Mission in space is to save the night sky

It looked like a scene from a sci-fi blockbuster: an astronomer in the Netherlands captured footage of a train of brightly-lit SpaceX satellites ascending through the night sky, stunning space enthusiasts.

Issam Ahmed

Thursday, June 06, 2019

It looked like a scene from a sci-fi blockbuster: an astronomer in the Netherlands captured footage of a train of brightly-lit SpaceX satellites ascending through the night sky, stunning space enthusiasts.

But the sight has also provoked an outcry among astronomers who say the constellation, which so far consists of 60 broadband-beaming satellites but could one day grow to as many as 12,000, may threaten our view of the cosmos and deal a blow to scientific discovery.

The launch was tracked around the world, and it soon became clear the satellites were visible to the naked eye: a new headache for researchers who already have to find workarounds to deal with objects cluttering their images of deep space.

"People were making extrapolations that if many of the satellites in these new mega-constellations had that kind of steady brightness, then in 20 years or less, for a good part the night anywhere in the world, the human eye would see more satellites than stars," says Bill Keel, an astronomer at the University of Alabama.

The satellites' brightness has since diminished as their orientation has stabilized and they have continued their ascent to their final orbit at an altitude of 550 kilometers.

But that has not allayed the concerns of scientists entirely. For they are worried about what happens next.

Elon Musk's SpaceX is just one of a several companies looking to enter the fledgling space internet sector.

To put that into context, there are currently 2,100 active satellites, according to the Satellite Industry Association.

If another 12,000 are added by SpaceX alone, "it will be hundreds above the horizon at any given time," says Jonathan McDowell of the Harvard Smithsonian Center for Astrophysics. And the problem would be exacerbated at certain times of the year and certain points in a night.

"So it'll certainly be dramatic in the night sky if you're far away from the city and you have a nice, dark area," McDowell says. "And it'll definitely cause problems for some kinds of professional astronomical observation."

The mercurial Musk responded to the debate on Twitter with contradictory messages, pledging to look into ways to reduce the satellites' reflectivity but also saying they would have "zero percent impact on advancements in astronomy" and that telescopes should be moved into space anyway.

He also argued that the work of giving "billions of economically disadvantaged people" high-speed internet access through his network "is the greater good."

Keel says he is happy that Musk has offered to look at ways to reduce the reflectivity of future satellites but questions why the issue has not been addressed previously.

If optical astronomers are concerned, then their radio astronomy colleagues, who rely on the electromagnetic waves emitted by celestial objects to examine phenomena such as the first image of the black hole discovered last month, are "in near despair," he adds.

Satellite operators are notorious for not doing enough to shield their "side emissions," which can interfere with the observation bands that radio astronomers are looking out for.

"There's every reason to join our radio astronomy colleagues in calling for a 'before' response," says Keel.

"It's not just safeguarding our professional interests but, as far as possible, protecting the night sky for humanity."

AGENCE FRANCE-PRESSE