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Post: Astronomers warn of light pollution from satellites


Space pollution by the proliferation of satellites in orbit is disrupting observation and monitoring telescopes to the point of threatening the future of the profession, warn two studies whose authors call for action to change this reality.

And since the American company SpaceX in 2019 began to receive a constellation system formed by thousands of satellites sent in groups, the number of these satellites has doubled and the projects continue to maintain a high flow in the field. communications through them.

A large number of satellites in low orbit (at an altitude of up to 2 thousand kilometers) causes a strong movement of these devices, which increases the risk of collision with each other. Through successive reactions, the collisions produce additional amounts of debris that break into smaller fragments, increasing the size of the debris cloud that reflects light back to Earth.

A study published Monday in the journal Nature Astronomy shows that what is happening has “terrifying” consequences for astronomy due to the “unprecedented” change in the night sky.

For the first time, astronomers tried to measure the reduced efficiency of observations due to this contamination and estimate the costs.

By reflecting sunlight, satellites increase the effect of light pollution. Some companies, including SpaceX, have tried to dim the light emitted by their devices to lessen the problem.

However, effects caused by small debris are more problematic, as ground-based telescopes cannot track all debris due to its very small size.


John Barrantin, one of the authors of the study, explained to AFP that the images from the telescopes are contaminated by the large number of light trails they create and “the light reflected from the debris continues to illuminate the sky”.

All of this is a big loss for scientific projects like the Vera C. Rubin Observatory, a giant telescope under construction in Chile. In the next decade, the brightness of the night sky will increase by 7.5%.

“This will extend the life of the mission of the program for one year, at an additional cost of approximately $ 21.8 million”, says Barrantini, researcher at the American University of Utah, and adds that the benefit outweighs with increases in “time and Money. We’re already losing.” Due to other factors such as the weather.

Another study, published in Nature Astronomy, confirmed that the result could be worse because current measurements of light pollution do not adequately measure this phenomenon.

Among other effects is the loss of opportunities to observe rare and unknown astrophysical phenomena, while some of them, such as the passage of meteorites, are so subtle that the sky must be clear to observe them.

Even in a polluted location like the one where the Vera C. Rubin Observatory is located, a 7.5% increase in night sky brightness would reduce the number of stars the observatory could detect.

A legacy at risk

As light pollution on Earth continues to increase, suitable sites to build telescopes are shrinking, as a large number of researchers attest in articles accompanying these two studies.

However, the phenomenon goes beyond the scientific aspect and affects the “ancestral relationship” that unites humanity with the night sky, and should be seen as “intangible heritage” of humanity, says astrophysicist Aparna Venkatesan, from the University of San Francisco. .

Scientists point out that “the loss of darkness that reached the summit of K2 and the shores of Lake Titicaca and Easter Island is a threat to the environment and our cultural heritage”.

“We want to get rid of light pollution, but we end up seeing thousands of moons,” says astrophysicist Eric Lagadec, who was not involved in any of the studies.

The authors of the two studies call for the limitation of satellite constellations or even their complete ban, stressing that any other measure to reduce their effects would not be effective.

They conclude that “it is naive to think that the launch vehicle market will be regulated without restrictions”, given the economic interests at stake.

Source: EuroNews

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