How SpaceX Is Pacifying Astronomer’s Anger?
Astronomers are not happy with SpaceX, their Starlink satellites are ruining night sky
On Thursday, March 4th, 2021, another SpaceX Falcon 9 blasted off from Kennedy Space Center, carrying another 60 Starlink internet communications satellites, bringing the full size of the constellation to around 1000.
They’re planning to do these launches every couple of weeks during 2021, bringing the total number of satellites in the constellation to about 1440, which is enough to provide high-speed internet services to the United States and parts of Canada.
Shortly after launch, because the satellites are raising their altitude, they’re clearly visible as they streak across the sky in a close train. One of the big topics at last year’s meeting of the American Astronomical Society in Honolulu, Hawaii, was the impact of Starlink and the other upcoming internet constellations on astronomy.
Astronomers already have to deal with satellites photo bombing their photographs of space, but it surprised them at just how bright the Starlinks were. There are about 18,000 satellites and pieces of space junk flying overhead that are being constantly monitored and reflect a significant amount of sunlight.
Right now there are only about 200 satellites and pieces of space debris visible with the unaided eye. During an average night, 600–700 satellites pass overhead any spot on Earth from astronomical sunset to astronomical sunrise, when telescopes are doing their science.
During the winter, when the nights are long, the satellites are only visible shortly after sunset, and right before sunrise at low angles which aren’t great for observing. But during the summer, with its shorter nights and higher angle of sunlight, some observatories can see satellites pass through their field of view all night long.
People get this in Canada during the summer when the International Space Station will pass right overhead, and then 90 minutes later, do it again. It’s exciting the first few times, and then it becomes a pain to remove from your astrophotos.
The Starlink satellites fly at 550 kilometers, low enough that they limit their visibility to the beginning and end of the night for most of the year. According to astronomers at the AAS meeting, they’re brighter than 99% of the objects in orbit, reaching 5th magnitude — or just visible with the unaided eye — with no kind of brightness mitigation.
More worrying, though, could be future satellite constellations. Starlink has around 1000 satellites today, but they’ve applied for permission to fly 42,000 satellites, starting with 12,000 over the next 8 years, which means they’ll have 5 times the number of satellites launched by the rest of humanity combined.
Another satellite company, One Web, has already launched a handful of their internet satellites as well, and these fly at an altitude of 1,200 kilometers. This means that they’re fully visible to their entire flight overhead, although they’re less bright, seen at only 8th magnitude.
That’s still bright enough to leave a bright streak through powerful observatories. Amazon has filed for its satellite internet service, proposing over 3,000 which will fly at 590, 610, and 630 kilometers.
Higher than Starlink and so visible for longer. Perhaps the greatest worry is the new all-sky survey telescopes like the Vera Rubin Observatory (previously known as the Large Synoptic Survey Telescope). This instrument continuously scans the skies, night after night, helping astronomers find asteroids, comets, new supernovae, and really anything that changes from night to night.
The Vera Rubin Observatory has such a wide field of view and takes so many images that there will be multiple Starlink passes in every photograph. According to one astronomer, the satellites could provide a similar profile to galaxies in brightness. So, be prepared for galaxies appearing and disappearing in your data.
Even more worrisome could be their impact on radio telescopes, which have already gotten overwhelmed by broadcast satellites. Catching a powerful transmission from a satellite can completely burn out a radio telescope receiver.
What can astronomers do to deal with this? And what are satellite companies doing to minimize their impact on astronomy? Patricia Cooper, SpaceX’s vice president of satellite government affairs, was at the AAS meeting and presented SpaceX’s perspective on the situation. She outlined the company’s short-term plans to build the constellation, but also how they’re going to mitigate the impact of the satellites on science and astronomy.
Like astronomers, it surprised SpaceX at how bright they see the satellites from Earth. When they first launch, the satellites are easy to see with the unaided eye. According to Cooper, this is because the satellites open their solar panel in a configuration that reduces drag.
Once they reach their operational altitude, they change their angle, making them invisible without a telescope or binoculars. To decrease the brightness, they tried a few methods of darkening one satellite in the most recent launch of 60. It’s too early to know if their techniques were successful, though.
This is going to be an ongoing process, with astronomers giving feedback to Starlink with each test. Until they can settle on the most effective method, most Starlinks will fly with no darkening strategy. And they’ll stay in space for about 5 years until they de-orbit.
The downside of painting the satellites black is that it changes their profile in the infrared spectrum. What makes them less visible in some telescopes could make them much brighter in infrared observatories. It’ll probably end up being a compromise. SpaceX is also providing real-time tracking information for all the satellites to other companies and telescope operators.
This will help reduce the chances of an impact and give astronomers a warning when a Starlink could pass through the field of view and saturate their detectors. They could program telescopes to automatically avoid observing regions of the sky where Starlinks are anticipated to pass through.
SpaceX is releasing launch trajectory information for new batches of satellites, to help astronomers observe around the times when the bright launch train might fly through their field of view. Although astronomers are very frustrated with Starlink and the age of global satellite constellations, it pleased them that SpaceX is working with them to mitigate the impact.
Because regulators have already approved the satellite launches, astronomers can’t rely on new laws, they’ve got to work with SpaceX to lower the brightness of Starlink. Astronomers have already had 6 meetings with SpaceX to figure out a strategy, and they’ve described the company as open and responsive to their suggestions to mitigate brightness.
Elon Musk, in the recent podcast with Joe Rogan, has said that Starlink satellites will not be an obstruction for astronomers. Satellite is only visible when they are launched into the orbit, when they get into the orbit, they become invisible. Many people have suggested in the past, and I’m sure I’ll get it in the comments here too.
Why don’t astronomers just switch to space telescopes instead? The reality is that ground-based astronomy is still a bedrock of science, even with lowering rocket costs. A modern ground-based observatory with adaptive optics can reduce the impact of the Earth’s atmosphere as if the telescope was in space. Ground-based observatories can be easily built, upgraded, and adapted with new science instruments.
Astronomy from the surface of the Earth is going to be vital for decades. But with all this impact on astronomy, humanity is going to connect to the internet. And that’s because you’re wealthy enough, or in a densely populated enough area, that it’s workable for an internet service provider to connect you to the internet.
Starlink aims at providing low latency high-speed internet at a low cost. Internet through Starlink satellites will work better in low and moderately populated areas. People in the densely populated areas will still have to depend on the 5G towers for high-speed internet. People can do their banking, shopping, educate themselves and search for jobs.
These satellites will open a plethora of opportunities for people, especially in rural areas. There are 5 million cell phone towers worldwide, and it’ll take many, many more to go the last mile and connect the rest. Think of how much of an eyesore these towers already are. Consider about thousands of kilometers of ditches dug for fiber optics, or underwater cables running through sensitive marine environments.
Think about the impact on radio telescopes when there are powerful 5G antennae blanketing every corner of the Earth. Satellite internet is probably the only way to bring the rest of humanity online without a significant impact on the environment.
It’s too bad that more time wasn’t taken to reduce the impact on science and astronomy, but this revolution in communication is inevitable. The only way to know if it was worth it will depend on whether it was a benefit to society. Did it allow billions of people to join the global online community at an affordable price, or did it only allow stockbrokers a way to shave a few nanoseconds off their trades? We’re just going to wait and find out. What do you think? Let me know your thoughts in the comments.