performance , and require special software to reconstruct the compressed trajectory . Shemya and Diyarbakir Radar Sites . AN / FPS - 17 and AN / FPS - 80 radars placed at Shemya in the 1960s to track Soviet missile tests and to support the Air Force Spacetrack System . In July 1973 , Raytheon won a contract to build a system called " Cobra Dane " on Shemya Island in the Aleutian Islands off the Alaskan coast . Designated as the AN / FPS - 108 , Cobra Dane replaced AN / FPS - 17 and AN / FPS - 80 radars . Becoming operational in 1977 , Cobra Dane also had a primary mission of monitoring Soviet tests of missiles launched from southwest Russia aimed at the Siberian Kamchatka peninsula . This large , single - faced , phased - array radar was the most powerful ever built . The FPS - 80 was a tracking radar and the FPS - 17 was a detection radar for Soviet missiles . Both were part of the Ballistic Missile Early Warning System ( BMEWS ) . The large detection radar ( AN / FPS - 17 ) went into operation in 1960 . In 1961 , the AN / FPS - 80 tracking radar was constructed nearby . These radars were closed in the 1970s . The Pirinclik ( near Diyarbakir , Turkey ) intelligence collection radar consisted of one detection radar and one tracking radar . The Pirinclik radar was operated by the 19th Surveillance Squadron . The radar reached IOC on 1 June 1955 . The Pirinclik Radar Site consisted of a detection radar ( AN / FPS - 17 ) and a mechanical tracking radar ( AN / FPS - 79 ) . Both radars operated at a UHF ( 432 MHz ) frequency . Although limited by their mechanical technology , Pirinclik ' s two radars give the advantage of tracking two objects simultaneously in real time . Its location close to the southern Former Soviet Union makes it the only ground sensor capable of tracking actual deorbits of Russian space objects . In addition , the Pirinclik radar was the only 24 - hour - per - day eastern hemisphere deep space sensor . Radar operations at Pirinclik were terminated in March 1997 . AN / FPS - 17 . With the Soviet Union apparently making rapid progress in its rocket program , in 1954 the United States began a program to develop a long range surveillance radar . General Electric Heavy Military Electronics Division ( HMED ) in Syracuse , NY was the prime contractor and Lincoln Laboratory was a subcontractor . This tracking radar , the AN / FPS - 17 , was conceived , designed , built , and installed for operation in nine months . The first installation , designated AN / FPS - 17 ( XW - 1 ) was at Diyarbakir ( Pirinclik ) , Turkey , to detect Soviet launches . A second system , designated AN / FPS - 17 ( XW - 2 ) , was installed at Laredo AFS ( about northeast of Laredo AFB ) in Texas , to track rockets launched from White Sands , New Mexico , and serve as a radar test bed . A third system , designated AN / FPS - 17 ( XW - 3 ) , was installed on Shemya Island , Alaska , to detect Soviet launches . The Diyarbakir FPS - 17 became operational in June 1955 , the Laredo installation in February 1956 , and Shemya in May 1960 . The first two installations closed without replacements ; the Shemya installation was replaced by the Cobra Dane ( AN / FPS - 108 ) radar . The FPS - 17 antenna featured a fixed parabolic torus section reflector that typically stood high and wide and was illuminated by an array of radar feed horns placed in front of it . The transmitters operated in the VHF band , sending out pulses at frequencies between approximately 180 to 220 MHz . The FPS - 17 was unique in that , unlike most radar types , each site ’ s version differed from the other sites . Differences included transmitter equipment , reflector size and number , and the number and arrangement of feed horns . Additionally , the FPS - 17 was the first operational radar system to employ pulse compression techniques . There were two AN / FPS - 17 antennas at Diyarbakir , Turkey , one antenna at Laredo , and three at Shemya in the Aleutians . AN / FPS - 79 . The FPS - 79 at Diyarbakir had a unique feature which enhanced its Spacetrack usefulness . A variable - focus feed horn provided a wide beam for detection and a narrow beamwidth for tracking . Pulse compression was used to improve both the gain and resolution of the dish antenna . Steering was mechanical ; the FPS - 79 had a range of . The radar site closed in 1997 . After circling the Earth in an apparently dormant state for 9 months , on November 13 , 1986 the SPOT 1 Ariane third stage violently separated into some 465 detectable fragments - the most severe satellite breakup yet recorded prior to 2007 . Although the debris cloud did not pass over the continental United States until more than 8 hours later , personnel in the Space Surveillance Center ( SSC ) at the Cheyenne Mountain Complex in Colorado Springs , Colorado reported that the U . S . FPS - 79 radar at Pirinclik , Turkey , noticed the debris within minutes of the fragmentation . Blue Nine and Blue Fox . Blue Nine refers to a project which produced the AN / FPS - 79 Tracking Radar Set built by General Electric , used with the 466L Electromagnetic Intelligence System ( ELINT ) ; US Air Force . Blue Fox refers to a modification of the AN / FPS - 80 tracking radar to the AN / FPS - 80 ( M ) configuration . Shemya , AK , 1964 . Both of these systems incorporated GE M236 computers . AN / FPS - 80 . Built by General Electric . Used as tracker radar for Spacetrack network measurements once target detected . One sited at Sheyma . Principally used for intelligence purposes to track Russian missiles . Space Surveillance Network . The command accomplishes these tasks through its Space Surveillance Network ( SSN ) of U . S . Army , Navy and Air Force operated , ground - based radars and optical sensors at 25 sites worldwide . The SSN has been tracking space objects since 1957 when the Soviet Union opened the space age with the launch of Sputnik I . Since then , the SSN has tracked more than 24 , 500 space objects orbiting Earth . Of that number , the SSN currently tracks more than 8 , 000 orbiting objects . The rest have re - entered Earth ' s turbulent atmosphere and disintegrated , or survived re - entry and impacted the Earth . The space objects now orbiting Earth range from satellites weighing several tons to pieces of spent rocket bodies weighing only 10 pounds ( 4 . 