This giant, next-generation satellite is now one of the brightest objects in the night sky

AST SpaceMobile’s BlueWalker 3 test satellite is 693 square feet in size. Image: AST Mobile via Business Wire

AST SpaceMobile’s BlueWalker 3 test satellite is 693 square feet in size.Image: AST Mobile via Business Wire

By Justine Calma,
Published by The Verge, 2 October 2023

The enormous, next-generation communications satellite BlueWalker 3 has become one of the brightest objects visible in the night sky, according to new research published today in the journal Nature.

While BlueWalker 3 is groundbreaking for its ability to essentially turn ordinary smartphones into satellite phones, it might also usher in a new generation of satellites that create way more light pollution than their older, smaller predecessors. Rapidly growing mega-constellations of internet satellites are already mucking up researchers’ observations of worlds beyond Earth. BlueWalker 3 is the brightest satellite in low Earth orbit yet, and astronomers fear it’s just the tip of the iceberg.

“If it does become an issue, then it’s going to completely change the night sky.”

“Let’s nip it in the bud now before it does become an issue. If it does become an issue, then it’s going to completely change the night sky,” says Jeremy Tregloan-Reed, one of the authors of the new Nature paper and an astronomer and assistant professor at the Universidad de Atacama in Chile.

BlueWalker 3 is about as bright as the eighth brightest star visible from Earth, Procyon, according to the new research. Only the Moon, Jupiter, Venus, and seven stars in our night sky are brighter than BlueWalker 3. That’s based on observations by professional and amateur astronomers from Chile, the US, Mexico, New Zealand, the Netherlands, and Morocco.

An image of the BlueWalker 3 satelliteMichael Tzukran

Typically, the larger the satellite, the brighter it is because there’s more surface area to reflect light. BlueWalker 3 is by far the brightest satellite in the sky because of its size, with a 64-square-meter (693 square feet) array. It’s the biggest commercial communications array in low Earth orbit, but it might not be for long since it’s only a prototype for a constellation of even larger satellites being developed by AST SpaceMobile and backed by AT&T.

Satellite trails can photobomb telescopic observations. Bright, star-like objects flying across the sky will make it more difficult to point out the constellations, Tregloan-Reed says. It also increases the sky background glow, which then makes it much harder to see nebulas, dust clouds, and finer details in the night sky.

A brighter night sky poses problems for wildlife, like birds who navigate by starlight. And over history, our view of the stars has also had incalculable cultural and spiritual value. But with light pollution growing at the rate it is now, a child born in a place where 250 stars are visible at night might only be able to see 100 by the time they’re 18 years old, previous research has found.

Earlier this year, BlueWalker 3 became the first satellite to successfully route an audio call between two unmodified smartphones without the need for cell towers. Working in a rural part of Chile, Tregloan-Reed says he understands the positive impact futuristic satellites like BlueWalker 3 can have on improving internet access and communication for many parts of the world that struggle with it now. He hopes that his work will spur the industry and consumers to support technologies that minimize light pollution. Companies might tweak their designs to reflect less light, for instance. And in the future, regulators might require an assessment of a satellite’s impact on the night sky as part of the authorization process before launch.

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