Photos from SpaceX’s satellite launch shocked many astronomists, who are worried about their ability to study deep space.
Space observers eagerly watched last week as SpaceX launched the first round of what it says will be thousands of satellites meant to deliver fast and affordable internet to Earth.
Many were surprised at what they saw.
The first 60 of nearly 12,000 planned satellites in the Starlink project visibly lit up the sky as they travelled in a line in low-Earth orbit.
Videos of the satellites began circulating on social media, sparking alarm among astronomers who need a clear view of the sky to study deep space and already report having problems with the roughly 5,000 satellites currently in orbit.
Telescopes aimed at examining a large portion of the sky require a long exposure time. The larger the field of view, the longer the imaging will take and the more likely the picture will be littered with trails from satellites moving across the sky.
“My experience has been that even now … a significant number of the exposures you take will have a satellite streak going through,” says Phil Mauskopf, a professor at Arizona State University’s School of Earth and Space Exploration.
“I don’t think [Starlink is] going to completely ruin astronomy,” Mauskopf says. “I think you’ll still be able to do it, but I do think it will make it less efficient.”
While satellite visibility poses its own problems, another issue that we can’t see worries astronomers.
Satellites work by using radio waves to send data back to Earth. That means they produce radio frequency interference, says Caitlin Casey, an assistant professor in the University of Texas at Austin’s astronomy department.
Photos: Space Over Time
Many devices produce radio frequency interference, or RFI, Casey says. Cellphones, the radio we listen to and military communications networks are all sources.
The difference is that these devices are land-based, and Starlink’s satellites will be directly between telescopes and the distance objects astronomers want to study.
“For reference, even a single cell phone located on the surface of the moon would appear like a bright radio source contaminating the sky in its vicinity,” Casey says in an email.
Astronomers are able to study the history of the universe by examining distant gases. If the RFI gets to be too much, “it’ll potentially close our window on these critical measurements of gas in the early Universe,” she says.
When U.S. News reached out to SpaceX for comment, a company spokesperson passed along links to Elon Musk’s tweets on the topic.
The SpaceX CEO’s remarks ranged from dismissive to promising.
In response to concerns about the project, Musk tweeted that “potentially helping billions of economically disadvantaged people is the greater good” and that “we need to move telescopes into orbit anyway.”
But he also said that the project will avoid certain radio frequencies specifically for radio astronomy.
Without giving many details, Musk said “we’ll make sure Starlink has no material effect on discoveries in astronomy.”
Casey says astronomers are likely appreciative that SpaceX is listening to their concerns but adds that it shouldn’t be up to the good will of one company to protect scientific research. She says an independent assessment of the project’s impacts is needed.
Many astronomers agree that communication from SpaceX about the project was lacking.
“It seems like a problem to me that most astronomers have found out about the impact of this project through Twitter on a holiday weekend,” Casey says.
Mauskopf suggests that SpaceX look into coordinating with large telescope projects to see if it would be possible to shut off the satellites as they fly over certain areas.
“If they can’t do that, they’ll blast us,” he says.
At least one satellite doesn’t expect Starlink to pose too much of a problem.
The Large Synoptic Survey Telescope, which is being built in Chile, is meant to conduct a 10-year survey of the sky to help understand topics like dark matter and the formation of our galaxy.
An increase in the number of satellites will require some extra work from the telescope’s team, but it won’t be “catastrophic,” says Yusra AlSayyad, the telescope team’s satellite trail expert.
Once the team has completed several regional surveys, an algorithm will be able to anticipate and remove satellite trails, AlSayyad says.
Beyond Starlink, concerns are rising over the effects the intensifying satellite presence in Earth’s atmosphere might have.
One factor that is particularly concerning to stargazers is that SpaceX’s satellites are being launched into low orbit, which will help them to provide faster internet access, according to Musk. But being closer to the ground means being more visible, and several companies, including Amazon and OneWeb, have similar plans to launch more satellites to provide internet coverage.
“The number of low Earth orbit satellites planned to launch in the next half-decade has the
potential to fundamentally shift the nature of our experience of the night sky,” the International Dark-Sky Association said in a statement.
The group, which was founded in 1988 by astronomers concerned about the growing prevalence of light pollution, asked “all parties to take precautionary efforts to protect the unaltered nighttime environment before deployment of new, large-scale satellite groups.”
Caution in this area should be used since the effects aren’t fully known, it said.
“We do not yet understand the impact of hundreds or thousands of these visible satellites scattered across the night sky on nocturnal wildlife, human heritage, or our collective ability to study the cosmos,” the association said.