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This is how Elon Musk can fix the damage his Starlink satellites are doing to astronomy.




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In any field of business or industry, the prevailing rule has always been that if there is no law against it, you are free to do so. If there are no rules to protect a resource, you are free to use it or use it as much as you like to promote your own purposes. & Nbsp; Until regulatory measures are implemented, disruptors and innovators can be regulated, often to the extraordinary detriment of those who depended on these now scarce resources.

In astronomy, the greatest resource of all is a dark and clear night sky: humanity's window to the universe. Traditionally, its enemies are turbulent air, clouds and artificial light pollution. But very recently, a new type of pollutant has begun to pose an existential threat to astronomy itself: mega-constellations of satellites. If Elon Musk's Starlink project continues as it began, it will probably end terrestrial astronomy as we know it.

Launching satellites to serve those living on the ground is an essential part of modern life. GPS and telecommunications satellites enable our cellular signals and support our mobile Internet today. With the next update for 5G services, a new set of infrastructure will be required, and this necessarily means an updated set of satellites equipped to provide this service.

One of the first companies to attempt to serve this market is SpaceX, under the guidance of Elon Musk, who initially plans to deploy 12,000 satellites in a mega constellation known as Starlink. Finally, the constellation expects to extend to a total of 42,000 satellites. As of November 20, 2019, only 122 of these satellites have been deployed and have had a negative impact on astronomy on a global scale.

If we hope to mitigate this, SpaceX's regulators or executives themselves will need to demand a change.

Of the darkest skies you can find on Earth, approximately 9,000 stars are visible to human eyes: up to a visual magnitude of +6.5, the limit of human vision. & Nbsp; However, the first 122 satellites launched by Starlink are not only brighter than the others. In most of these stars, they move rapidly across the sky, leaving trails that pollute astronomers' data.

If these satellites were weak, few in number, or moving slowly, that would be only a minor problem. If you were just looking at a narrow region of the sky, you would simply reject all exposure frames (or even just their pixels) where offensive objects spread across the sky. But with a large number of bright, fast-moving satellites, especially if you're looking for frame-by-frame changes (as many current and future observatories are designed to do), you need to discard any exposure frames with these artifacts on them .

On November 18, 2019, a series of 19 of these Starlink satellites went through the website of the Cerro Tololo Inter-American Observatory in Chile., lasting more than 5 minutes and strongly affecting the wide field DECam instrument, which creates images in a field that contains 3 square degrees with an excellent resolution of 0.263 arc seconds per pixel.

While this represents only 0.3% of the total number of proposed Starlink satellites that SpaceX wants to launch, the consequences are clear: wide-field astronomy designed to look for weak objects – main objectives of observatories such as Pan-STARRS, LSST and any satellite program. observation aimed at finding objects potentially hazardous to Earth will be significantly impaired. Frame averaging is not a desired option because it erases the ability of astronomers to study the object's natural variability, another important goal of science. Because Starlink satellites autonomously alter their orbits and are extremely noisy, terrestrial observations cannot be scheduled to avoid them.

In addition, these satellites are not in traditional low Earth orbits, which will decay and return to Earth over time scales of months, years or (at most) decades, these satellites are at altitudes greater than 1,000 km, where orbital decay will occur. take millennia. As early as September, ESA's Aeolus satellite (used for Earth observation) had to make an emergency maneuver to avoid colliding with a SpaceX Starlink satellite, although it is SpaceX's responsibility to change.

Although SpaceX and Musk have issued statements claiming that:

All of these statements are not yet true as of November 20, 2019.

Previous satellite constellations, such as the extremely successful Iridium constellation, proceeded in clearly defined and predictable orbits, were few in number (66 in total) and only shone brightly when their orientation reflected sunlight in a particular way. Starlink satellites, along with similar planned constellations such as Kuiper Systems and OneWeb, represent a unique new obstacle to terrestrial astronomy.

According to Cees Bassa of the Dutch Institute of Radioastronomy, up to 140 of these satellites will be visible at any time in all observatories on Earth. However, if the companies behind these new constellations are willing to take just a few simple steps, all of these obstacles can be overcome. Here's what a responsible night sky manager should do, and how SpaceX can undo the damage it is inflicting on astronomy.

1.) Debit the current batch of Starlink satellites and place a moratorium on the launch of new satellites until the appropriate modifications are made.. Unlike most GPS and communication satellites we have today, today's Starlink satellites are large, reflective and are already causing some astronomers to throw significant portions of their data. Today, at an altitude of 280 km where they are visible to the naked eye, they can now be easily and safely cleared.

But when they are raised to 550 km of operating altitude, they become a much more permanent problem. In addition, public awareness will fall, but they will remain visible to all binoculars and telescopes: the astronomer's most essential tools. Every time these satellites are up there, there's the astronomical equivalent of callously rolling coal in front of every scientist, researcher, and especially undergraduate and graduate students who depend on a difficult time getting on the telescope to start their careers.

