SpaceX uses Falcon 9 rockets to transport batches of around 60 Starlink satellites at a time.
Paul Hennessy/SOPA Images/LightRocket via Getty Images
SpaceX became astronomers’ greatest enemy when it started launching Starlink internet satellites.But SpaceX worked with scientists to try reducing the satellites’ brightness in telescope images.Some of SpaceX’s solutions sort of work. Other mega-satellite ventures, like Amazon’s, are noticing.
NEW ORLEANS — When SpaceX launched its first Starlink satellites, astronomers all over the world freaked out and the company quickly became a villain of the skies.
“I felt as if life as an astronomer and a lover of the night sky would never be the same,” astronomer James Lowenthal told the New York Times in 2019.
As the bright trail of satellites climbed through space, ascending to their target orbit in May 2019, people just standing outside could see them clear as day, zipping overhead as they circled Earth.
To some, it seemed to herald the end of astronomy. “If there are lots and lots of bright moving objects in the sky, it tremendously complicates our job,” Lowenthal told the Times.
But for rural populations, including in developing countries, that lack reliable internet, Starlink could make a huge difference since SpaceX aims to blanket the Earth in high-speed broadband internet, courtesy of more than 10,000 satellites.
Nonetheless, Starlink satellites — now more than 5,000 strong — are streaking across astronomers’ views of the cosmos, ruining their data. Even some telescopes in space aren’t safe. Just last year a study found that about one-third of the Hubble Space Telescope’s images could be ruined by satellites by 2030.
SpaceX leads the way for change
A satellite trail streaks in front of galaxies in this image from the Hubble Space Telescope.
NASA/ESA/Kruk et al.
SpaceX isn’t alone in this endeavor; it was just the first company to get huge batches of bright spacecraft off the ground. At least a dozen companies, as well as the Chinese government, are planning to launch their own mega-fleets of satellites.
Many astronomers view the budding business of internet-satellite constellations as an existential threat. But of all the companies racing to claim this new frontier, SpaceX has calmed some of its critics by listening to them, working with them, and trying to darken its satellites.
“Now we’re making progress,” Jonathan McDowell, an astronomer who has been one of the most outspoken of Starlink’s critics, told Business Insider at a conference of the American Astronomical Society in New Orleans.
Three different satellite trails outshine the stars in an image from the Hubble Space Telescope.
NASA/ESA/Kruk et al.
McDowell and other astronomers were meeting with representatives from the satellite industry to discuss efforts to keep the skies dark and radio-quiet.
No current SpaceX representative participated in the session. Still, Starlink’s experimental solutions dominated the conversation — maybe because it’s the only company that’s been trying the fixes astronomers have suggested.
“For me the focus is not on the call to alarm only, it’s on the path to coexistence,” Patricia Cooper, a satellite-industry consultant who was formerly VP of SpaceX’s government affairs for satellites, told the assembled astronomers. “Not surprisingly, we didn’t solve the problem in four and a half years.”
SpaceX has tried black paint, sun visors, and now ‘mirror film’
CEO Elon Musk has said little publicly about astronomers’ concerns, but SpaceX has worked with astronomy leaders privately.
Slaven Vlasic/Getty Images
SpaceX has thrown a handful of spaghetti at the wall to dim its satellites’ shine, and a few things have stuck.
In 2020, about six months after that first bright Starlink trail glided through the skies, SpaceX lobbed its first noodle at the problem by essentially painting a bunch of the satellites black.
That sort of helped. The satellites were less bright, but they were still too bright.
Later that year, SpaceX tried using sun visors to block sunlight from hitting the bottom side of the satellites, where it can reflect back to Earth and make them appear bright.
That worked. The visored satellites were about one-third as bright as those that launched without visors. But they were still bright enough to mess with astronomers’ data. The visors were a regular feature for many Starlink satellites until SpaceX added laser communications. The visors blocked the lasers, so they had to go.
Now SpaceX is looking into a “mirror film” that could further reduce brightness on its next Starlink generation. However, those satellites are much bigger than the old ones, “so it kind of cancels out,” McDowell said.
“I don’t think there are all villain or all hero things here,” he added.
SpaceX developed its solutions through meetings with astronomers, including the world’s first conference on satellite brightness. In 2022, the International Astronomical Union formalized this ongoing collaboration as the Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference — CPS, for short.
SpaceX has even adopted an operational tweak that astronomers suggested — pointing the satellites’ solar panels away from the sun as they pass over the line between night and day. That’s when they appear on the horizon, and are most detrimental for telescopes on Earth. Giving the solar panels less sun at this time helps astronomers, but means less energy for the satellite.
“That’s real, substantial mitigation that they’ve done,” McDowell said. “They’re really taking a money hit by doing that. So we appreciate that.”
“If the other companies will do it remains to be seen,” he added.
Amazon and other companies may follow SpaceX’s lead
Amazon and a small Earth-imaging company called Planet Labs are both following SpaceX’s lead.
Chris Hofer, international team lead for Amazon’s Project Kuiper internet satellites, told the astronomers in New Orleans that SpaceX’s Starlink tinkering has been helpful.
Since joining CPS, Hofer said Amazon has begun improving its solar panels and looking into sun shades.
Both Hofer and Kristina Barkume, of the Earth-imaging satellite company Planet, said they would be following SpaceX’s new mirror-film tests with interest.
“Those innovations help us,” Barkume told Business Insider.
Though a few companies seem to be paying lip service to, or even throwing money at, the bright-satellite problem, it probably won’t go away.
The coming years could see tens of thousands of satellites crowding Earth’s orbit. No matter how bright they are or aren’t, they will almost certainly interfere with astronomy. Scientists will have to find ways to peep through the gaps between the satellites, however small or fleeting those windows to the cosmos become.