existing objects, breakups of existing objects, and provided data to users from its catalog of space objects. Orbital parameters of more than 10,000 objects were 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 windows with known orbiting space objects. The 21st Space Wing closed the Air Force Space Surveillance System on 1 October 2013 citing resource constraints caused by sequestration. A new S-band Space Fence is under construction at Kwajalein Atoll. 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. 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 derivatives are expressed as series expansions in terms of the initial conditions of these differential equations. 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 influences 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 were placed at Shemya Island in the Aleutian Islands off the Alaskan coast 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. Designated as the AN/FPS-108, Cobra Dane replaced AN/FPS-17 and