Sun. Dec 3rd, 2023
The Brightness of Communications Satellites Threatens Astronomical Observation

One of the brightest objects in the night sky is not a natural celestial body, but a communications satellite. The BlueWalker 3 satellite, launched in September 2022, has become the eighth-brightest object in the sky. This prototype is part of a larger constellation of broadband communications satellites called BlueBird, which is expected to be launched next year.

The brightness of BlueWalker 3 is attributed to its 692-square-foot array of solar panels that reflects a significant amount of sunlight. Researchers from the University of Atacama, led by astronomer Sangeetha Nandakumar, have recently tracked the satellite to measure its brightness. Their findings, published in the journal Nature, raise concerns for those who value stargazing.

AST SpaceMobile, the satellite designer, plans to launch the first five BlueBird satellites in early 2024, followed by an additional 20 satellites later that year. If no significant changes are made to the satellite design, this could result in the presence of 25 objects brighter than most stars in the night sky.

The increasing trend of larger and brighter satellites continues, with Amazon planning to launch 3,200 broadband satellites for its Project Kuiper constellation and SpaceX’s StarLink constellation already having over 5,000 satellites in orbit. These satellite constellations pose a challenge for astronomers, hindering their ability to observe space from Earth. Not only does the brightness of these satellites complicate visibility, but radio signals and infrared emissions from them can also disrupt astronomical studies.

Attempts have been made to mitigate satellite brightness, such as StarLink’s experimentation with dark coatings that reduce the brightness by approximately 50%. It is crucial to assess the potential impact on the night sky before satellite launches are approved by the Federal Aviation Administration.

Additionally, light pollution on Earth is causing the night sky to become approximately 10% brighter each year. A study published in January suggests that in a generation or two, people may no longer be able to see stars in the night sky, only a brightly lit void.