When satellites outshine the stars

Since the launch of Sputnik I, the first artificial satellite, in 1957, the ambit of these has grown to fulfill myriad functions, from communication to weather forecasting, GPS, and research. Over time, several private players, too, have entered the fray, cluttering the market, both on Earth and in space. The result: satellite constellations are outshining those of stars, posing a challenge for astronomers, and their quest to study the universe.

Writing in a series of papers published in Nature Astronomy, astronomers have warned about light pollution and how it is a threat to their profession. Since 2019, the number of satellites in the low Earth orbit (LEO) has doubled. This rapid development follows the launch of the first mega-constellation consisting of thousands of satellites by Elon Musk’s SpaceX. The company is putting up a satellite internet constellation, called Starlink, in space to offer satellite internet. Starlink already consists of over 3,500 satellites in the LEO. Last month, OneWeb, the low Earth orbit (LEO) satellite communications company, deployed 36 more satellites into space taking its count of OneWeb’s constellation to 618 satellites. E-commerce giant Amazon, too, plans to start its project Kuiper constellation later this year. While this can be seen as a great side of space technology, astronomers are alarmed.

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The increasing number of satellites increases the risk of these smashing into other objects that orbit the Earth, resulting in space debris. The collisions result in smaller debris compounding the space junk. This reflects light back to Earth. In a paper, researchers have for the first time calculated how much the brighter night sky would affect the work at a major observatory, both scientifically and financially. Over the next decade, at the Vera Rubin Observatory in Chile, where a giant telescope is being constructed, the darkest part of the night sky would become 7.5% brighter, the modelling suggested. This brings down the number of stars the observatory can see by about 7.5%, AFP reported quoting study co-author John Barentine. Not just that, this light pollution limits the number of events in the universe that we are able to witness, the scientist added. Notably, the current measurement of light pollution is significantly underestimated, as per another Nature study, which was based on extensive modelling. It does not end here. “Space is our shared heritage and ancestor — connecting us through science, storytelling, art, origin stories, and cultural traditions — and it is now at risk,” Aparna Venkatesan, an astronomer, wrote in a comment piece in Nature.

Writing in a Nature comment piece, astronomers from Italy, Portugal, and Spain said, “The loss of the natural aspect of a pristine night sky for all the world, even on the summit of K2 or on the shore of Lake Titicaca or on Easter Island is an unprecedented global threat to nature and cultural heritage.” “If not stopped, this craziness will become worse and worse,” they wrote.

The group of astronomers has asked for reining in these mega-constellations. They went on to say that banning them outright cannot be ruled out. However, with the corporate interests involved, that is hardly probable. Despite the grim scenario for astronomy, a group of researchers is looking at the brighter side.

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According to New York Times, a group of experts at Louisiana State University intends to share a proposal with these space-tech companies. The intent is to get several tiny gamma-ray detectors a ride to space on these satellites. The group is led by Dr Eric Burns, an astronomer at Louisiana State University. When working together, these gamma-ray detectors can be as strong as Fermi and Swift, which are gamma-ray observatories managed in space by NASA. Taken alone, each individual detector would be weak. But operating together inside a mega-constellation of many thousands of satellites, the power of such a system would rival Swift and Fermi, two gamma-ray observatories in space that are managed by NASA (National Aeronautics and Space Administration), the US space agency, the media house reported.

These might help in the study of the universe, such as into questions such as what constitutes the core of a neutron star, etc. However, none of the companies have said anything about this.