Satellites keep bombarding the Hubble Telescope with light, and it’s getting worse

It’s becoming more difficult for the Hubble Telescope and other Earth-orbiting telescopes to capture pristine images thanks to the surge in satellite launches. Satellite paths could corrupt nearly 40% of the images taken by the Hubble Telescope, and up to 96% of those taken by three other telescopes over the next decade, according to a new study. He studies By NASA researchers published today in the journal nature.

They warn that this could jeopardize scientists’ ability to detect asteroids of concern or discover new planets. Our view of space is getting murkier without efforts to reduce light pollution from massive new constellations of satellites.

“I’ve focused my career on trying to make telescopes see better… Try to make telescopes more sensitive, more precise, and get better images,” says Alejandro Burlau, a research scientist at NASA and lead author of the study. “For the first time, we have found something that could be worse in the future.”

The scale of the problem is staggering. Cheap launch costs and the proliferation of communications satellites such as Starlink’s have opened a Pandora’s box of new challenges in space. Satellite tracks, which look like streaks of light, have already been detected in 4.3% of images taken by Hubble between 2018 and 2021. The number of satellites orbiting the Earth has increased 5000 in 2019 to more than 15,800 today, According to the European Space Agency. This number could reach 560,000 if currently planned satellite launches continue over the next ten years or so.

Borlauf and his colleagues simulated the view that four telescopes would likely have after all these launches. With so much crowding in space, they expect Hubble to be able to unintentionally capture an average of 2.14 satellites per exposure. China’s Xuntian Space Station Telescope, one of the other telescopes included in the study and expected to launch next year, can see an average of 92 satellites per exposure. Hubble is unlikely to capture a large number of satellites in its images because of its narrow field of view. Fortunately, other powerful telescopes, including… James Webborbited far enough from Earth to avoid light pollution from satellites.

The problem goes beyond simply including a satellite (or several) among the visions of swirling nebulae, stars and distant planets captured by these telescopes. Satellites reflect light from the sun, moon or Earth, which can be bright enough to obscure details that would have been captured in the image if it were not for light pollution. Borlauf explains that researchers may not be able to detect a change in the star’s brightness that might indicate the presence of an exoplanet there. “You will lose this information because a satellite passes in front of you.”

He says it’s time to find solutions, before there are too many satellites in orbit. Efforts to design darker, less reflective satellites have presented new problems because they tend to become hotter and shed more infrared light as a result. The researchers also tried to devise a strategy to capture images at times and locations when satellites were least likely to cross their path, an endeavor that becomes more difficult to undertake as congestion increases. It will require more coordination on the ground with companies and governments launching satellites, perhaps by placing them in an orbit lower than where telescopes are located to avoid obstructing their view or regulating where they can be deployed.

“There has to be an ideal way to place space constellations and telescopes… so that we can coexist in a sustainable way,” Borlauf says.