Since the launch of Sputnik on Oct. 4,
1957, the heavens have become increasingly crowded.
Today there are more than 8,000 known objects in orbit around the Earth. These objects range from active payloads, such as weather or communications satellites, to "space junk" such as launch vehicle debris and debris generated from satellite breakups.
The responsibility for keeping track of all man-made objects in orbit belongs to the U.S. Space Command Space Control Center, located within Cheyenne Mountain in Colorado Springs, Colo. The center receives orbital data from Ground-Based Electro-Optical Deep Space Surveillance (GEODSS) sites assigned to Air Force Space Command (AFSPC). GEODSS sites play a vital role in tracking these objects, particularly those in deep space. Over 2,500 objects, including geostationary communications satellites, are in deep space orbits more than 3,000 miles from earth.
There are three operational GEODSS sites that report to the 21st Space Wing, headquartered at Peterson AFB, Colo. Sites are located at Socorro, N.M.; Maui, Hawaii; and Diego Garcia, British Indian Ocean Territories.
The GEODSS system is the successor to the Baker-Nunn camera, which was developed in the mid-1950’s to provide surveillance data. The GEODSS concept was developed and researched by Massachusetts Institute of Technology Lincoln Laboratories at the Experimental Test Site located at Socorro, N.M. The ETS is still in use by MIT for research supporting the next generation of optical sensors.
To perform its mission, GEODSS brings together the telescope, low-light-level television cameras, and computers -- three proven technologies. Each site has three telescopes, two main and one auxiliary, with the exception of Diego Garcia, which has three main telescopes. The main telescopes have a 40-inch aperture and a two-degree field of view. The auxiliary telescopes have a 15" aperture and six-degree field of view. The telescopes are able to "see" objects 10,000 times dimmer than the human eye can detect. The system only operates at night. Since it is an optical system, cloud cover and local weather conditions influence its effectiveness.
The telescopes scan the sky at the same rate as the stars appear to move. This keeps the distant stars in the same positions in the field of view. As the telescopes slowly move, the GEODSS cameras take very rapid electronic snapshots of the field of view. Four computers then take these snapshots and overlay them on each other. Star images, which remain fixed, are electronically erased. Man-made space objects, however, do not remain fixed and their movements show up as tiny streaks which can be viewed on a console screen. Computers measure these streaks and use the data to figure the positions of objects such as satellites in orbits from 3,000 to 22,000 miles. This information is used to update the list of orbiting objects and sent nearly instantaneously from the sites to Cheyenne Mountain AFB.
The GEODSS system, which can track objects as small as a basketball more than 20,000 miles in space, is a vital part of Air Force Space Command.
(Current as of May 1997)
