An American startup, Reflect Orbitalannounced a bold plan: to make a constellation of satellites capable of reflecting sunlight back to Earththus ensuring “sunlight on request” even after sunset.
The stated objective is to illuminate solar parks during the night hours, allowing them to continue generating electricity.
The project will begin with the launch of the first test satellite, Earendil-1a prototype equipped with a mirror 18 meters in diameter, scheduled for 2026. By 2030the company aims to put into orbit approximately 4,000 satellitesaccording to the most recent plans.
Unlike conventional satellites, which reflect sunlight accidentally and cause unintentional light pollutionthose of Reflect Orbital would be designed specifically to generate light. And this is precisely what worries astronomers around the world.
Reflect sunlight from space
The idea is based on a simple principle: reflect the Sun’s light back to the Earth through large orbiting mirrors. As happens when you orient the dial of a watch to reflect a beam of light, these satellites would focus the light on specific areas of the planet. However, the distances involved radically change the rules.
Reflect Orbital’s satellites would orbit at approx 625 kilometers altitudewith mirrors of 54 meters in diameter.But at such a distance, the reflected light would spread over a very large area – approx 7 kilometers in diameter – thus becoming less intense. In terms of brightness, a single satellite would produce one light 15,000 times weaker than direct sunlightbut anyway much more intense than the full moon.
A preliminary test conducted by the founder Ben Nowack using a hot air balloon he showed encouraging results: a mirror measuring 2.5 meters on a side he managed to generate 516 watts per square meter on solar panels 242 meters away, about half the solar output at midday.
However, scaling this experiment into space would be impracticable: to obtain similar results from 800 km away, a reflector of over 6.5 km per side – an area of 42 square kilometers.
Reflect Orbital, aware of these limitations, aims more modestly to achieve 200 watts per square meterthat is, about the 20% of daylight sunlight.
But even in this case the difficulties remain enormous: to obtain a similar light intensity, they would be necessary approximately 3,000 satellites to illuminate a single area.
Furthermore, a satellite in low orbit travels at 7.5 km per secondremaining visible over a given area for no more than 3.5 minutes. This means that, to guarantee one hour of continuous artificial light, it would be necessary tens of thousands of satellitesin constant motion and perfectly synchronized.
According to some of Nowack’s statements, the final plan would even include 250,000 satellitesa number higher than that of all objects currently tracked in spaceincluding orbital debris.
And even with such a fleet, the light provided would cover , provided the sky is clear.
Between ambition and danger
The question is inevitable: Can artificial sunlight really work? From a technical point of view, the answer seems negative. But the environmental and astronomical risks are much more concrete.
According to experts, even a single test satellite could shine brighter than the full mooncreating significant visual disturbances. An entire constellation, however, would transform the night sky into a mosaic of bright flashesdestroying astronomical visibility and putting it at risk visual health of someone who observes with a telescope.
Astronomers fear that such reflections, if directed at their instruments, could be almost as intense as direct sunlightwith the risk of permanent damage to vision And devastating interference with scientific observations. Furthermore, artificial light pollution would also have effects on nocturnal faunaalready strongly affected by changes in natural lighting.
Reflect Orbital, consulted by The Conversationdid not respond within the deadline, but declared a Bloomberg of wanting to maintain reflexes “short, predictable and targeted”avoiding astronomical observatories and communicating the position of satellites in advance.
However, many scientists remain skeptical. Even if the project were to take off, the risk of transform the night sky into a giant light screen it is very tall. And the consequences, for astronomy and for the beauty of the starry sky, could be irreversible.