5 kg ) . About seven percent of the space objects are operational satellites , the rest are debris . The USSTRATCOM is primarily interested in the active satellites , but also tracks space debris . The SSN tracks space objects which are 10 centimeters in diameter ( baseball size ) or larger . Space Surveillance Telescope program . The Space Surveillance Telescope program " ' ( SST ) " is DARPA ' s ground based , advanced , optical system for detection and tracking of faint objects in space such as asteroid s . It is also to be employed for space defense missions . The program is designed to advance , or expand , space situational awareness , and be able to quickly provide wide area search capability . Overview . The large curved focal surface array sensors are considered to be an innovative design . It encompasses improvements in detection sensitivity , has short focal length , wide field of view , and improvements in step - and - settle abilities . SST detects , tracks , and can discern small , obscure objects , in deep space with a " wide field of view system " . It is a single telescope with the dual abilities . First the telescope is sensitive enough to allow for detection , also , of small , dimly lit objects ( low reflectivity ) . Second it is capable of quickly searching the visible sky . This combination is a difficult achievement in a single telescope design . It is an F / 1 . 0 aperture telescope with a 3 . 5 meter primary mirror . It contains a curved , focal plane array . Multiple searches can be conducted from the ground multiple times throughout the night . As a telescope system , it can give precise locations of discovered objects , extrapolate the course of the object , and indicate the objects stability . The US Air Force will ultimately take over the program , and integrate the SST as a sensor in the Space Surveillance Network of the Air Force Space Command in FY 2009 . Air Force Space Surveillance System . The Air Force Space Surveillance System ( AFSSS ) , also known as the " space fence " , is a very high frequency radar network located at sites across the southern United States ( from California to Georgia ) with a centralized data processing site at the Naval Network and Space Operations Command in Dahlgren , Virginia . The " fence " is now operated by the U . S . Air Force ( 20th Space Control Squadron Detachment 1 ) . The Satellite Detection and Reconnaissance Defense ( the former designation of the NSSS ) reached initial operating capability in 1961 . Since then , the role of the " fence " has grown . The system detects space objects from new launches , maneuvers of existing objects , breakups of existing objects , and provides data to users from its catalog of space objects . Orbital parameters of more than 10 , 000 objects are maintained in this catalog — which has now gained usage by NASA , weather agencies , and friendly foreign agencies . The information is essential to computing the collision avoidance information to de - conflict launch window s with known orbiting space objects . Ground - based Electro - Optical Deep Space Surveillance . Ground - based Electro - Optical Deep Space Surveillance , or GEODSS , is an optical system that uses telescopes , low - light level TV cameras , and computers . It replaced an older system of six 20 inch ( half meter ) Baker - Nunn cameras using photographic film . There are three operational GEODSS sites that report to the 21st Operations Group : A site at Choe Jong San , South Korea was closed in 1993 due to nearby smog from the town , weather and cost concerns . Originally , the fifth GEODSS was planned to be operated from a site in Portugal , but this was never built . A mobile telescope that contributes to the GEODSS system is located at Morón Air Base , Spain GEODSS tracks objects in deep space , or from about 3 , 000 mi ( 4 , 800 km ) out to beyond geosynchronous altitudes . GEODSS requires nighttime and clear weather tracking because of the inherent limitations of an optical system . Each site has three telescopes . The telescopes have a 40 - inch ( 1 . 02 m ) aperture and a two - degree field of view . The telescopes are able to " see " objects 10 , 000 times dimmer than the human eye can detect . This sensitivity , and sky background during daytime that masks satellites reflected light , dictates that the system operate at night . As with any ground - based optical system , cloud cover and local weather conditions directly influence its effectiveness . GEODSS system can track objects as small as a basketball more than 20 , 000 miles ( 30 , 000 km ) in space or a chair at , and is a vital part of USSTRATCOM ’ s Space Surveillance Network . Distant Molniya orbiting satellites are often detected in elliptical orbits that surpass the Moon and back ( 245 , 000 miles out ) . Each GEODSS site tracks approximately 3 , 000 objects per night out of 9 , 900 object that are regularly tracked and accounted for . Objects crossing the International Space Station ( ISS ) orbit within will cause the ISS to adjust their orbit to avoid collision . The oldest object tracked is Object # 4 ( Vanguard 1 ) launched in 1958 . Space Based Visible ( SBV ) Sensor . The SSN included one spaceborne sensor , the space - based visible ( SBV ) sensor , carried into orbit aboard the Midcourse Space Experiment ( MSX ) satellite launched by the Ballistic Missile Defense Organization in 1996 . It was retired from service on June 2 , 2008 . The Space Based Space Surveillance ( SBSS ) pathfinder satellite now performs the mission previously handled by the MSX SBV .