Astronomers are becoming increasingly concerned about light pollution in the night sky caused by the growing number of satellites, and also space junk, in low-Earth orbit.
Sunlight reflecting off the surfaces of the satellites and junk negatively impacts the astronomers’ work as it interferes with their ability to get a clear view of the night sky. The light from the satellites can appear as streaks across images of space, or might be so bright that it prevents fainter objects from being observed.
In a series of papers published in Nature this week, astronomers highlighted how the situation is set to deteriorate further unless regulations are put in place to reduce the number of launches that put small satellites into low-Earth orbit.
Astronomers’ concerns about light pollution became more prominent when SpaceX began regular launches of multiple satellites for its internet-from-space Starlink service in 2019. SpaceX now has more than 3,000 Starlink satellites orbiting Earth, but it could deploy as many as 42,000 satellites in the coming years.
Amazon also has plans for a similar space-based internet service with Project Kuiper and is set to launch more than 3,000 satellites in the next decade.
Responding to astronomers’ concerns, SpaceX tried to reduce the brightness of the reflections on its satellites by adding visors to them. But in one of the Nature papers, astronomers explained that that solution isn’t particularly effective as optically darker objects often radiate more brightly in infrared and submillimeter wavelengths, thereby causing interference with ground-based observations at those wavelengths.
Astronomers are also concerned that deploying more satellites in low-Earth orbit increases the risk of collisions that will create even more light-reflecting space junk.
They said that the issue could have “profound consequences” for Earth-based astronomy projects, with the light ruining images and preventing astronomers from spotting fainter objects in the night sky.
“Despite a narrative of democratizing space and delivering affordable global broadband, it is a model that prioritizes urgency, privatized benefits, and short-term goals over real sustainability and the public interest,” the authors of one of the papers said. “This also ignores our shared ancestry and heritage in space.”
Another of the research papers commented: “The recently agreed UN High Seas Treaty to protect international waters should give us hope that the skies can be similarly protected. Events such as the recent appearance of the Aurora Borealis across the U.K. and down to southern England in late February remind people to look up and be amazed. We should capitalize on the excitement and preserve such wonders for future generations.”
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