The BlueWalker 3 satellite whose antenna area is 64 square meters has become one of the brightest objects in the night sky, the fear is that when there are a hundred satellites in this constellation and hundreds in other constellations in low orbit, it will be impossible to observe the sky in the optical field and there will also be interference to the radio field
Clusters of satellites, such as the BlueWalker 3 prototype, are causing concern among astronomers due to possible interference with night sky observations and radio astronomy. Balancing the global needs for communication and maintaining astronomical research is critical. Credit: AST SpaceMobile
Huge communications satellites in low Earth orbit could interfere with astronomy. Observations of the BlueWalker 3 prototype show it to be one of the brightest objects in the night sky, raising concerns that without mitigation, large constellations of satellites could disrupt our ability to observe stars from Earth and perform radio astronomy.
Several companies are planning satellite bands - hundreds of potential satellites that can provide cellular services or bandwidth anywhere in the world. However, these satellites need to be in very low Earth orbit and can be relatively large, so their potential to interfere with observations of the night sky is a concern.
Pictured is a trail left by BlueWalker 3 over the National Astronomical Observatory of San Pedro Martir, Mexico, seen on November 12, 2022. Breaks in the trail are caused by breaks between exposures that were combined to create this image. Credit: E. Palaucho-Frein
The effect BlueWalker 3 on astronomy
BlueWalker 3 was launched into low Earth orbit on September 10, 2022 by AST SpaceMobile, as a prototype for a planned group of more than 100 similar satellites intended for use in cellular communications. Observations made within weeks of launch showed that the satellite was among the brightest objects in the sky.
To better understand its effects on astronomy, the CPS initiated an international observing campaign. As part of this, professional and amateur sightings have been contributed from around the world, from sites in Chile, USA, Mexico, New Zealand, Holland and Morocco.
The newly released data, which includes observations over 130 days, shows a sharp increase that coincides with the full deployment of the antenna array, which at 64 square meters is the largest commercial antenna array ever launched into low Earth orbit.
Some of the observations were also used to calculate the satellite's trajectory over time. By comparing the predicted trajectory with the collected observations, the authors were able to assess the accuracy of the predictions and how the trajectory could change due to factors such as atmospheric drag.
Knowing the locations of the satellites is important so astronomers can try to avoid them or at least know where they will be when analyzing the data.
Radio frequency interference problems
Besides optical observations, BlueWalker 3 may also interfere with radio astronomy, as it uses wavelengths close to those used by radio telescopes for observations. While some telescopes are located in designated radio silence zones, the restrictions in place to preserve these zones currently only apply to terrestrial transmitters, so they are not necessarily shielded from satellite transmission.
Dr Mike Peel, lead partner of IAU CPS's Sathub and researcher in the Department of Physics at Imperial College said: "BlueWalker 3 is actively transmitting at radio frequencies close to bands reserved for radio astronomy, and existing observatory protections against radio interference may not be sufficient. Therefore, further research is required to Develop strategies to protect existing and future telescopes from the hundreds of planned satellites for launch in the next decade".
Looking ahead
The IAU and CPS partners recognize that the new constellations of satellites play an important role in improving global communications. However, their interference with astronomical observations can severely hamper progress in our understanding of the universe. Therefore, their deployment should be done with due consideration of their side effects and efforts to minimize their impact on astronomy.
Astronomers will continue to monitor BlueWalker 3 and other satellites to better understand their effects and develop strategies to protect astronomical observations.
Some of the collected observations were also used to calculate the satellite's trajectory over time. By comparing the predicted trajectory with the collected observations, the researchers could assess the accuracy of the predictions and how they might change due to factors such as atmospheric drag.
Knowing the locations of the satellites is important, so astronomers can try to avoid them or at least know where they will be in the data. However, it is difficult to moderate their brightness beyond their position coverage and data loss for that part of the sky.
One way to reduce the brightness of satellites is to paint them a darker color. However, this still does not completely solve their high brightness problem. Also, there is a need for supervision and enforcement to make sure that the satellites do meet maximum brightness standards.
Ultimately, the challenge is to balance the utility of new communication satellites with the need to protect astronomical research and the night sky as a shared resource for humanity. International cooperation and constructive dialogue between satellite companies, governments and astronomers will be critical to achieve this balance.
Modern astronomy provides insights into fundamental physics and other studies at the limits of our knowledge, and changes humanity's perception of our place in the universe. The pristine night sky is also an important part of humanity's shared cultural heritage and must be protected for the sake of society and future generations.
More research and ongoing discussion is needed to find a way to balance the benefits of new communications satellites with the need to protect astronomical research important to the expansion of human knowledge.
Dr Dave Clements, from the Department of Physics at Imperial College said: "The night sky is a unique laboratory that allows scientists to conduct experiments that cannot be carried out in terrestrial laboratories. Astronomical observations provided insights into fundamental physics and other studies at the limits of our knowledge, and changed humanity's perception of our place in the universe."
Dr Mike Peel, Lead Fellow of the IAU CPS's Sathub and Researcher in the Department of Physics at Imperial College said: "BlueWalker 3 is actively transmitting in radio frequencies close to bands reserved for radio astronomy, and the observatories' existing protections against radio interference may not be sufficient. More research is needed to develop strategies to protect existing and future telescopes."
Sanjith Nandakumar, the principal investigator, said: "We found that the 3x8 meter BlueWalker 8 satellite quickly became one of the brightest objects in the sky, with a maximum brightness of magnitude 0.4. This demonstrates the challenge that large communications satellites pose to astronomy."
The issue will continue to be discussed at the upcoming IAU convention later in October in a panel titled: "Astronomy and Satellite Clusters: Paths Forward."
The scientific article in Nature
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than. with credit
The article is interesting. Is it possible to copy a section of it and post it with credit?
This is a newspaper for radio enthusiasts with a limited circulation.