A new satellite outshines some of the brightest stars in the sky

Last November, a satellite in low Earth orbit deployed into a sprawling array spanning nearly 700 square meters, about the size of a studio apartment.

The BlueWalker 3 satellite has since become one of the brightest objects in the sky, outshining some of the most luminous stars in the Milky Way. a study published Monday in Nature – and it’s just the first of dozens of similar satellites in development by AST SpaceMobile, a company that aims to keep smartphones connected from space.

Astronomers were already concerned about the rise of mega-constellations of satellites, such as SpaceX’s Starlink, which have shiny surfaces that sometimes obscure the view of space from the ground. The launch and implementation of BlueWalker 3 have exacerbated these concerns.

“The problem is not necessarily that one satellite,” says Siegfried Eggl, an astrophysicist at the University of Illinois, Urbana-Champaign and author of the new study, “but that it is a precursor or prototype of a constellation, so there will be ultimately be a lot of it.

Initially launched in September 2022, BlueWalker 3 is the precursor to AST SpaceMobile’s BlueBird satellites, which aim to serve as a network of orbital cell towers with the aim of “democratizing access to knowledge and information no matter where people live and work,” said a spokesperson. said for AST SpaceMobile. Last month BlueWalker 3 was successful has delivered its first 5G connection to a smartphone in a cellular coverage gap on Earth.

AST SpaceMobile is one of many companies racing to meet the rising 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 services to customers around the world. Other companies, such as Amazon (which is expected to launches its first prototype satellites on Friday) and OneWeb have similar ambitions, and many countries are developing their own communications mega-constellations.

“Right now there are 18 constellations that we know are planned around the world,” said Dr. Eggl. “The total number of satellites is an astonishing half a million that people want to put there. This is a hundred times more than we already have.”

The proliferation of satellites in recent years has alarmed stargazers from all walks of life. As spacecraft move through the sky, they create bright trails and an ambient glow in the sky that can destroy astronomical images and obscure fainter celestial bodies that would otherwise be visible to the naked eye.

“It’s going to be a big change for these constellations,” said Jeremy Tregloan-Reed, an astronomer at the Universidad de Atacama in Chile and author of the study.

AST SpaceMobile has scaled BlueWalker 3’s array to deliver strong cellular coverage directly to phones on Earth. The satellite is made of many small antennas that can connect existing smartphones, an approach that sets the company apart from Starlink and other planned constellations that currently rely on ground antennas or dishes.

To find out the specific impact of BlueWalker 3, 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 BlueWalker 3 reached a magnitude that made it as bright as Procyon and Achernar, two of the ten most luminous stars in the sky, according to the study.

“I really like how they used lots of different telescopes from lots of different places around the world; it 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 a paper in Nature that accompanied it. “One country, or one small company, launches a satellite and it can be seen all over the world.”

AST SpaceMobile said it is working with astronomers on techniques to reduce disruptions. It also contrasted the number in its constellation with the tens of thousands planned by other companies. The spokesperson said it could “provide substantial global coverage with approximately 90 satellites.”

Although the number of BlueBird satellites would be much smaller, they are at least 64 times as large and bright as a Starlink satellite. The SpaceX orbiters are also brightest in the days after their deployment, but become much fainter once they enter their target orbits.

Astronomers expect the BlueBird satellites to remain bright in the sky for most of their lives. As a result, one of these satellites could disrupt the data recorded by astronomical observatories.

“They are so bright that they ruin entire images taken with large-scale telescopes, such as the Vera Rubin Observatory,” said Dr. Eggl.

There are currently no regulations preventing companies from launching bright and sizable satellite constellations, although many scientists and dark sky advocates, including indigenous rights groups, are calling for regulations. And even though many companies are doing their best to make their satellites darker, they continue to launch them at a breakneck pace.

“We shouldn’t make progress at any cost,” said Dr. Tregloan Reed. “It’s like building a brand new project on a historic location. You can’t just do that. You have to protect these things.”

He also recognized that astronomers do not own the night sky, but do have an interest in preserving it.

“What we’d like to do is share the night sky and help the public understand that this is a potential problem,” he said.