02/10/2020

Huge constellations of satellites like SpaceX’s Starlink could make ground-based astronomy impossible, and we’re running out of time to deal with the problem

By Leah Crane
The launch of a batch of SpaceX’s Starlink satellites
SpaceX photos
On 6 January, SpaceX launched 60 Starlink communications satellites into orbit. This brings the number of Starlink satellites in orbit now up to 180, part of a planned fleet of as many as 42,000 spacecraft that SpaceX CEO Elon Musk says will bring internet to underserved areas of the world. But they might also cause problems for astronomy.
The satellites show up as a line of bright dots gliding across the night sky. They are visible to the naked eye in the weeks after launch and slowly become dimmer as they enter orbits farther into space. Then, theyre mostly too dim for our eyes to spot them, but telescopes still can.
When the satellites pass through a telescopes field of view, they create bright streaks that cut through images of the sky, obscuring anything that might be behind them and pouring so much light into the telescope that it renders some observations completely unusable.
What surprised everyone the astronomy community and SpaceX was how bright the satellites are, said Patrick Seitzer at the University of Michigan during a panel discussion on satellite mega-constellations at a meeting of the American Astronomical Society (AAS) in Hawaii on 8 January. SpaceX representatives declined to participate in the discussion, according to AAS press officer Rick Fienberg.
In an effort to assuage astronomers, SpaceX is testing one satellite thats a bit different from the others. This one was included in the most recent launch and is partially coated in a dark material to make it less shiny and visible in telescope images. We dont have any data yet on how well its working.
Jeffrey Hall at Lowell Observatory in Arizona said that SpaceX has been cooperative in communicating with astronomers through a AAS committee, but they have not yet figured out a solution. In the early stages were really trying to understand to what level is this a nuisance and to what level it is an existential threat to ground-based astronomy, he said.
The problem for astronomers doesnt end with SpaceX several other companies are working on these mega-constellations of satellites. Blue Origin, OneWeb, and Amazon all have plans to launch thousands of communications satellites in the coming years.
SpaceX has started launching before the law has had a chance to catch up, and once the satellites are in space there’s no backtracking. While the company does need approval from regulatory bodies for each launch, theres no regulation preventing SpaceX from launching an unlimited amount of satellites, which would be the death knell for ground-based astronomy.
Regulation of the wild west up there is necessary, said Hall. That is going to take a great deal of time to implement just because of the nature of that beast. At this point, he said, we have to rely on firms like SpaceX to voluntarily cooperate with astronomers to attempt to keep the impacts of their satellite constellations as low as possible.
With more than 1500 Starlink satellites slated for launch in 2020, that cooperation will need to be speedy if its going to make any difference. [Starlink is] just the start, said Seitzer. We have a very short time to deal with this issue before the sky is overwhelmed with bright satellites.
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