Last November, a low-Earth orbit satellite was deployed in an expansive array spanning nearly 700 square feet, about the size of a studio.
Since then, the BlueWalker3 satellite has become one of the brightest objects in the sky, outshining some of the most radiant stars in the Milky Way, according to a study published on Monday in Nature, and it’s just the first of dozens of similar satellites being developed by AST SpaceMobile, a company that aims to keep smartphones connected from orbit.
Astronomers were already concerned about the emergence of satellite megaconstellations, like SpaceX’s Starlink, which have bright surfaces that sometimes interfere with views of space from Earth. The release and deployment of BlueWalker3 has compounded those concerns.
“The issue is not necessarily that satellite,” said Siegfried Eggl, an astrophysicist at the University of Illinois at Urbana-Champaign and an author of the new study, “but that it is a predecessor or prototype of a constellation, so there will eventually be many of them. those over there.”
Initially launched in September 2022, BlueWalker3 is the precursor to AST SpaceMobile’s BlueBird satellites, which aim to serve as a network of orbital cell towers with the goal of “democratizing access to knowledge and information regardless of where you live and people work,” an AST SpaceMobile spokesperson said. Last month, BlueWalker3 achieved broadcast its first 5G connection to a smartphone in a cellular coverage gap on Earth.
AST SpaceMobile is one of many companies competing to capture the growing demand for global broadband connectivity. SpaceX has launched about 5,000 satellites into space as part of its Starlink network, which already provides satellite Internet service. to customers worldwide. Other companies, such as Amazon (which is scheduled to will launch its first satellite prototypes on Friday) and OneWeb, have similar ambitions, and many countries are developing their own communications mega-constellations.
“Right now, we know there are 18 constellations planned around the world,” Dr. Eggl said. “The total number of satellites that people plan to install there is an impressive half a million. This is 100 times more than what we already have.”
The rapid proliferation of satellites in recent years has alarmed stargazers from all walks of life. As spacecraft move across the sky, they create bright trails and ambient glow in the sky that can destroy astronomical images and obscure fainter celestial objects that would otherwise be visible to the naked eye.
“There’s going to be a major change with these constellations,” said Jeremy Tregloan-Reed, an astronomer at the University of Atacama in Chile and author of the study.
AST SpaceMobile made the BlueWalker3 array so large that it could transmit strong cellular coverage directly to phones on Earth. The satellite is made up of many small antennas that can connect existing smartphones, distinguishing the company from Starlink and other planned constellations that currently rely on antennas or ground dishes.
To determine the specific impact of BlueWalker3, the authors of the new study collected observations of the satellite recorded by amateur and professional astronomers in Chile, the United States, Mexico, New Zealand, the Netherlands and Morocco. This global campaign revealed that BlueWalker3 reached a magnitude that made it as bright as Procyon and Achernar, two of the 10 most luminous stars in the sky, according to the study.
“I really like how they used many different telescopes from many different places in the world; highlights how this is truly a global problem,” said Samantha Lawler, an astronomer at the University of Regina in Saskatchewan who was not involved in the study but wrote an accompanying Nature paper. “A country or a small company launches a satellite and it can be seen everywhere in the world.”
AST SpaceMobile said it was working with astronomers on techniques to reduce disturbances. He also compared the number in his constellation to the tens of thousands predicted by other companies. The spokesperson said it could “provide substantial global coverage with around 90 satellites.”
Although BlueBird satellites would be much fewer in number, they are at least 64 times larger and brighter than a Starlink satellite. SpaceX’s orbiters are also brighter in the days after they deploy, but become much dimmer once they settle into their target orbits.
Astronomers expect the BlueBird satellites to remain bright in the sky for most of their lives. As a consequence, one of these satellites could interfere with the data captured by astronomical observatories.
“They are so bright that they will ruin entire images taken with large-scale telescopes, like the Vera Rubin Observatory, for example,” Dr. Eggl said.
There are currently no regulations preventing companies from launching bright, bulky satellite constellations, although many scientists and dark-sky advocates, including indigenous rights groups, are defending the rules. And while many companies are working to darken their satellites, they continue to launch them at a dizzying pace.
“We should not make progress at any cost,” Dr. Tregloan-Reed said. “It’s like building a new development on a historic site. You can’t just do that. You have to protect these things. “
He also acknowledged that astronomers do not own the night sky, but they have a great interest in preserving it.
“What we would like to do is share the night sky and get the public to understand that this is a potential problem,” he said.
