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‘Worrying trend’ – Experts see an ‘increasingly pressing problem’ in the sky

‘Worrying trend’ – Experts see an ‘increasingly pressing problem’ in the sky

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Launch of the “Blue Walker 3” long-exposure satellite. The satellite’s large brightness is a concern for astronomers. (Archive photo) © IMAGO/JOE MARINO

More and more satellites are orbiting the Earth – and this does not go unnoticed by astronomers. One satellite in particular is currently of research concern.

COPIAPO – When the Blue Walker 3 satellite was lifted into space by a SpaceX rocket a year ago, astronomers were apprehensive. Experts at the time feared that the large satellite would become one of the brightest objects in the night sky. At the end of 2022, measurements showed that the satellite operated by operator AST SpaceMobile is actually brighter than most stars in the night sky. Now, an international research team has published a study with new details about the “Blue Walker 3” satellite and its impact on astronomy.

“The impact of satellites on astronomy has become an increasingly pressing problem in recent years,” emphasizes lead author Sangeetha Nandakumar (University of Atacama, Chile). This mainly concerns Elon Musk’s SpaceX “Starlink” satellite constellation. There are now more than 4,800 of these satellites in low Earth orbit, and even if things improve over time, they can still be seen brightly in the sky.

Starlink satellites can be seen brightly in the sky – and more constellations are planned

Even before Starlink satellites, Earth’s satellites could be seen in the sky for short periods of time – such as the International Space Station (ISS), which can sometimes be seen very brightly in the sky. But the problem only appeared with Starlink satellites. With several additional “Starlink” satellites and constellations from other providers planned, astronomy is now worried.

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“The night sky is a unique laboratory where scientists can perform experiments not possible in terrestrial laboratories,” explains co-author Dave Clements (Imperial College) in one of the articles. notice He continues: “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 universe.” He said the clear night sky is also an important part of humanity’s common cultural heritage. researcher.

Study: The “Blue Walker 3” satellite is too bright – and disrupts astronomy

Data from professional and amateur observers were used in the study In the specialized magazine nature published Summarized and shown: After BlueWalker 3 fully opened its antennas, it suddenly became noticeably brighter. And no wonder: at 64 square metres, the satellite contains the largest commercial antenna system ever used in low Earth orbit.

Thanks to observations from Chile, the USA, Mexico, New Zealand, the Netherlands and Morocco, scientists were also able to calculate the satellite’s path 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 objects from interfering with recordings, for example.

Study identifies a scary satellite trend

As the study shows, Blue Walker 3 can disrupt not only astronomy operating in the visible range, but also radio astronomy. The satellite uses wavelengths similar to radio telescopes. What is especially tragic is that some radio telescopes are located in so-called “radio quiet zones” where transmitting disruptive radio signals is prohibited. But these restrictions only apply to ground signals, as satellites have so far been able to interfere with radio telescopes from above. Study co-author Mike Bell (Imperial College) admitted: “More research is needed to develop strategies to protect existing and future telescopes from the numerous satellites scheduled to be launched over the next decade.”

Researchers involved in the study identified a frightening trend for astronomy and called for action: “These results show a continuing trend toward larger and brighter commercial satellites, which is particularly concerning, given plans to launch more satellites in the coming years.” Confirms co-author Siegfried Eagle (University of Illinois).

Bright satellites provide communication – and disrupt research

The researcher emphasizes: “While these satellites can play a role in improving communications, it is necessary to reduce their interference with scientific observations to a minimum.” This would preferably be achieved through continued cooperation on mitigation efforts, or failing that, by requiring a pre-launch impact assessment as part of future launch licensing processes.

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The topic is not an easy matter for astronomy, as researchers confirm. “The astronomy community understands the need for greater connectivity and improved Internet access, especially for rural and underserved communities,” explains co-author Jeremy Tregloa Reid (University of Atacama Chile) in his article. notice. However, progress must be weighed against the negative impact satellites can have on the night sky.

Regulating satellite launches is a problem

Treglo-Reid sees one problem with regulation: “It is a global problem, as satellites approved by any country can be seen in the night sky all over the world, which underscores the importance of international coordination.” AST SpaceMobile plans to send 90 more satellites. Satellites into space “in the near future” to improve Internet reception. One thing is already certain: the Blue Walker 3 satellite will continue to be monitored. (unpaid bill)