Satellites that provide us with essential weather reports, communication and navigation face a growing threat from space junk and other debris. Astronomers at the University of Warwick have found more than 75 percent of the debris they detected during a recent survey does not match any known objects in public satellite catalogues. The warning comes just two days after the International Space Station (ISS) narrowly avoided a collision with space debris for the third time this year.
NASA administrator Jim Bridenstine tweeted: “The @Space_Station has manoeuvred three times in 2020 to avoid debris.
“In the last two weeks, there have been three high concern potential conjunctions. Debris is getting worse!”
The Warwick astronomers are now calling for more efforts to survey the space around Earth for orbital hazards.
Their effort forms part of DebrisWatch, which is a collaboration between the university and the Defence Science and Technology Laboratory in the UK.
Space debris comes from a variety of sources: abandoned rocket stages, broken satellite parts or fragments from objects that have collided.
Even the smallest debris can be dangerous when travelling at hundreds or thousands of kilometres per second.
Lead author James Blake, a PhD student in the University of Warwick Department of Physics, said: “It’s important that we continue to observe the geosynchronous region with large telescopes wherever possible, to start to build up a more complete feel for the faint debris environment.
“With this survey, we’ve probed deeper than ever before, and still the population appears to be climbing as our sensitivity limit is reached.
“While we’re dealing with small number statistics here, it’s unsurprising that we see many more small, faint objects than large, bright ones.”
The astronomers surveyed the so-called geosynchronous region, which extends about 22,000 miles (36,000km) above Earth’s equator.
Satellites in geosynchronous orbits match the Earth’s rotation in perfect sync.
Debris is getting worse!
Jim Bridenstine, NASA administrator
And although satellites in orbit are spaced out in a way to avoid collisions, accidents still occur.
To detect the debris, the astronomers collected light over a large area using the 2.4m aperture Isaac Newton Telescope on the Canary Island of La Palma.
Sunlight bouncing off any object was then picked up by the telescope and analysed by custom computer software to create light curves of brightness over time.
The survey was optimised to track objects that are too small or too faint to be regularly monitored.
The astronomers found more than 75 percent of their detections – below and above one metre – did not match the publically available US Strategic Command (USSTRATCOM) database.
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Mr Blake said: “The light curves extracted from our survey images show just how varied these objects can be, both in terms of their physical nature and of their attitude or behaviour within orbit.
“Many of the faint, uncatalogued debris appear to be tumbling, showing significant brightness variation across the observation window.
“These sorts of features can tell us a lot about the perturbative forces acting on residents of the geosynchronous region, but also highlight that we need to be more careful when making assumptions about the properties of these objects.
“We need to probe the faint debris population further and obtain more data to gain a better understanding of what’s out there.”
Co-author Professor Don Pollacco, from the University of Warwick Department of Physics, said: “This kind of data will be key in the development of algorithms to characterise objects in the geosynchronous region.
“Remember that we’re not dealing with close-up photographs here, even the big satellites appear as non-resolved blobs of light in our images.
“Light curves offer a great opportunity to learn more about the way these objects behave and what they might be. The more high-quality data we take, the better chance we have of developing these tools.”
The survey’s results were published in the journal Advances in Space Research.
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