It has been three years since SpaceX, a space company in Hawthorne, California launched its first set of Starlink Internet-communication satellites, causing astronomers to worry about the sequence left by satellites in the night sky. Since then, many more Starlinks have been established: more than 2,300 of them now orbiting the Earth, covering almost half of all active satellites.
How satellite imagery mega-constellations will explode star
Scientists have made some advances in dealing with these attacks. For example, within days the International Astronomical Union (IAU) will launch a website that includes tools to help televised pilots predict satellite locations so that they can point their devices elsewhere1.But the cumulative evidence indicates how much of the satellite’s ‘constellations’ will affect astronomical observatories and other observatories around the world. Satellite companies have not yet found a solution. SpaceX was trying to fix the problem by adding sunscreens to its Starlinks to obscure their appearance in the night sky. But Nature has found that the company has stopped doing that.
Tens of thousands of new satellites could be introduced in the next few years. “This is a bad trail,” said Meredith Rawls, an astronomer at the University of Washington in Seattle. “At the moment our science is right. But when can we miss the discovery?.
Number of mega-constellations
Since the launch of the first Starlinks, astronomers have stopped worrying about satellite tracking satellites to plan a global response. Following a series of international workshops in 2020 and 2021, the IAU established a Black and Silent Sky Protection Center on Satellite Constellation Disruption. Its soon-to-be launched website is designed to serve as a base for astronomers, policymakers, satellites and the public to coordinate ways to reduce the impact of satellites in the atmosphere.
The launch of SpaceX highlights the threat of astronomy from ‘megaconstellations’Recent study suggests that future satellite astronomical observations are the most visible during the summer nights at about 50 degrees south and 50 degrees north, where many European and Canadian star centers are located2. When SpaceX and other companies launch the 65,000 satellites they have proposed, bright dots will be heard throughout the night at those latitudes around the summer solstice, the study said. In the hours leading up to sunrise and sunset, about 1 in 14 star-shaped stars will actually be satellites.
“It’s really scary,” said Samantha Lawler, an astronomer at the University of Regina in Canada, who led the project.Astronomers who study the atmosphere instead of focusing on the celestial bodies will be greatly affected. The Zwicky Transient Facility (ZTF), which scans the horizon using a 1.2-meter telescope at Palomar Mountain, California, has satellite streaks on 18% of its images taken during the night of August 20213. And that number has increased as the numbers satellites are widespread, says lead author PrzemekMróz, an astronomer at the University of Warsaw. He performed the first ZTF data analysis since April 2022 and found that satellite tracking affected approximately 20-25% of twilight images.
To date, the ZTF has not had many of its measurements damaged by satellite streaks, in part because its image processing systems are able to detect and block satellite channels, MrMróz said. But other observatories face major challenges – especially the Vera C. Rubin Observatory, a US-based 8.4-meter-wide telescope built and built in Chile. Because it will capture the entire visible sky every three days, it will be particularly vulnerable to satellite tracking. Rawls and other astronomers work on ways to reduce damage, such as algorithms that can detect and clear satellite sequences in data. But data processing still takes a lot of time and energy. “It really costs my work,” Rawls said.
Busy sky
A growing number of satellites also threaten to disrupt the field of radio astronomy and increase the amount of space debris. Also, a wide range of impacts could affect global health: the presence of satellites contributes to the background light in the sky that can confuse animals that rely on celestial orbit. Satellite tracking can also affect human information systems, such as Indigenous information systems that rely on information from the dark sky to mark important events throughout the year4.SpaceX explores black satellite to reduce the threat of ‘megaconstellation’ in astronomy The growing threat of satellites adds to another nightmare such as light pollution, says Karlie Noon, PhD candidate in astronomy and Indigeneous research partner at Australian National University in Canberra. “In the same way that our lands were taken over by the colonies, our sky is now controlled by the colonies,” he said. “And this is not just Indigenous people.” He points out that companies make satellites without consulting the scientific community.
Some satellite operators were working to reduce the problem. Companies including SpaceX, OneWeb in London and Amazon’s Project Kuiper in Seattle, Washington, have regularly met with the IAU and the national astronomical community about ways to reduce the impact of satellites. SpaceX has explored ways to obscure its Starlinks, including including solar panels. Sunshades reduce satellite light5, but seem to have been abandoned in the later generation of Starlinks. Those satellites, launched in September, use laser instead of a radio to communicate, and the sun’s rays interfere with that communication.
SpaceX instead operates other mitigation measures such as adding stickers or other objects to the satellite imagery to reflect light away from Earth, said David Goldstein, the company’s engineer, during a webinar hosted by the UK-based Federation of Astronomical Societies (FAS) earlier this year. horn.
How well that might work is still being worked out. An unpublished analysis of the 102 starlinks recognition over time suggests that those from the younger generation appear to be much brighter than those known for having sunshades. However, they do not shine like the original Starlinks without solar panels, says Anthony Mallama, a retired astronomer in Bowie, Maryland, who conducted the analysis.
At that time, OneWeb launched the 428 pre-programmed set of 648 satellites. They circled at higher altitudes than the Starlinks – 1,200 kilometers compared to 550 kilometers. Satellites are usually much smaller than Starlinks simply because they are farther away, but they may vary slightly in brightness depending on whether they capture and reflect sunlight.
One first study of OneWeb 50 satellites in 2021 found that about half of them were slightly shorter than the ‘safe’ limit stated by astronomers, says Jeremy Tregloan-Reed, an astronomer at Atacama University in Copiapó, Chile. OneWeb says it is committed to reducing the visibility of its satellites; uses the Sicily telescope to measure their brightness and draws on that knowledge to design future weak satellites, Maurizio Vanotti, OneWeb’s vice president of space infrastructure development and collaboration, told the FAS webinar.
Astronomers are pushing for a global debate over the massive satellite system
Amazon’s Project Kuiper, which can add more than 3,200 satellites, plans to launch its first 2 satellites later this year. One of them will contain sunlight so the company can compare its ability to dim the satellite light.There are no rules governing how bright satellites should appear in the night sky, although the IAU and other astronomical organizations have been pressuring the United Nations to identify the problem. Delegates from many nations will discuss air protection at a United Nations Committee on Foreign Peace Beginning in Vienna on June 1.
Source Journal Reference:Alexandra Witze, ‘Unsustainable’: how satellite swarms pose a rising threat to astronomy, Nature News (2022), doi: https://doi.org/10.1038/d41586-022-01420-9, https://www.nature.com/articles/d41586-022-01420-9
