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The launch of 60 Starlink satellites by Elon Musk SpaceX has caught the attention of people around the world. Satellites are part of a fleet designed to provide fast Internet access worldwide.
Are we going to lose the night sky in favor of city lights and satellites?
Jeff Sullivan, BY-NC-ND CC
Starlink's ambitious mission
Starlink is an ambitious plan to use satellites in low Earth orbit (about 500 km up) to provide global Internet services.
This approach is different from the one previously used for most communication satellites, in which larger individual satellites were placed in high geosynchronous orbits – which remain in a seemingly fixed position above the equator (about 36 000 km).
Communications with satellites in geosynchronous orbits often require satellite dishes visible on the sides of residential buildings. Communications with satellites in low Earth orbit, much closer, will not require such large equipment.
But capturing low-Earth-orbiting satellites around the world is that they can only watch in a small way, so to get global coverage, you need multiple satellites.
The Iridium satellite network used this approach in the 1990s, using dozens of satellites to provide global voice and data services.
Starlink is much more ambitious, with 1,600 satellites in the first phase and 12,000 satellites in the mid-2020s. By comparison, about 18,000 objects in Earth orbit are tracked, including about 2,000 satellites in operation.
Lights in the sky
It is not uncommon to see satellites traveling in the twilight sky. Indeed, it is very exciting to see the International Space Station pbad overhead and know that people live aboard this distant light. But Starlink, it's something else.
The first 60 satellites, launched by SpaceX last week, have been seen traveling in procession in the night sky. Some people knew what they saw, but the silent procession of light also generated reports of UFOs. If you are lucky, you may see them crossing your sky tonight.
If the entire constellation of satellites is launched, hundreds of Starlink satellites will be above the horizon at any time. If they are visible to the naked eye, as suggested by the initial reports, they could outnumber the brightest natural stars visible to the naked eye.
Astronomers fears Musk's tweets:
Satellites are very clearly visible at night, especially before dawn and after sunset, as they are high enough to be illuminated by the sun. The artificial lighting of the Space Station does not affect its visibility.
In areas near the poles, including Canada and northern Europe, satellites in low Earth orbit can be illuminated all night during the summer months.
Hundreds of satellites visible to the naked eye would be a disaster. They would ruin our vision of the night sky completely. They would also contaminate astronomical images, leaving long streaks through unblemished images.
Based in Chile, the $ 644-million Synoptic Survey Large Telescope is an 8-meter-wide telescope equipped with a 3200-megapixel camera. It is designed to quickly examine the sky during the 2020s.
With the complete constellation of Starlink satellites, many images taken with this telescope will contain a Starlink satellite. Longer exposures may contain dozens of satellite trails.
Dark sky or darkened hopes?
Is there a reason to be optimistic? Yes and no.
Musk has produced some amazing technological achievements, such as the SpaceX Falcon and Tesla, but he has also disappointed some projects, such as the Hyperloop tunnel transport plan.
While Starlink certainly exploded on Twitterfor the moment at least, Musk has 11,940 satellites out of 12,000.
In addition, the early reports may have overestimated the luminosity of the Starlink satellites, as the multiple closely clustered satellites were mistaken for a satellite.
Some reports indicate that binoculars are needed to view different satellites, but point out that Starlink satellites flare, becoming momentarily brighter than any natural star.
If the individual satellites are generally too weak to be seen with the naked eye, it would at least preserve the natural wonder of the sky. But professional astronomers like myself may have to prepare for unstable skies. I can not say that I look forward to it.
Michael J. I. Brown, Associate Professor of Astronomy, Monash University
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