Researchers have warned that plans to install reflective mirrors in space and up to a million more satellites into low Earth orbit could have “far-reaching” consequences for human health and ecosystems.
Presidents of four international scientific societies representing about 2,500 researchers from more than 30 countries are among those who have raised concerns in letters to the US Federal Communications Commission (FCC), The Guardian newspaper has reported.
The FCC is considering plans by a start-up called Reflect Orbital to illuminate parts of the Earth at night using reflective satellites, as well as applications from SpaceX that could dramatically expand satellite numbers in low Earth orbit.
“The proposed scale of orbital deployment would represent a significant alteration of the natural night-time light environment at a planetary scale,” said the presidents of the European Biological Rhythms Society (EBRS), the Society for Research on Biological Rhythms, the Japanese Society for Chronobiology and the Canadian Society for Chronobiology.
They said altering the light-dark cycle could disrupt biological clocks that regulate sleep and hormone secretion in humans and animals, migration in nocturnal species, seasonal cycles in plants and the rhythms of marine phytoplankton that underpin ocean food webs.
They have urged regulators to conduct a full environmental review and set limits on satellite reflectivity and cumulative night sky brightness.
Reflect Orbital hopes to use satellites equipped with large reflective mirrors to redirect sunlight on to areas roughly 5km to 6km wide “on demand”, with brightness adjustable “from full moon to full noon”, the newspaper said.
The company says the system could extend solar energy production into the evening and provide lighting for construction projects, disaster response and agriculture, with illumination delivered only to locations approved by local authorities.
Meanwhile, SpaceX has proposed launching up to one million satellites to create a giant solar-powered computing network in orbit designed to run artificial-intelligence workloads. The company says the system could reduce the energy and cooling demands of terrestrial datacentres.
DarkSky International has also written to the FCC. Its chief executive Ruskin Hartley said: “While ideas like mirrors on satellites beaming ‘sunlight on demand’ to Earth or mega-constellations of up to 1m satellites for AI datacentres may sound like science fiction, these proposals are very real.”
He added: “Scientific studies have already shown that the existing number of satellites in orbit has increased diffuse night sky brightness, or sky glow, by roughly 10%.”
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