The Hubble telescope faces the threat of satellites from SpaceX and other companies

The Hubble Space Telescope, known for taking stunning images of the cosmos while advancing the field of astronomy, is under threat.

Private companies are launching thousands of satellites that are bombarding the telescope, producing long bright beams and light curves that may be impossible to eliminate. And the problem only gets worse.

TO study, published Thursday in the journal Nature Astronomy, reveals an increase in the percentage of images recorded by Hubble that are marred by passing satellites. And the data only goes as far as 2021. Since then, SpaceX and other companies have launched thousands more satellites, with many more expected to go into orbit in the coming years, affecting Hubble and potentially other telescopes in space.

“We are going to live with this problem. And astronomy will be affected,” said Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics who was not involved in the study. “There will be science that cannot be done. There will be science that will be significantly more expensive to do. There will be things we will miss.”

The legacy of the Hubble Space Telescope cannot be underestimated. Thanks to the observatory, we now know, for example, that the universe is 13.8 billion years old, that most galaxies contain a supermassive black hole at their center, and that stars form in violent processes. The Hubble images, including the beautiful clouds of gas and dust in the “pillars of creation” and the view of nearly 10,000 galaxies in the “Hubble Ultra Deep Field” — never stop inspiring.

But the number of satellites in orbit has increased significantly since Hubble launched in 1990, and now it’s looking out at the cosmos through a field of satellites.

In May 2019, SpaceX launched its first batch of Starlink satellites, designed to transmit internet signals around the world. Soon after, an outcry arose among astronomers who were concerned that Starlink’s lightning would jeopardize a series of campaigns to observe the universe from telescopes on Earth.

In response, Elon Musk, founder and CEO of SpaceX, He suggested that astronomers get around the problem by moving telescopes into orbit.

But Hubble, which lives in low Earth orbit about 335 miles above Earth’s surface, actually resides less than 10 miles below most Starlink satellites. That means the observatory and other orbiting space telescopes still face interference from constellations of satellites. “Not only do you have to put your telescopes in space, but you also have to put them above all other traffic,” said Dr. McDowell.

“I think we will be forced to do that for decades to come,” he said. But that’s not possible for current telescopes in low-Earth orbit or the spacecraft that governments are building and launching in the coming years.

To quantify the effect of satellite constellations on Hubble, Sandor Kruk, an astronomer at the Max Planck Institute for Extraterrestrial Physics in Germany, and colleagues analyzed an archive of images taken from 2002 to 2021.

They had the help of hundreds of citizen scientists who pored over the images to label those with clear satellite streaks. That data set was then used as a training set for a machine learning algorithm that analyzed more than 100,000 individual Hubble photos. Their results show that the chance of seeing a satellite in a Hubble image from 2009 to 2020 is only 3.7 percent. But the chance of seeing one in 2021 is 5.9 percent, an increase they say corresponds to Starlink. As of the date of the analysis, 1,562 Starlink satellites were in orbit. Another company, OneWeb, had launched 320 satellites.

Mark McCaughrean, an astronomer at the European Space Agency and co-author of the new study, is confident in his analysis, but notes that this is only a minor issue at this point. Typically, Hubble takes multiple images that are stacked on top of each other, a technique that will wipe out any satellite.

And NASA agrees. “While such analyzes may show a gradual increase in detected satellite trails over time, most of these streaks are easily removed using standard data reduction techniques, and most affected imagery is still usable,” he said. a spokeswoman regarding the latest study. “Satellite streaks currently do not pose a significant threat to Hubble’s scientific efficiency and data analysis.”

That threat is greatest when Hubble surveys a large swath of the sky. So you could take just one or two images before redirecting your camera. If a satellite photopumps one of those images, the image may need to be discarded.

Also, the satellites could pose a serious threat to a telescope that has yet to be launched. Later this year, China plans to send Xuntian, also known as the Chinese Exploration Space Telescope, into low-Earth orbit. Xuntian will have a larger field of view than Hubble, making it difficult for satellites to go unnoticed.

“It’s going to be very badly affected by these satellites early on,” said Dr. McDowell.

And Xuntian can’t just launch into a higher orbit. China’s plan is for the telescope to share an orbit with the Tiangong space station so astronauts can restore it if necessary.

A SpaceX spokesperson declined to comment on the new study, but noted the company’s previous efforts to mitigate the effects of Starlink. The company has tried a variety of methods to obscure its satellites, including a mirror film designed to divert light from the ground. But Meg Schwamb, a planetary scientist at Queen’s University Belfast who was not involved in the study, worries that the light is directed upwards and could make the situation worse for space telescopes.

There are just too many unknowns right now, including the final number of satellites.

SpaceX hopes to eventually expand its fleet size to 42,000 Starlink satellites. Many other companies are also in the market: Amazon, the British satellite provider OneWeb, a Chinese company called Galaxy Space, and even governments. a mix 431,713 satellites it is planned to launch in the next few years.

“It’s a bit of a feeding frenzy right now,” Dr. McCaughrean said.

That estimate is based on filings with the US Federal Communications Commission and the International Telecommunications Union. But even if only 100,000 satellites were launched, that would increase the number of satellites in orbit by a factor of 10 since the new study was done, meaning that roughly 50 percent of Hubble images would detect a satellite. And if all other images were to have a satellite streak, researchers worry about how much useful science could be gleaned.

“When will Hubble stop being useful?” asked Dr. McCaughrean. “That may be 10 or 20 years away, but it’s not inconceivable that there’s a point where you say, ‘Let’s not bother anymore.'”