A Huge Satellite Is Now One of the Brightest Objects In the Sky, Astronomers Warn

The BlueWalker 3 satellite now out-shines all but the brightest stars and “could severely hamper progress in our understanding of the cosmos.”
A Huge Satellite Is Officially One of the Brightest Objects In the Sky, Astronomers Warn
Image: KPNO/NOIRLab/IAU/SKAO/NSF/AURA/R. Sparks

A huge new satellite, known as BlueWalker 3, has officially become one of the brightest objects in the sky—out-shining all but the brightest of stars—since it was launched into orbit by the space company AST SpaceMobile in September, astronomers say. 

The shiny glare of the 693-square-foot satellite, as well as its voluminous radio activity, “could severely hamper progress in our understanding of the cosmos,” according to a statement released on Monday by the International Astronomical Union. 

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Scientists involved with IAU’s Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS) also raised alarms about AST SpaceMobile’s plan to deploy a hundred satellites that are as big, or even larger, than BlueWalker 3 (BW3) in order to build a cellular broadband network designed to fill in coverage gaps around the world. 

The launch of BW3, which is the largest commercial communications array ever deployed in space, adds new urgency to the problem of severe light pollution and radio interference from the emerging satellite “megaconstellations” that have reached space in recent years for commercial purposes. The most obvious example is SpaceX’s Starlink, which already contains more than 3,000 satellites and may top 12,000 in the coming decade.

“Because of its large phased array antenna (64 square meters) BW3 appears in the sky as bright as some of the brighter stars,” said Piero Benvenuti, director of the IAU CPS, in an email to Motherboard. “If imaged by the very sensitive detectors of the astronomical telescopes, it can easily saturate them making the entire image useless and in some instances it might even damage the detector. It is therefore imperative to know exactly the position of such bright satellites in such a way they do not cross the field of view of the telescopes.” 

“Their impact on radio-astronomy is also potentially serious: large radio astronomical observatories are located in remote regions in order to limit the interference by the cellular phones: but if the microwave emission comes directly from the sky, no region on Earth will be immune from the interference,” he continued. 

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In addition to disrupting astronomical observations, these huge networks of spacecraft threaten the future of a pristine night sky which is “an important part of humanity’s shared cultural heritage and should be protected for society at large,” according to the IAU statement. Some experts have also called the constellations an example of “astrocolonialism” that has interfered with the traditional practices of Indigenous peoples around the world. 

Benvenuti noted that AST SpaceMobile has been discussing possible ways to mitigate the negative effects of their satellites with the IAU CPS. The IAU statement also acknowledged the positive effects of providing worldwide connectivity, but emphasized that these megaconstellations may come at the expense of our view of the sky, and all of the secrets it contains about our existence. 

“We know that there are several large constellations planned and currently being designed,” Benvenuti said. “The IAU CPS is actively trying to reach them to understand their potential impact both in terms of luminosity and radio interference.”

When asked to provide comment, AST SpaceMobile highlighted the benefits of its satellites to people on Earth, and said it is working to mitigate the effects on the night sky. 

“AST SpaceMobile's mission is to help solve the major global problem of lack of connectivity, which affects billions of people around the world,” the company said. “We are building the first and only space-based cellular broadband network—one that is designed to provide coverage to areas currently beyond the reach of today's networks.”

“We are eager to use the newest technologies and strategies to mitigate possible impacts to astronomy. We are actively working with industry experts on the latest innovations, including next-generation anti-reflective materials,” it continued. “We are also engaged with NASA and certain working groups within the astronomy community to participate in advanced industry solutions, including potential operational interventions.”

The company added that it intends to avoid broadcasts that are inside or nearby the National Radio Quiet Zone in the U.S.—a region designed to minimize radio interference around the iconic Green Bank radio observatory in West Virginia—as well as taking other measures to avoid an impact on radioastronomy worldwide. The statement also noted that AST SpaceMobile plans to deploy a constellation with 168 or fewer satellites, compared to other commercial constellations, like Starlink, that contain thousands of spacecraft.