Some of the faintest pieces of space junk ever seen in geosynchronous orbit turned up in old telescope photos. Researchers led by the University of Warwick found 25 faint objects roughly 36,000 kilometers (22,400 miles) above Earth’s equator, and close to 80 percent of them were missing from public debris catalogs.
The results appeared in the Journal of the Astronautical Sciences. Some scientists describe the hidden population as a “potential minefield” for the satellites that sit in that orbit.
Old images, new method
The team did not need fresh observations. They went back through archival images taken with the 2.54-meter Isaac Newton Telescope in the Canary Islands and applied a technique called “blind stacking,” together with advanced image-processing algorithms. That let them pick out fragments as small as five centimeters. The detections are among the faintest debris ever recorded in the orbit.
Brightness measurements added another finding. Variations in the light the objects reflect showed that many of them are tumbling.
Because atmospheric drag at that altitude is essentially nonexistent, debris there could stay in orbit for centuries.
Why size does not settle it
Geosynchronous orbit is where satellites for communications, television broadcasting, weather forecasting and environmental monitoring operate. Objects there stay in step with the planet’s rotation, which is why the orbit is considered some of the most valuable space around Earth.
Dr. James Blake of Warwick’s Centre for Space Domain Awareness, the study’s lead author, said relative speeds can reach several kilometers every second. “The energies involved are really high, and even small debris can cause a lot of damage to very expensive satellites, so small things really matter,” he said.
Co-author Dr. Stuart Eves of SJE Space Ltd. was blunter. “The debris in the neighborhood of the geostationary belt is a potential minefield,” he said. “No one in their right mind would enter a terrestrial minefield without a mine detector. Similarly, no one in their right mind should launch a satellite to GEO without an adequate debris survey.”
There is a more hopeful reading. The same work shows researchers can now find debris this small if they know how to look.
The project reached beyond Europe, with collaborators in Australia and Japan, and the team says international cooperation will be needed to track dangerous debris as more satellites go up. Blake pointed to the limited room in the belt. “There are a finite number of orbital slots in the GEO belt, so it’s important that we know how much debris is out there, how it behaves, what risks are posed to the active satellites we rely on,” he said. “Surveys for faint debris help us build a clearer picture.”
The paper is titled “DebrisWatch II: Digging Deeper for Geosynchronous Debris.”
