The JSpOC maintains the catalog of all artificial Earth-orbiting objects, charts preset positions for orbital flight safety, and predicts objects reentering the Earth's atmosphere. Since the launch of Sputnik in 1957, over 39,000 man-made objects have been catalogued, many of which have since re-entered the atmosphere. Currently, the JSpOC tracks more than 16,000 objects orbiting Earth. About 5 percent of those being tracked are functioning payloads or satellites, 8 percent are rocket bodies, and about 87 percent are debris and/or inactive satellites.
JSpOC tasks the Space Surveillance Network (SSN), a worldwide network of 30 space surveillance sensors (radar and optical telescopes, both military and civilian) to observe the objects. The crews match sensor observations to the orbiting objects, catalog, and update the position and velocity of each one. These updates form the Satellite Catalog, a comprehensive listing of the numbers, types, and orbits of all trackable objects in space.
The JSpOC uses the SSN to take between 380,000 to 420,000 observations each day.