Light pollution from satellites: 'blackest black' as a possible remedy

A new study suggests that coating satellites with a material known as “Vantablack” could significantly reduce light pollution in space, potentially protecting astronomical observations. Researchers at the University of Surrey conducted simulations showing that this ultra-dark substance might bring satellite brightness close to the limit set by the International Astronomical Union to safeguard scientific research. The findings were published in the Monthly Notices of the Royal Astronomical Society. A team led by the researchers plans to test the idea using a small satellite called CubeSat Jovian 1, which will be coated with a lighter version of Vantablack named Vantablack 310. The issue of space-based light pollution has been growing rapidly over the past few years. As of 2023, more than 14,000 active satellites orbit Earth, with over two-thirds belonging to SpaceX’s Starlink constellation. In addition, nearly 20,000 inactive satellites and pieces of space debris already exist in orbit. Plans for future constellations could add up to 1.7 million more satellites. This surge threatens optical astronomy, with some experts calling it an “existential threat.” Earlier this month, the European Space Agency warned of the dangers posed by such developments. Vantablack is a material developed in Britain composed of carbon nanotubes that absorb 99.965 percent of incident light, making it appear pitch black. The research team simulated how a less intense variant, Vantablack 310, would affect satellite visibility. This version reflects approximately two percent of incoming light, with the rest diffused rather than reflected. As a result, satellites coated with Vantablack 310 would not create bright flashes visible from Earth. The researchers argue that this approach offers a scalable solution to combat light pollution without severely restricting space activities. However, the technique is not universally applicable. Satellites designed to reflect sunlight, often used for navigation or communication purposes, are unlikely to benefit from being coated with Vantablack. These satellites are frequently criticized for contributing to skyglow, and their function would remain unchanged under this method. Therefore, while the technology holds promise for certain types of satellites, its effectiveness depends on the specific design and purpose of each spacecraft. The problem of space-based light pollution has gained increasing attention among scientists and policymakers. The rise in satellite numbers has made the night sky increasingly crowded with artificial lights, affecting both professional and amateur astronomy. Some astronomers claim that the current level of light pollution could make traditional stargazing obsolete within a decade. The European Space Agency has expressed concern over these trends, urging greater regulation and awareness. Looking ahead, the research group hopes to demonstrate the practicality of using Vantablack 310 through the CubeSat Jovian 1 experiment. If successful, the method could offer a viable alternative to other mitigation strategies, such as limiting satellite operations during dark hours or adjusting their orbits. However, widespread adoption would require collaboration between satellite operators, regulatory bodies, and the scientific community. Until then, the debate over how best to balance technological progress with environmental and scientific concerns continues.