A Survey That Revealed a Gap
The Spacewatch project, founded in 1980 at the University of Arizona’s Lunar and Planetary Laboratory, normally uses its 0.9-meter telescope at Kitt Peak National Observatory in Arizona to survey near-Earth objects. Led by astronomer Vishnu Reddy, the team repurposed that instrument in 2022 to search for uncataloged debris in geosynchronous orbit. Over four nights, they observed a 1.8-degree-wide field near the equatorial plane. They detected 59 objects. Only 13 of those appeared in public catalogs.
The newly spotted debris ranged from 10 centimeters to 1 meter in size. Based on the survey, the study, published in the journal Acta Astronautica, estimated that the total number of debris objects larger than 10 centimeters in geosynchronous orbit could be two to three times higher than the roughly 8,000 objects tracked by the U.S. Space Force. The team used the telescope’s CCD camera and a custom algorithm to distinguish debris from stars. The study did not propose a solution; it simply demonstrated that an existing, relatively modest ground-based telescope — one built for asteroid science — can find debris that the official sensor network does not see.
Why Geosynchronous Orbit Matters
A geosynchronous orbit is an Earth-centered path whose period matches the planet’s rotation, so an object keeps a fixed or repeating position above the ground. The idea of such an orbit was described in 1929 by Herman Potočnik as useful for space stations. Arthur C. Clarke expanded the concept in a 1945 paper and proposed it for relay communications satellites. The first geosynchronous satellite was designed by Harold Rosen during his engineering work in the mid-twentieth century.
Today, communications satellites have long used geostationary and near-geostationary paths so ground antennas can stay aimed at one spot. That region has become a crowded belt of operational spacecraft. The concentration makes tracking gaps a standing concern for operators and regulators. Uncounted debris there raises collision exposure for the satellites that carry television, weather, and military links that readers rely on daily. A collision with a 10-centimeter fragment at orbital velocities would be catastrophic.
Limitations of Current Tracking
The U.S. Space Force’s Space Fence, a ground-based S-band radar on the Kwajalein Atoll that became operational in 2020, can detect objects as small as 5 centimeters in low Earth orbit. But it has limited sensitivity in geosynchronous orbit due to distance. The U.S. Space Surveillance Network, comprising more than 30 sensors worldwide, relies on optical telescopes for geosynchronous orbit. The European Space Agency’s Optical Ground Station in Tenerife, Spain, also conducts debris surveys there.
The study highlighted that many debris objects in geosynchronous orbit are in high-inclination orbits, making them harder to track. The U.S. Space Force tracks roughly 8,000 objects in that region; the Spacewatch data suggests the real number could be double or triple that. Uncounted debris means unquantified collision risk for operational satellites. The study did not offer a remedy, but it underscored that a modest ground-based instrument — one already in use for asteroid science — can expose a blind spot in humanity’s ability to monitor what is orbiting the planet.
