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Starlink: light pollution from SpaceX satellites


Light pollution from SpaceX satellites is a disaster for astronomers

These new satellites, called Starlink, are expected to provide broadband Internet access. But their proliferation complicates or even prevents the work of astronomers.

The new Starlink satellites, a project of the American company SpaceX, directed by Elon Musk, are expected to provide high-speed Internet access to places where it is unreliable, expensive, or completely unavailable.

The operating principle of Starlink is to have permanently over our heads dozens or even hundreds of satellites that can take over Internet connections and send them from one to the other satellite so that we have a fluid observation on the Internet “Explains Guillaume Cannat, author of The Sky Guide.

“In a few years, we could end up with 10, 20, 30 or 40,000 satellites”

As of May 1, 2020, 422 satellites of SpaceX were already in orbit. SpaceX plans to multiply their number by 30. ” The Starlink project is a project that was launched a few years ago, but the first satellites were launched into space last year, in May 2019. Since then, there have been almost 400 satellites that have been launched , 420 at last count “Says Guillaume Cannat.

And thousands more are coming. “By the end of 2020, we could have more than 1,000 satellites in orbit. By 2025, up to 12,000 satellites, ”notes Guillaume Cannat. What’s more, SpaceX is far from the only company wanting to send its satellites. ” There are other projects from other companies that are planning thousands of other satellites. Ultimately, in a few years, we could end up with 10, 20, 30 or 40,000 satellites devoted to high-speed Internet connection all over the planet.

“What astronomers fear most is the brightness of the satellites”

This multiplication of objects in orbit around the planet worries many astronomers. 1,900 of them signed a petition to oppose the project. ” What astronomers fear most is their brightness, explains Jonathan McDowell, astrophysicist at the Harvard-Smithsonian Center for Astrophysics. These satellites are quite large and are in a very low orbit. These two factors combined make them so bright that they can be seen by people from the ground. * ”

The consequences are problematic, according to Jonathan McDowell: ” When a satellite passes in front of a camera during a shooting, it collaterally damages the collected data. And it also has an implication for ordinary people who like to look at the starry sky to observe the constellations if the sky is filled with moving objects.

“It will become almost impossible to make quality astrophysical observations”

Ultimately, some astronomers fear that they will no longer be able to do their work from the ground. ” As long as there are a few satellites, that’s fine, but when there are thousands, if not tens of thousands, of satellites in orbit above our heads, permanently, it will become almost impossible to make quality astrophysical observations “, Guillaume Cannat warns.

For its part, the SpaceX company defends itself. ” There are already 4,900 satellites in orbit, which people notice 0% of the time. Starlink will not be seen by anyone, unless looking very carefully, and will have a 0% impact on the progress of astronomy Assures the company. A misleading statement for Jonathan McDowell. ” Yes, there are dozens of satellites in orbit, but most of them are small or have very high orbits. So you can’t see them. SpaceX’s satellites are big and low, so much brighter than the 4,000 or so satellites it talks about Argues the astrophysicist.

SpaceX tries to reassure

Faced with scientists’ fears, the founder of SpaceX tried to reassure him by saying that he was going to adapt his technology in order to reduce its impact. He also organized several commissions to discuss with astronomers possible solutions.

Good first steps from Jonathan McDowell. ” SpaceX launched “Dark Sat”. One of the Starlink satellites has been painted with a special layer on the side to make it less bright. It works a little. They are now planning to launch a new test satellite called “Visor Sat” which will have a sort of sun visor around it to reduce the radiation from the antennas.

Risk of collision

But astronomers have another concern: the risk of collision. ” You have all these satellites going in completely different directions and tens of thousands of km per hour. Suppose you think one satellite is going to hit another. You move it, but before that, you have to be sure where you move it to be sure it won’t hit another satellite. And if all the satellites are moved around constantly to avoid each other, it will become an extremely difficult problem Says Jonathan McDowell.

On September 2, 2019, the European satellite Aeolus had to perform a maneuver to avoid a collision with one of the first Starlink satellites. With the proliferation of objects in orbit, some astronomers even fear the possibility of a chain reaction called Kessler syndrome: when two satellites collide, the debris of the collision will themselves collide with other satellites.

SpaceX has submitted a request to send 30,000 additional satellites

All those billions of dollars invested in advanced electronics orbiting the Earth could turn into shrapnel, like the ring of Saturn. And you could no longer use the space. This is the nightmare scenario “Imagines Jonathan McDowell. He tempered, however: ” I’m a little less worried after learning about Starlink’s new plan, because their satellites are low enough that most of the collision debris should fall relatively quickly.

In addition to the 12,000 satellites already planned, SpaceX has made a request to send 30,000 additional satellites, which could increase their number to 42,000. An even greater threat to scientists, who could see their work become more complicated in the years to come.

One of the most impacted areas of astrophysics is the search for asteroids

The contribution of astrophysics to understanding our own planet is considerable. A lot of the previous work on climate change has been done by studying the atmosphere of other planets to finally realize: “Oh, we don’t want our planet to become like this.” And, you know, one of the areas of astrophysics potentially among the most impacted by Starlink satellites is the search for asteroids that could hit Earth. So we really don’t want to miss any of them “Alerts Jonathan McDowell.

What I hope is thatElon Musk and the company SpaceX and the companies that have projects like that in mind, put a downside. What would be important first of all is that there is an organism at the level of the whole planet which manages the possibilities of putting into orbit of satellites by private companies. Right now, private companies are doing what they want, it’s the Wild West “Deplores Guillaume Cannat.

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