Reflections produced by a growing number of satellites orbiting Earth could ruin more than 95% of images captured by some space telescopes in the next decade, according to a NASA-led study.
The reflected light appears as stripes called satellite trails. This has already been observed in images taken by NASA’s Hubble Space Telescope. The situation is only getting worse as more satellites accumulate in orbit, according to researchers.
The study, published in Nature on Wednesday, predicts that other telescopes could produce images full of stripes, including NASA’s SPHEREx, the European Space Agency’s ARRAKIHS, and China’s Xuntian Space Telescope. SPHEREx was launched this year, while ARRAKIHS and Xuntian have not yet been launched.
A valuable image can emerge when “you’re observing a galaxy and suddenly a very, very distant star explodes,” says Alejandro S. Borlaff, the study’s lead author and a NASA scientist. But “if a satellite happens to cross by chance, you’ll lose that information forever,” he told Nature in a podcast interview.
The problem has grown in recent years: More satellites have been launched in the last four years “than in the previous 70 years of spaceflight combined,” Borlaff said.
More than 10,000 active satellites are in orbit as of December 1, according to data from Jonathan McDowell, astrophysicist at the Harvard-Smithsonian Center for Astrophysics. Most of them belong to SpaceX — the company has more than 7,800 Starlink satellites in orbit.
The International Telecommunication Union (ITU), which oversees proposed satellite applications in space, says there are “thousands more satellites” planned to be launched into orbit.
Between 2018 and 2021, when there were fewer satellites in orbit, about 4% of Hubble Space Telescope images showed satellite light streaks, according to another study published in Nature Astronomy in 2023.
But Borlaff and others predict that this number could increase, with at least one in every three images taken by the Hubble Space Telescope showing a light streak.
“It’s an impressive number. It’s really very high compared to what we see now,” Borlaff told Nature‘s podcast. “In the case of the SPHEREx, ARRAKIHS, and Xuntian telescopes, we expect about 96% of images to be contaminated in some way.”
Borlaff’s study and others show that the increase in satellites could also impact images taken by ground-based telescopes.
The scientific community and astronomers have long been concerned about satellite trails affecting images.
The American Astronomical Society (AAS) warned that an increase in satellites in low Earth orbit could cause collisions with space telescopes and create reflections and light streaks in telescopic images.
“We will continue to facilitate collaborative work with federal agencies and the satellite industry to fully understand and minimize the impacts of large satellite constellations on astronomy,” said Roohi Dalal, AAS Deputy Director of Public Policy, to NPR in a statement on Sunday.
NPR contacted SpaceX for comment on Saturday but received no response. SpaceX has previously said it is taking steps to reduce the light emitted by its satellites, including testing darker coatings, adding sunshades to block sunlight, and adjusting their orbits to reflect less sunlight.
The ITU has also expressed concern about the rapid increase in satellites in space. In a recent report, the UN agency said this “poses significant risks to space sustainability, including collisions and debris generation, threatening the long-term viability of orbital resources.” It called for stricter international rules on the number of satellites in space and better management of satellite networks.
Source: npr.org by Chandelis Duster