General, Research, Technology

Why did Starlink satellites become invisible to the human eye?

Over the past two years, SpaceX has sentspace of more than 950 Starlink satellites. But in the future, it intends to send 12,000 objects to earth orbit, and for this it already has permission from the Federal Communications Commission (FCC). The company floods the near-earth space with satellites for good purposes, because it wants to provide Internet to even the most remote places on our planet. In 2020, Starlink satellite Internet began working in test mode and the first users have already shared their reviews. But astronomers are far from happy with launched satellites, because they reflect sunlight and prevent them from studying distant objects in space. And if there are even more satellites, researchers can miss the approach of a dangerous asteroid, which is fraught with a worldwide catastrophe. But recently, Starlink satellites have begun to reflect less light and are almost invisible to the naked eye. What happened?

Starlink satellites in the skies of the Netherlands in May 2019

New Starlink satellites

SpaceX has long been aware thatastronomers complain about its satellites. To reduce reflections from satellites, in early summer 2020, new models were launched into Earth's orbit, equipped with protective visors. The new type of satellites was named VisorSat and their beauty lies in the fact that the visors do not allow the sun rays falling on them to be strongly reflected. At first, the idea of ​​the company seemed dubious, but in the end it proved to be effective. The reflectivity of satellites is called albedo and recently scientists have found that after the installation of protective visors, this figure has dropped markedly.

VisorSat design diagram

The scientific publication shared good newsScience Alert citing Business Insider. The first Starlink satellites were launched into low-earth orbit in the first half of 2019. First, these devices fall to an altitude of 440 kilometers, and then turn on their engines and rise to 550 kilometers. Since at that time they strongly reflected sunlight, it was possible to notice them in the sky even with the naked eye. The string of satellites was clearly visible over the Netherlands, and amateur astronomer Marco Langbroek was even able to capture the phenomenon on video.

Starlink satellites may interfere with the detection of dangerous asteroids like 450-meter Apophis

As you can see, SpaceX is trying to somehowsolve the problem of. But there are other companies in the world that want to launch their own satellite Internet. OneWeb has been implementing a similar idea for a long time, and recently it became known that Amazon wants to join this race. The Chinese company GW plans to launch as many as 13,000 satellites into orbit of our planet, and it is not yet clear whether they will be equipped with protective satellites or not. Astronomer Jonathan McDowell mentioned above is also concerned that some companies like OneWeb want to send their satellites into higher orbit. This means that they can interfere with the work of even space satellites. But this is fraught not only with the fact that scientists will have difficulty studying space. They also need to monitor the movement of asteroids, one of which may well fly towards our planet in the future. If you do not notice them in time and do not take action, a disaster can happen.

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And this is not a joke, because potentially dangerousfor our planet, asteroids do exist. One of them is Apophis, which recently changed its trajectory and will approach the Earth on April 13, 2029. According to the calculations of scientists, it will fly at a distance of 29,470 kilometers from the surface of our planet. The next approach of the asteroid is expected in 2036 and it is not yet clear to scientists how dangerous this event will be. You can read more about why a space object suddenly turned from its original path in this material.