2.) Redesign or coat the satellites to significantly reduce their reflectivity.. Part of the problem with these new satellites is that they are large and highly reflective. But these problems are unnecessary: ​​they are choices. Choosing a different design where satellites can be oriented to minimize impact on astronomy would improve the problem. Even more economically, simply covering satellites with a very dark outer layer and a low albedo index would greatly help to reduce the astronomically polluting effects of this constellation.

Albedo's reduction, as is clear from today's Starlink satellites, was not even considered as part of the design. By incorporating some common sense steps to reduce it – and I know many astronomers willing to help with recommendations – the apparent brightness of these satellites can be reduced by a factor of approximately ~ 100.

3.) Provide real-time trajectory plans, forecasts and adjustment information for each satellite to observatories around the world.. One of the worst things about these satellites is that they come without predictable trajectories. If their paths were known, astronomers could schedule observations that absolutely minimized their impact on science by making good use of all the good times.

It should not only be easy, but mandatory, to set up a global network that tracks the predicted paths of each satellite in real time, continuously updated to account for any maneuvers or course corrections that have been made. By providing this information to astronomers, polluted areas can be avoided at any time while still providing quality observations of as much sky as possible.

4.) Provide funding to help astronomers develop hardware and software-driven solutions to subtract satellite pollution as much as possible.. Even if all these steps are taken, it will still be an arduous and expensive task for astronomers to explain the contamination that remains in their data. It is not reasonable to expect Starlink or any satellite-based company to have any impact on astronomy, but it is extremely reasonable to require them to fund the mitigation efforts that astronomers will need to undertake.

This is how literally every other industry in the world works: if you plunder any aspect of the natural environment, you must restore the damage you have caused. Astronomers I know don't care that you have satellites up there; they worry that they can still do their work despite them. It really is not too much to ask.

At the moment, the Outer Space Treaty only prohibits the militarized use of space; all peaceful purposes are permitted. There are no consequences for damage to the night sky and there are no regulations on pollution or contamination. As long as you register your satellite (s) and do not cause a collision in orbit or on Earth, there is no legal responsibility for what you do.

The astronomical community's only options are to try to pass laws that protect the night sky or wait for the industry to self-regulate. If companies like SpaceX, Kuiper Systems, and OneWeb follow the selfless path of addressing these issues in Before Causing Widespread Problems, they will truly be worthy captains of this thriving industry. But it is very frightening to be entering an era when the future of one of the oldest sciences of humanity depends on the ethical bar of some for-profit companies. Our understanding of the universe, from nearby dangerous objects to the distant corners of space, is no longer in the hands of astronomers.

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In any field of business or industry, the prevailing rule has always been that if there is no law against it, you are free to do so. If there are no rules to protect a resource, you can use it or use it as much as you like to promote your own purposes. Until regulatory measures are implemented, disruptors and innovators are free to regulate themselves, often to the extraordinary detriment of those who depended on these now scarce resources.

In astronomy, the greatest resource of all is a dark and clear night sky: humanity's window to the universe. Traditionally, its enemies are turbulent air, clouds and artificial light pollution. But very recently, a new type of pollutant has begun to pose an existential threat to astronomy itself: mega-constellations of satellites. If Elon Musk's Starlink project continues as it began, it will probably end terrestrial astronomy as we know it.

Launching satellites to serve those living on the ground is an essential part of modern life. GPS and telecommunications satellites enable our cellular signals and support our mobile Internet today. With the next update for 5G services, a new set of infrastructure will be required, and this necessarily means an updated set of satellites equipped to provide this service.

One of the first companies to attempt to serve this market is SpaceX, under the guidance of Elon Musk, who initially plans to deploy 12,000 satellites in a mega constellation known as Starlink. Finally, the constellation expects to extend to a total of 42,000 satellites. As of November 20, 2019, only 122 of these satellites have been deployed and have had a negative impact on astronomy on a global scale.

If we hope to mitigate this, SpaceX's regulators or executives themselves will need to demand a change.

Of the darkest skies you can find on Earth, approximately 9,000 stars are visible to human eyes: up to a visual magnitude of +6.5, the limit of human vision. However, the first 122 satellites launched by Starlink are not only brighter than most of these stars, they move rapidly across the sky, leaving traces that pollute astronomers' data.

If these satellites were weak, few in number, or moving slowly, that would be only a minor problem. If you were just looking at a narrow region of the sky, you would simply reject all exposure frames (or even just their pixels) where offensive objects spread across the sky. But with a large number of bright, fast-moving satellites, especially if you're looking for frame-by-frame changes (as many current and future observatories are designed to do), you need to discard any exposure frames with these artifacts on them .

On November 18, 2019, a series of 19 of these Starlink satellites passed the Cerro Tololo Inter-American Observatory website in Chile, lasting more than 5 minutes and strongly affecting the wide field DECam instrument, which creates images in a field that contains 3 square degrees with an excellent resolution of 0.263 arc seconds per pixel.

