page_title: United States Space Surveillance Network
section_title: Ground-based Electro-Optical Deep Space Surveillance
hierarchical_section_title: United States Space Surveillance Network / Ground-based Electro-Optical Deep Space Surveillance
caption_attribution_description: AN/FSQ-114 Ground-Based Electro-Optical Deep Space Surveillance (GEODSS) Unit location: Det. 3, 21st Operations Group, Maui, Hawaii. Mission: Space surveillance — to detect, track and identify more than 2,500 objects in deep-space orbits. Provides photometric space object identification. Aperture opening: 40 inches Range: 3,000 miles to greater than 22,000 miles.
context_page_description: The United States Space Surveillance Network 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 the Joint Functional Component Command for Space, part of the United States Space Force.
  Space surveillance accomplishes the following:
  Predict when and where a decaying space object will re-enter the Earth's atmosphere;
  Prevent a returning space object, which to radar looks like a missile, from triggering a false alarm in missile-attack warning sensors of the U.S. and other countries;
  Chart the present position of space objects and plot their anticipated orbital paths;
  Detect new artificial objects in space;
  Correctly map objects travelling in the Earth's orbit;
  Produce a running catalog of artificial space objects;
  Determine ownership of a re-entering space object;
  Inform NASA whether or not objects may interfere with the International Space Station or satellite orbits.
  The SPACETRACK program represents a worldwide Space Surveillance Network of dedicated, collateral, and contributing electro-optical, passive radio frequency and radar sensors.
context_section_description: 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 which used photographic film.
  There are three operational GEODSS sites that report to the 21st Operations Group:
  Socorro, New Mexico 33.8172°N 106.6599°W
  AMOS, Maui, Hawaii 20.7088°N 156.2578°W
  Diego Garcia, British Indian Ocean Territory 7.41173°S 72.45222°E.
  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.
  Moron Optical Space Surveillance (MOSS), a transportable 22-inch aperture telescope that contributed to the GEODSS system was operational at Morón Air Base, Spain
  37.170°N 5.609°W from 1997 to 2012.
  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 35,000 miles (56,000 km), and is a vital part of USSPACECOM'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 20 miles (32 km) will cause the ISS to adjust their orbit to avoid collision. The oldest object tracked is Object #4 (Vanguard 1) launched in 1958.
caption: GEODSS atop the Haleakala crater
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