SpaceX became astronomers’ worst enemy when it started launching Starlink internet satellites.
But SpaceX worked with scientists to try to reduce the brightness of the satellites in telescope images.
Some of SpaceX’s solutions do work. Other mega-satellite companies, like Amazon’s, are taking notice.
NEW ORLEANS – When SpaceX launched its first Starlink satellites, astronomers around the world panicked and the company quickly became a villain of the skies.
“I felt that life as an astronomer and lover of the night sky would never be the same,” astronomer James Lowenthal told the newspaper. New York Times in 2019.
As the bright trail of satellites climbed through space and ascended to their target orbit in May 2019, people just standing outside could see them clear as day, flying overhead as they circled the Earth.
To some it seemed to herald the end of astronomy. “If there are a lot of bright moving objects in the sky, it makes our work very difficult,” Lowenthal told the Times.
But for rural populations, including in developing countries, who lack reliable internet, Starlink could make a huge difference as SpaceX aims to cover the Earth with high-speed broadband internet, courtesy of more than 10,000 satellites.
Nevertheless, Starlink satellites – now more than 5,000 strong – blast through astronomers’ eyes into the cosmos, ruining their data. Even some telescopes in space are not safe. Last year, a study found that about a third of Hubble Space Telescope images could be ruined by satellites by 2030.
SpaceX leads the way to change
SpaceX isn’t the only one doing this; it was only the first company to get massive quantities of bright spacecraft off the ground. At least a dozen companies, as well as the Chinese government, plan to launch their own mega-fleet of satellites.
Many astronomers view the burgeoning activities of Internet satellite constellations as an existential threat. But of all the companies rushing to claim this new frontier, SpaceX has calmed some of its critics by listening to them, working with them and trying to black out its satellites.
“Now we’re making progress,” Jonathan McDowell, an astronomer who has been one of Starlink’s most outspoken critics, told Business Insider at an American Astronomical Society conference in New Orleans.
McDowell and other astronomers met with satellite industry representatives to discuss efforts to keep the sky dark and radio silent.
No current SpaceX representatives participated in the session. Still, Starlink’s experimental solutions dominated the conversation — perhaps because it’s the only company that has tried the solutions astronomers have proposed.
“For me, the focus is not just on the call to sound the alarm, but on the path to coexistence,” Patricia Cooper, a satellite industry consultant and previously vice president of SpaceX’s satellite government affairs, told the assembled astronomers. “It’s no surprise that we haven’t solved the problem in four and a half years.”
SpaceX has tried black paint, sun visors, and now “mirror film.”
SpaceX has thrown a handful of spaghetti at the wall to dim the shine on its satellites, and a few things have stuck.
In 2020, about six months after that first bright Starlink trail glided across the sky, SpaceX threw its first noodle on the problem by essentially painting some satellites black.
That kind of helped. The satellites were less bright, but still too bright.
Later that year, SpaceX tried using sun visors to prevent sunlight from hitting the undersides of the satellites, where it could reflect back to Earth and make them appear bright.
That worked. The satellites with sights were about one-third as bright as those launched without sights. But they were still bright enough to mess with astronomers’ data. The sights were a fixture on many Starlink satellites until SpaceX added laser communications. The sights were blocking the lasers, so they had to go.
Now SpaceX is exploring a “mirror film” that could further reduce the brightness of the next generation of Starlink. However, those satellites are much larger than the old ones, “so they kind of fade away,” McDowell said.
“I don’t think there’s any villain or hero stuff here,” he added.
SpaceX developed its solutions through meetings with astronomers, including the world’s first satellite brightness conference. In 2022, the International Astronomical Union formalized this ongoing collaboration as the Center for the Protection of Dark and Silent Skies from Interference from Satellite Constellations – CPS for short.
SpaceX has even adopted an operational adjustment that astronomers suggested: pointing the satellites’ solar panels away from the sun when they cross the line between day and night. That’s when they appear on the horizon and are most damaging to telescopes on Earth. Giving the solar panels less sunlight at this time helps astronomers, but means less energy for the satellite.
“That’s a real, substantial mitigation that they’ve done,” McDowell said. “They’re really making money from it, so we appreciate that.”
“Whether the other companies will do so remains to be seen,” he added.
Amazon and other companies can follow SpaceX’s lead
Amazon and a small Earth imaging company called Planet Labs are both following SpaceX’s lead.
Chris Hofer, international team leader for Amazon’s Project Kuiper internet satellites, told the New Orleans astronomers that SpaceX’s Starlink tinkering has been helpful.
Since joining CPS, Hofer said Amazon has started improving its solar panels and exploring sunshades.
Both Hofer and Kristina Barkume, of the terrestrial satellite company Planet, said they would watch SpaceX’s new mirror film tests with interest.
“These innovations are helping us,” Barkume told Business Insider.
While a few companies seem to be paying lip service to the bright satellite problem, or even willing to spend money on it, it is unlikely to go away.
Tens of thousands of satellites could be in Earth’s orbit in the coming years. No matter how bright they are or not, they will almost certainly disrupt astronomy. Scientists will have to find ways to peek through the gaps between satellites, no matter how small or fleeting those windows to the cosmos become.
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