Astronomers are concerned with the precedent set by BlueWalker 3, a recently launched communications satellite that has become one of the brightest objects in the night sky.

A committee from the International Astronomical Union (IAU) said the satellite and potential successors are a danger to ground-based and radio astronomy. Observations coordinated by the IAU found BlueWalker3 is brighter than other constellation satellites and could be as bright as the most recognizable stars.

“The growing encroachment of artificial sky glow from urban areas has already had a dramatic effect on humanity’s intimate connection to the night sky,” said NOIRLab Director Patrick McCarthy in a statement. “The addition of large numbers of bright artificial satellites further limits our ability to conduct research in astronomy and is a cause of alarm for people around the globe.”

BlueWalker 3 was developed by Texas-based AST SpaceMobile and launched into low Earth orbit in September 2021. The experimental satellite is designed to support a space-based cellular broadband network with a 64 square-metres array. 

After fully unfurling in early November, BlueWalker 3 became larger than any other commercial antenna system ever sent into low Earth orbit. The company plans to build a network of at least 168 satellites it calls BlueBirds.

SpaceX’s Starling satellites have already wreaked havoc with many ground-based observers. BlueWalker’s reflective surface goes one step further by emitting strong radio waves that could hurt radio astronomy as well.

The IAU supports developing this technology, but said governments and the commercial sector should design future satellites with minimal impacts on astronomy. The group also argues the night sky should be treated as “an important part of humanity’s shared cultural heritage.”

“BlueWalker 3 is a big shift in the constellation satellite issue and should give us all reason to pause,” said Piero Benvenuti, a director with the IAU, in a statement.