One day soon, the night sky may look very different through a telescope. The rise of satellite megaconstellations—planned by Amazon, OneWeb, and Telesat, and now being actively implemented by SpaceX—may soon provide space-based internet service to the entire planet. However, these satellites have already begun to irreversibly damage observations of the night sky, and astronomers around the world are concerned that the problem may only worsen.
From May 2019 to January 2020, SpaceX placed 237 of its proprietary satellites into low earth orbit, making it the single largest satellite operator in the world. These satellites are part of a planned constellation called Starlink, which will comprise more than 12,000 mass-produced units, at altitudes from 210 mi to 710 mi above the ground. Starlink satellites are equipped with antennas that can provide 5G internet to millions of ground stations. This could radically alter the cost and availability of fast broadband in rural areas. Starlink plans to launch batches of 60 satellites every 2-3 weeks throughout 2020.
SpaceX satellites in its first four launches have surprised astronomers with their brightness. The night sky today is relatively uncrowded with artificial satellites, most of which are low in brightness, far away, and located in predictable orbits. Observatories have databases of all the satellites in the sky and are able to easily schedule their observations to avoid them. However, the SpaceX satellites are high in reflectivity and brightness, are placed in very low orbits, and are constantly adjusting their positions using artificial intelligence. This makes them nearly impossible to avoid.
The brightness of objects in the night sky is described by “magnitude.” The very brightest stars are magnitude -1. A person with sharp eyes can see magnitudes down to +8. A good pair of binoculars can see magnitudes down to +9 or so, and a modern observatory can see magnitudes down to +24.
The astronomical community, based on comments from SpaceX executives, expected Starlink satellites to be about +9 magnitude. This would make them invisible to the naked eye and within tolerances for modern telescopes’ noise filters. When the first batch of satellites was launched in May of last year, astronomers were shocked to realize that the satellites were many times brighter than expected, at magnitude +5. Starlink is visible to the naked eye and it can’t be avoided by the software available to modern observatories. Starlink units are brighter than 99% of all other satellites, and soon Starlink will comprise the majority of satellites in the sky.
The 237 current satellites have already ruined observations from telescopes in Chile, Hawaii, South Africa, Texas, and Arizona. Astronomers are up in arms: the Twitter account for Ohio State’s All-Sky Automated Survey for Supernovae, @SuperASAS-SN, tweeted, “Just imagine a private company being allowed to massively drill for oil in Yellowstone, purely for profit, destroying the park in the process. What #Starlink is doing is way worse - it pollutes the sky for EVERYBODY in the world, and you can’t escape it.”
SpaceX’s response has been minimal. SpaceX CEO Gwynne Shotwell has pleaded ignorance, saying, “We didn’t think of it. The astronomy community didn’t think of it.” However, predicting a satellite’s brightness is simple and can be calculated from the materials used to build it. Astronomers say that SpaceX either knew about the problem beforehand and kept it quiet, or didn’t undertake due diligence to find out whether their satellites would be an issue. SpaceX launched one satellite in 2019 with an experimental low-reflectivity coating, to see if it might help astronomers, but the company has not announced plans to launch any other satellites with this coating. Patricia Cooper, SpaceX’s Vice President of Satellite Government Affairs, told astronomers at the 235th meeting of the American Astronomical Society on January 8th that the company would continue launching the unmodified version of their satellite throughout this year, up to a constellation of 1,584 units.
Astrophysicist Rachel Paterno-Mahler tweeted, “SpaceX is giving lip service to wanting to work with astronomers, but actually doesn’t.” For now, government regulators seem equally unwilling to address issues with Starlink—the Federal Communications Commission (FCC) has already approved the constellation. With no specifications or regulations in place, scientists everywhere in the world are dependent on SpaceX to self-regulate. As astronomer Caitlin Casey put it, “The fact that one person, or one company, can take control and completely transform humans’ experience of the night sky, and not just humans, but every organism on Earth … that seems profoundly wrong.” For now, Starlink launches are set to continue indefinitely.