Light pollution from proposed satellites will likely hinder the ability to see celestial bodies at night and could impact biological clocks and ecosystems
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Current proposals to launch more than 1.7 million satellites into orbit – including extremely bright ones – would have ‘devastating consequences to astronomy’, a new study by the European Southern Observatory (ESO) has revealed.
Since 2019, the number of satellites orbiting Earth has increased rapidly. Today, more than 14,000 orbit Earth – most of which are part of SpaceX’s Starlink telecommunications fleet. While SpaceX and other companies have taken measures to make their satellites less bright, current satellite proposals are going ‘beyond the limit’ of what astronomy can withstand, says astronomer at ESO, Olivier Hainaut.
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According to the study, no more than 100,000 faint satellites below naked-eye visibility should orbit Earth in order to safeguard our ability to observe the night sky with telescopes.
Currently, SpaceX plan to send one million more satellites into orbit for space-based data centres – a decision that would significantly alter the appearance of the sky. The new study shows that hundreds of satellites would be visible for a large proportion of each night, while other planned satellite constellations such as E-Space’s Cinnamon and China’s CTC-1 and 2 would add hundreds of thousands more satellites into orbit.
A US start-up, Reflect Orbital, also plans to launch a constellation of mirror-like satellites to provide sunlight at night, aiming to increase its satellite population to 35,000 by 2035. These satellites would be the brightest ever in orbit, leading to harmful effects on Earth’s dark skies. If 50,000 of these satellites were put into space, the sky would be up to three to four times brighter overall.
From a light-polluted city like Munich in Germany, these satellites would appear as the only ‘stars’ visible in the night sky.
Overall, such proposals would brighten the night sky, hindering the ability to observe galaxies, Earth-like planets and even asteroids that are dangerous to Earth.
Light pollution from very bright satellites can also impact life on Earth, disrupting biological clocks and ecosystems. Large constellations of satellites have impacts beyond light pollution, with effects on air quality from the numerous launches required to send and maintain thousands of satellites.
‘Low Earth orbit is a celestial seashore that provides immense value to modern life, from global connectivity to our clear access to the Universe,’ concluded Hainaut.
‘However, we must manage the footprint of mega-constellations – from the light pollution affecting astronomy to the atmospheric effects of satellite re-entry – to ensure this resource remains pristine and accessible for future generations.’
