The night sky is about to get a lot brighter, and not in a good way. Scientists are warning of a potential disaster for both human health and the natural world as a result of plans to deploy reflective mirrors and up to a million more satellites in low Earth orbit. These proposals, if approved, could have far-reaching consequences for our sleep, ecosystems, and even food security.
The concern comes from the presidents of four international scientific societies representing around 2,500 researchers from over 30 countries. They have written to the US Federal Communications Commission (FCC) to express their worries about the potential impact of these satellite deployments.
One of the main issues is the disruption of biological clocks. Altering the natural light-dark cycle could affect sleep and hormone secretion in humans and animals, migration patterns in nocturnal species, seasonal cycles in plants, and the rhythms of marine phytoplankton that form the base of ocean food webs. This could have a cascading effect on entire ecosystems.
The scientists are calling for a full environmental review and the setting of limits on satellite reflectivity and night sky brightness. They argue that the proposed scale of orbital deployment would significantly change the natural night-time light environment, and this could have global implications.
One company, Reflect Orbital, aims to use satellites with large reflective mirrors to redirect sunlight onto specific areas, adjusting brightness from a full moon to full noon. While this could provide benefits like extended solar energy production and lighting for various industries, it also raises concerns about light pollution and public safety.
Another proposal from SpaceX involves launching up to a million satellites to create a giant solar-powered computing network in orbit. This system is designed to run artificial-intelligence workloads and reduce energy demands on terrestrial data centers. However, the potential impact on the night sky and biological systems is a major worry.
Ruskin Hartley, from DarkSky International, emphasizes that these proposals are very real and already have observable effects. Scientific studies have shown that the existing number of satellites has increased diffuse night sky brightness by around 10%. This additional brightness, while not as intense as moonlight, is significant and will continue to grow if current trends persist.
Dr Miroslav Kocifaj supports this view, predicting that night sky brightness will increase substantially by 2035, approaching the threshold set by astronomers for preserving naturally dark skies. The concern is that this brightness will be global and unavoidable, even in remote locations.
Prof Tami Martino highlights the sensitivity of biological systems to light levels, suggesting that the real question is not the brightness compared to moonlight but whether these systems can detect the change. Circadian disruption, according to the World Sleep Society and other organizations, is not just an inconvenience but a physiological mechanism linked to major health consequences.
As satellite numbers grow, the night sky could become dominated by artificial objects, potentially outnumbering visible stars. This would significantly alter the human experience of the night sky and affect the navigation of many birds and insects. The introduction of new forms of light pollution, including intense glare and blinding flashes, is also a concern that needs careful study.
In conclusion, the plans to deploy reflective mirrors and a million satellites in low Earth orbit are a cause for serious concern. The potential disruption to biological clocks and ecosystems, as well as the introduction of new forms of light pollution, could have profound and far-reaching consequences. Regulators and policymakers need to carefully consider these warnings and take appropriate action to protect our natural world and human health.
