Tiny pieces of space junk only 2 inches (5 centimeters) in size are cluttering a valuable orbital region where some of the costliest satellites reside, a new study has found.
Researchers from the University of Warwick in the U.K. found that the geostationary orbit — a region of space at the altitude of 22,000 miles (36,000 kilometers) — is full of dangerous, previously unseen bits of space junk that could destroy satellites.
The geostationary orbit is quite unique. Satellites at this altitude circle Earth in sync with the planet's rotation, appearing permanently suspended above a fixed spot on the equator. A single satellite in the geostationary ring has a constant view of a vast portion of the globe. This feature has been taken advantage of for decades for things like TV broadcasting, internet delivery, Earth observation and weather monitoring. But, as it appears, those satellites might not be safe up there at all.
"The debris in geosynchronous orbit is a potential minefield," Stuart Eves, the study’s co-author and space consultant at SJE Space, said in a statement. "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."
The researchers uncovered the previously invisible debris by re-examining a dataset from an earlier space debris survey conducted by astronomers using the 8.3-foot (2.54-meter) Isaac Newton Telescope in La Palma, Canary Islands. They ran the data through new image processing algorithms to distinguish smaller and much fainter fragments than was previously possible in the distant geostationary orbit.
"The blind stacking technique is a very powerful method for improving the sensitivity limit of astronomical datasets," Ben Cooke, a research fellow at the University of Warwick's Center for Space Domain Awareness and co-author of the paper, said in the statement. "It involves testing many potential paths in an image sequence along which hidden targets might be moving and stacking the images to help bring those targets above the noise floor. This project shows a successful, real-world application of the method."
The researchers found 25 previously missed debris tracks in the images, 80% of which were caused by previously unknown objects.
The finding is concerning as space debris at such high altitudes behaves differently from that circling closer to Earth. The residual atmosphere at 22,000 miles is almost non-existent, meaning there is no air drag to force the orbital clutter spiral into the atmosphere and burn up.
"Debris in the neighborhood of the geostationary belt is particularly concerning," James Blake, also a Warwick research fellow and the study’s co-author, said in the statement. "It's very far away, well above the Earth's atmosphere, so small objects tend to be incredibly faint and difficult to detect, and any debris that's generated will stick around indefinitely."
While orbits near Earth naturally clear up as the residual air at these altitudes slows the junk fragments down, at the higher altitude, the concentrations of such fragments will forever keep rising, making the region ever more tricky to operate in.
Moreover, the satellites that reside in this unique orbital region tend to be very large and expensive, designed for much longer missions than those making up megaconstellations in low Earth orbit. These satellites, frequently fitted with solar panels spanning 100 feet (30 meters) or more, can suffer substantial damage from a collision with the tiniest piece of junk.
"Pieces of space junk can be moving very quickly relative to one another, as much as several kilometers every second," Blake said. "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."
The researchers are now looking to analyze additional images obtained by other telescopes around the world to get a fuller understanding of the scale of the debris contamination in the region.
The study was published in the Journal of Astronautical Sciences in June.
