The Hubble Space Telescope, known for recording stunning images of the universe while advancing the field of astronomy, is under threat.
Private companies are launching thousands of satellites that are bombarding telescopes with light—creating long bright streaks and light curves that can’t be erased. And the problem will only get worse.
A study, published Thursday in the journal Nature Astronomy, reveals an increase in the percentage of Hubble-recorded images destroyed by passing satellites. And the data only lasts until 2021. Since then, SpaceX and other companies have launched thousands more satellites, and many more are expected to enter orbit in the coming years, affecting Hubble and possibly other space telescopes.
“We’re going to live with this problem. Astronomy is going to suffer,” said astronomer Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics, who was not involved in the study. “There will be science that can’t be done. There will be more expensive science. There will be something we miss.”
The legacy of the Hubble Space Telescope cannot be overemphasized. Because of observatories, we now know, for example, that the universe is 13.8 billion years old, that most galaxies have a supermassive black hole at their center, and that stars form in a violent process.Hubble image – including gorgeous clouds of gas and dust in the Pillars of Creation, and a view of nearly 10,000 galaxies in the Pillars of CreationHubble Ultra Deep Field” – always inspiring.
But since Hubble launched in 1990, the number of satellites in orbit has increased significantly, and it is now peering out at the cosmos from its field of satellites.
In May 2019, SpaceX launched the first batch of Starlink satellites, designed to broadcast internet signals around the globe. Soon after, there was an outcry from astronomers who feared that Starlink’s streaks would jeopardize the many observations of the universe from telescopes on Earth.
In response, SpaceX founder and CEO Elon Musk suggestion Astronomers get around this problem by moving telescopes into orbit.
Gazing into space with the Hubble Telescope
Since its launch in 1990, the Hubble Space Telescope has recorded stunning images of the universe while advancing the field of astronomy.
But Hubble is in low-Earth orbit about 335 miles above Earth’s surface, actually less than 10 miles below most of the Starlink satellites. That means observatories and other orbiting space telescopes still face interference from satellite constellations. “Not only do you have to put telescopes in space, but you have to put them above all other vehicles,” Dr. McDowell said.
“I think we’re going to be forced to do this for decades to come,” he said. But that’s not possible with current low-Earth orbit telescopes or spacecraft the government is building and launching in the next few years.
To quantify the impact of satellite constellations on Hubble, astronomer Sandor Kruk of the Max Planck Institute for Extraterrestrial Physics in Germany and his colleagues analyzed an archive of images taken between 2002 and 2021.
They were helped by hundreds of citizen scientists who pored over the images to flag those with clear satellite streaks. This dataset was then used as a training set for a machine learning algorithm that analyzed more than 100,000 Hubble photos. Their results showed that from 2009 to 2020, the chance of seeing a satellite in Hubble images was only 3.7 percent. But the chance of seeing one in 2021 is 5.9% — an increase they say corresponds to Starlink. As of the date of the analysis, there were 1,562 Starlink satellites in orbit. Another company, OneWeb, has launched 320 satellites.
Mark McCaughrean, an astronomer at the European Space Agency and co-author of the new study, is confident in their analysis, but notes that it’s just a hiccup so far. Typically, Hubble takes multiple images stacked together — a technique that wipes out any satellites.
NASA agrees. “While such analysis may show a gradual increase in detected satellite tracks over time, most of these streaks are easily removed using standard data reduction techniques, and most of the affected images are still usable,” said a woman speaking People said of the latest research. “Satellite streaks do not currently pose a significant threat to Hubble’s scientific productivity and data analysis.”
This threat is heightened when Hubble surveys large swaths of the sky. Then it might just take an image or two before redirecting its camera. If satellite photos bombed one of the pictures, that picture might have to be discarded.
Additionally, satellites could pose a serious threat to telescopes that have not yet been launched. At the end of this year, China plans to send the China Sky Survey Space Telescope into low-Earth orbit. Xuntian will have a larger field of view than Hubble, making it harder for satellites to slip away undetected.
“It’s immediately heavily impacted by these satellites,” Dr McDowell said.
And Xuntian cannot simply be launched into a higher orbit. China’s plan is for the telescope to share orbit with the Tiangong space station so that astronauts can refurbish it if necessary.
A SpaceX spokesperson declined to comment on the new research, but pointed to the company’s past efforts to mitigate Starlink’s impact.The company has tried a number of methods to dim its satellites, including mirror film Designed to direct light away from the ground. But Meg Schwam, a planetary scientist at Queen’s University Belfast, who was not involved in the study, worries that the light would be directed upwards, which could make things worse for space-based telescopes.
There are too many unknowns right now, including the eventual number of satellites.
SpaceX hopes to eventually expand its fleet to 42,000 Starlink satellites. Many other companies are also on the market: Amazon, British satellite provider OneWeb, a Chinese company called Galaxy Space, and even the government.a combination 431,713 satellites It is planned to roll out in the next few years.
“It’s kind of crazy at the moment,” Dr. McCaughrean said.
This estimate is based on filings with the FCC and the International Telecommunication Union. But even with just 100,000 satellites launched, the number of satellites in orbit has increased by a factor of 10 since the new study—meaning roughly 50 percent of Hubble images will spot satellites. If every other image had satellite streaks, researchers worried about how much usable scientific data could be collected.
“When did Hubble cease to be useful?” Dr. McCawlane asked. “It might take 10 or 20 years, but it’s not inconceivable that you’d say, ‘Let’s stop bothering.'”
