2023-10-23 04:55:37
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The launch of the “BlueWalker 3” satellite in a long exposure. The brightness of the large satellite is a concern for astronomers. (Archive image) © IMAGO/JOE MARINO
Astronomy is threatened by bright satellites. An international research team is calling for urgent action.
Copiapó – The “BlueWalker 3” satellite has been orbiting the earth for regarding a year. Even before its launch, experts feared that the large satellite one of the brightest objects in the night sky might advance. At the end of 2022, measurements confirmed that the operator AST SpaceMobile’s satellite actually shines brighter than most stars at night. Now an international team of scientists has conducted a study with new details regarding the “BlueWalker 3” satellite and its effects on the Astronomy published.
„Die Influence of astronomy by satellites has become an increasingly pressing problem in recent years,” emphasizes lead author Sangeetha Nandakumar (Universidad de Atacama Chile). This is primarily due to the “Starlink” satellite constellation of Elon Musk’s private space company SpaceX. Over 4,800 of these satellites are already in low Earth orbit and – although the situation has improved over time – are still brightly visible in the sky.
Satellite constellations like “Starlink” disrupt astronomy
Even before the “Starlink” satellites, artificial satellites might often be seen briefly in the sky, such as the International Space Station (ISS), which can occasionally be seen racing very brightly across the sky. But it was only with the “Starlink” satellites that the problem became apparent. Since numerous additional “Starlink” satellites and satellite constellations from other providers are planned, astronomy is now on alert.
“The night sky is a unique laboratory in which scientists can conduct experiments not possible in terrestrial laboratories,” explains co-author Dave Clements (Imperial College) in a notice and adds: “Astronomical observations have provided insights into fundamental physics and other research at the frontiers of our knowledge and have changed humanity’s view of our place in the cosmos.” The pristine night sky is also an important part of humanity’s shared cultural heritage, emphasized the scientist.
The “BlueWalker 3” satellite is particularly large – and very bright in the night sky
In the study, the in the specialist journal Nature published data from professional and amateur astronomers were summarized and show: After “BlueWalker 3” fully extended its antennas, it suddenly became significantly brighter. No wonder: With an area of 64 square meters, the satellite has the largest commercial antenna system ever used in low Earth orbit.
-12,73 mag 5 mag 4,67 mag 2,94 mag 4,46 mag 0,47 mag 0,4 mag 1,97 mag 3,7 mag 4-6 mag
Thanks to observations from several countries, the researchers were able to calculate the satellite’s trajectory and determine how it might change due to factors such as air resistance. Knowing the exact orbit of satellites is particularly important for research because this is the only way to prevent bright celestial bodies from interfering with recordings, for example.
“BlueWalker 3” satellite also disrupts radio astronomy
As the study shows, “BlueWalker 3” can disrupt not only astronomy that works in the visible range, but also radio astronomy. The satellite uses similar wavelengths to radio telescopes. Particularly tragic: Some radio telescopes are located in so-called “radio quiet zones” where disruptive radio signals are prohibited. But these restrictions only apply to terrestrial signals – the satellites have so far been able to interfere with the radio telescopes from above. Study co-author Mike Peel (Imperial College) recognized: “Further research is needed to develop strategies to protect existing and future telescopes from the numerous satellites scheduled to be launched over the next decade.”
The researchers involved in the study identify a worrying trend for astronomy and call for action: “These results show a continued trend towards larger and brighter commercial satellites, which is particularly worrying given plans to launch many more satellites in the coming years is,” emphasizes co-author Siegfried Eggl (University of Illinois).
The scientist believes: “While these satellites can play a role in improving communications, it is imperative that their interference with scientific observations is minimized. This might preferably be achieved through continued cooperation in mitigation efforts or, failing this, by requiring a pre-launch impact assessment as part of future launch authorization processes.”
Either connectivity or dark skies – a problem for astronomy
The topic is not an easy one for astronomy, as the researchers emphasize. “The astronomical community understands the need for greater connectivity and improved internet access, particularly for rural and underserved communities,” explains co-author Jeremy Tregloa-Reed (Universidad de Atacama Chile) in a notice. However, progress must be weighed once morest the negative impact that satellites might have on the night sky.
Tregloa-Reed sees a problem in regulation: “This is a global problem, as satellites approved by any country can be seen in the night sky around the world, highlighting the importance of international coordination.” AST SpaceMobile plans , to send another 90 or so satellites into space “in the near future” to enable better internet reception. Therefore, observation of the “BlueWalker 3” satellite will continue safely. (tab)
Machine assistance was used for this article written by the editorial team. The article was carefully checked by editor Tanja Banner before publication.
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