The Hubble and other Earth-orbiting telescopes are increasingly challenged to obtain clear images due to the recent uptick in satellite launches. According to a study released today in the journal Nature by NASA researchers, satellite trails could harm nearly 40 percent of the images captured by the Hubble and up to 96 percent of those from three other telescopes over the next ten years.
They caution that this could threaten researchers’ capacity to identify troubling asteroids or unearth new planets. Without addressing the light pollution generated by new megaconstellations of satellites, our cosmic perspective will continue to deteriorate.
“My work has been dedicated to enhancing telescope vision … aiming to make them more sensitive and precise for improved imaging,” states Alejandro Borlaff, a NASA research scientist and primary author of the study. “For the very first time, we’ve encountered something that might indeed worsen in the future.”
The magnitude of this issue is staggering. Reduced launch expenses and the expansion of communication satellites like Starlink’s have introduced a multitude of new challenges. Satellite trails, which appear as light streaks, were already observed in 4.3 percent of Hubble images from 2018 to 2021. The number of satellites in orbit has escalated from 5,000 in 2019 to over 15,800 currently, per the European Space Agency. This figure could surge to 560,000 if the planned satellite launches occur over the following decade.
Borlaff and his team simulated the anticipated views from four telescopes after these numerous launches. They predict that the Hubble might inadvertently capture an average of 2.14 satellites with each exposure. The Chinese Space Station Telescope Xuntian, included in the study and projected to launch next year, could capture an average of 92 satellites per exposure. The Hubble is less probable to capture as many satellites in its images due to its more restricted field of view. Luckily, other advanced telescopes, such as the James Webb, are positioned at a sufficient distance from Earth to escape light interference from satellites.
The challenge extends beyond the accidental inclusion of a satellite (or several) among the images of swirling nebulae, stars, and far-off planets that these telescopes generate. The satellites reflect sunlight, moonlight, or terrestrial light, which can be intense enough to mask details that might otherwise appear in an image were it not for that light pollution. Researchers may struggle to notice a variance in a star’s brightness that could suggest the presence of an exoplanet, Borlaff clarifies. “You will lose that information because a satellite passed in front of you.”
Now is the time to seek solutions, he emphasizes, before the satellite count in orbit becomes overwhelming. Endeavors to create less reflective and darker satellites have introduced new complexities because they often heat up and emit increased infrared light as a result. Researchers have also experimented with timing their image captures to reduce chances of satellite interference, a task that becomes increasingly challenging as congestion in space grows. It requires better coordination with companies and governments launching satellites, possibly positioning them in lower orbits than the telescopes to prevent obstructing their sight or setting regulations on their deployment.
“We need an optimal strategy for the placement of satellite constellations and space telescopes … so that we can coexist sustainably,” Borlaff asserts.
