Turns out a recently launched satellite is almost as bright as the brightest stars (and that’s a problem)

Turns out a recently launched satellite is almost as bright as the brightest stars (and that's a problem)

When fully operational, the 8 x 8 meter satellite will shine as brightly as Procyon, the eighth brightest star in the night sky. This leads to great frustration among astronomers.

When the BlueWalker 3 satellite was launched last year, it immediately caused a stir. Astronomers fear that the satellite, especially because of its enormous size and the brightness it emits, will make observing the night sky difficult. Unfortunately, this fear has now become a reality. Because satellite observation shows that it is one of the most striking objects in the night sky, with all the ensuing consequences.

More about the BlueWalker 3 satellite
The BlueWalker 3 satellite, developed by AST Space Mobile, was launched and placed into low Earth orbit on September 10, 2022. This satellite serves as a prototype for an envisioned future network of 243 similar satellites designed for mobile communications. The goal is to make mobile or broadband services available worldwide, regardless of location. Ordinary mobile phones should be enabled for direct communication via satellite, especially in areas where mobile coverage is weak or non-existent. Because the signals from regular cell phones are relatively weak (they’re designed to reach a cell tower within a limited distance, not a satellite 450 miles away), the satellite has a massive 8-by-10-inch phased array antenna. meter. This antenna acts as a mirror and reflects sunlight back to Earth.

Artist’s impression of the BlueWalker 3 satellite, fully expanded here. Image: AST Space Mobile

Satellites orbiting the Earth can appear bright because they reflect sunlight. Think back to Starlink satellites, which were also of great interest at the time. But it’s the BlueWalker 3 satellite that really takes the cake. This is mainly due to its enormous size. The satellite has a large area of ​​64.3 square metres, and is the largest commercial antenna system ever placed in low Earth orbit. Given its size, it logically reflects a lot of sunlight. This makes the satellite as bright as the brightest star in the sky.

The brightest stars
In a new study, researchers calculated the brightness of the BlueWalker 3 satellite. The results are alarming. When fully operational, the 8 x 8 meter satellite will shine as brightly as Procyon, the eighth brightest star in the night sky. Procyon, along with the star Achernar, is one of the brightest stars in the constellation Canis and Eridanus. In addition, BlueWalker 3 sometimes becomes hundreds of times brighter than international guidelines recommend.

Astronomers are not happy at all. The enormous brightness of BlueWalker 3 could blind the sensitive instruments that astronomers use to scan the night sky. This makes astronomical observations useless. Astronomers are therefore very concerned about the potential impact of a vast network of these exceptionally bright satellites on sensitive observing equipment. “The night sky is a unique environment that allows scientists to conduct experiments that go beyond the capabilities of terrestrial laboratories,” explains researcher Dave Clements. “Astronomical observations have given us insight into the fundamental principles of physics and contributed to research that has expanded the frontiers of our knowledge. Moreover, they have changed our human view of our place in the universe. The pristine night sky is also an important part of our shared cultural heritage and should be preserved for society as a whole and for generations.” Coming.

The light trail left by BlueWalker 3 above the National Astronomical Observatory in San Pedro Martir, Mexico. Photo: I. Blauchow-Frain

Dutch amateur astronomer Marco Langbroek also suspects that satellites like BlueWalker 3 will cause serious problems. “Hundreds of these types of objects in the sky could pose a problem for astronomical observing programs,” he says. “For example, the Vera Rubin Observatory in Chile is currently being built with a very large sensitive telescope that will map the southern hemisphere sky every night. These satellites will inevitably be ‘seen’ and the telescope’s sensitive sensors will be temporarily blinded. In addition, the frequencies The radio used is close to some frequencies that are of interest to radio astronomers, and there is a fear of radio interference.”

Radio interference
Although some telescopes are located in specially designated radio-quiet zones, current regulations designed to protect these zones only apply to ground-based transmitters. This means that they are not necessarily protected from interference caused by satellite broadcasts. “Current measures to protect observatories from radio interference may seem inadequate,” said researcher Mike Bell. “It is therefore necessary to conduct more research and develop strategies to protect current and future telescopes from the large number of satellites that will be launched over the next decade.”

But not only that. Langbroek claims that if many bright objects move across the sky on a regular basis, this will inevitably lead to a change in the shape of our night sky. “This is indeed the case,” he says. “That starry sky belongs to all of us. Companies like AST Space Mobile make unilateral decisions that have a huge impact on our starry sky, without consulting the rest of the world. Don’t forget that the starry sky plays a major (cultural) role for people on Earth: think of a romantic evening Under the starry sky, but also many legendary stories are related to this. The starry sky is a piece of nature, a heavenly landscape, also worthy of protection. It is a pity that the starry sky is no longer clearly visible in many places in our Western world. But not We are able to avoid the “light pollution” caused by these types of satellite networks. Even from the darkest and most remote places on Earth, these satellites will be visible.

Langbroek therefore calls for better legislation to keep space under control. “There’s actually no legislation that specifically deals with this kind of filibuster problem,” he explains. “Part of this has to do with the fact that creating these kinds of networks with hundreds or even thousands of satellites is a very recent development. This has caught us, astronomers, but also legislators, by surprise. Arranging international legislation through the United Nations It will be a very long process, while developments are underway now and moving very quickly. Regulation may be possible more quickly through legislation at the national level in countries that have launched this initiative such as the United States. Personally, I think there should be a serious debate about whether We really needed these types of networks.

While researchers acknowledge that the emergence of new constellations of satellites plays an important role in improving global communications, they stress that the disruption of astronomical observations by these satellites poses serious obstacles to progress in our understanding of the universe. Therefore, they say that the implementation of such satellite networks should be carefully considered, with a focus on minimizing their negative impact on astronomy. “Space is now like the Wild West, where anyone with enough money can do whatever they want,” Langbroek says. “It’s time for the police chief to bring order to the chaos out there.”

Astronomers will continue to monitor BlueWalker 3 and have plans to study its thermal emissions later this year. This topic will also be discussed in October at the upcoming International Astronomical Union Symposium on Astronomy and Satellite Constellations.

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