How reflective satellites will harm ecosystems across the Earth
What's the story
Plans to deploy reflective satellites and mirrors in low Earth orbit have raised alarms among researchers. The proposed technology could disrupt human health and ecosystems globally, experts have warned. The presidents of four international scientific societies, representing some 2,500 researchers from over 30 countries, have raised concerns about these plans in letters to the US Federal Communications Commission (FCC).
Potential
Disruption to biological clocks and ecosystems
The proposed scale of orbital deployment would drastically alter the natural night-time light environment on a global scale. This change could disrupt biological clocks regulating sleep and hormone secretion in humans and animals, migration patterns of nocturnal species, seasonal cycles in plants, and even marine phytoplankton rhythms that underpin ocean food webs.
Call for caution
Potential implications for food security
The researchers have urged regulators to conduct a thorough environmental review and impose limits on satellite reflectivity and cumulative night sky brightness. Professor Charalambos Kyriacou, a geneticist at the University of Leicester, warned that these plans could have global implications for food security as plants require the night. Reflect Orbital plans to use satellites with large reflective mirrors to redirect sunlight onto areas about 5km-6km wide on demand.
Expansion proposal
SpaceX's mega constellation plan adds to concerns
Meanwhile, SpaceX has proposed launching up to one million satellites to create a massive solar-powered computing network in orbit. The company claims this system could cut down energy and cooling requirements of terrestrial data centers. However, these proposals have also drawn criticism from experts who warn about their potential impact on the night sky and ecosystems.
Current impact
Current satellites already brightening night sky
Ruskin Hartley, the CEO of DarkSky International, a non-profit dedicated to protecting natural night skies, emphasized that the current number of satellites in orbit has already increased diffuse night sky brightness/sky glow by about 10%. Dr. Miroslav Kocifaj from the Slovak Academy of Sciences in Bratislava noted that individual satellites might leave streaks in telescope images, while sunlight reflected by satellites and debris brightens the sky.
Future projections
Predicted rise in brightness by 2035
Kocifaj's modeling suggests such objects already add between 3-8 microcandela per square meter to night sky brightness. By 2035, he predicts this might rise to between 5-19 microcandela, nearing the threshold that astronomers have set for preserving naturally dark skies. Professor Tami Martino from the University of Guelph said that the real question is not brightness compared to moonlight, but whether biological systems can detect the change.