While this represents only 0.3% of the total number of proposed Starlink satellites SpaceX wants to launch, the consequences are clear: wide-field astronomy designed to look for weak objects – main objectives of observatories like Pan-STARRS, LSST and any other program. observing the discovery of potentially dangerous objects to Earth – will be significantly impaired. Frame averaging is not a desired option because it erases the ability of astronomers to study the object's natural variability, another important goal of science. Because Starlink satellites autonomously alter their orbits and are extremely noisy, terrestrial observations cannot be scheduled to avoid them.

In addition, these satellites are not in traditional low Earth orbits, which will decay and return to Earth over time scales of months, years or (at most) decades, these satellites are at altitudes greater than 1,000 km, where orbital decay will occur. take millennia. By September, ESA's Aeolus satellite (used for Earth observation) had to make an emergency maneuver to avoid colliding with a SpaceX Starlink satellite, despite the fact that it was SpaceX's responsibility to move.

Although SpaceX and Musk have issued statements claiming that:

All of these statements are not yet true as of November 20, 2019.

Previous satellite constellations, such as the extremely successful Iridium constellation, proceeded in clearly defined and predictable orbits, were few in number (66 in total) and only shone brightly when their orientation reflected sunlight in a particular way. Starlink satellites, along with similar planned constellations such as Kuiper Systems and OneWeb, represent a unique new obstacle to terrestrial astronomy.

According to Cees Bassa of the Dutch Institute of Radioastronomy, up to 140 of these satellites will be visible at any time in all observatories on Earth. However, if the companies behind these new constellations are willing to take just a few simple steps, all of these obstacles can be overcome. Here's what a responsible night sky manager should do, and how SpaceX can undo the damage it is inflicting on astronomy.

1.) Debit the current batch of Starlink satellites and place a moratorium on the launch of new satellites until the appropriate modifications are made.. Unlike most GPS and communication satellites we have today, today's Starlink satellites are large, reflective and are already causing some astronomers to throw significant portions of their data. Today, at an altitude of 280 km where they are visible to the naked eye, they can now be easily and safely cleared.

But when they are raised to 550 km of operating altitude, they become a much more permanent problem. In addition, public awareness will fall, but they will remain visible to all binoculars and telescopes: the astronomer's most essential tools. Every time these satellites are in operation, there is the astronomical equivalent of coal rolling callously in the face of every scientist, researcher, and especially undergraduate and graduate students who depend on a hard time getting in the telescope to get started. their careers.

2.) Redesign or coat the satellites to significantly reduce their reflectivity.. Part of the problem with these new satellites is that they are large and highly reflective. But these problems are unnecessary: ​​they are choices. Choosing a different design where satellites can be oriented to minimize impact on astronomy would improve the problem. Even more economically, simply covering satellites with a very dark outer layer and a low albedo index would greatly help to reduce the astronomically polluting effects of this constellation.

Albedo's shrinkage, as is clear from today's Starlink satellites, has not even been considered as part of the design. By incorporating some common sense steps to reduce it – and I know many astronomers willing to help with recommendations – the apparent brightness of these satellites can be reduced by a factor of approximately ~ 100.

3.) Provide real-time trajectory plans, forecasts and adjustment information for each satellite to observatories around the world.. One of the worst things about these satellites is that they come without predictable trajectories. If their paths were known, astronomers could schedule observations that absolutely minimized their impact on science by making good use of all the good times.

It should not only be easy, but mandatory, to set up a global network that tracks the predicted paths of each satellite in real time, continuously updated to account for any maneuvers or course corrections that have been made. By providing this information to astronomers, polluted areas can be avoided at any time while still providing quality observations of as much sky as possible.

4.) Provide funding to help astronomers develop hardware and software-driven solutions to subtract satellite pollution as much as possible.. Even if all these steps are taken, it will still be an arduous and expensive task for astronomers to explain the contamination that remains in their data. It is not reasonable to expect Starlink or any satellite-based company to have any impact on astronomy, but it is extremely reasonable to require them to fund the mitigation efforts that astronomers will need to undertake.

This is how literally every other industry in the world works: if you plunder any aspect of the natural environment, you must restore the damage you have caused. Astronomers I know don't care that you have satellites up there; they worry that they can still do their work despite them. It really is not too much to ask.

At the moment, the Outer Space Treaty only prohibits the militarized use of space; all peaceful purposes are permitted. There are no consequences for damage to the night sky and no regulations on pollution or contamination. As long as you register your satellite (s) and do not collide in orbit or on Earth, there is no legal responsibility for what you do.

The astronomical community's only options are: trying to pass laws protecting the night sky or waiting for the industry to self-regulate. If companies like SpaceX, Kuiper Systems, and OneWeb follow the selfless way of addressing these issues before causing widespread problems, they really will be worthy captains of this thriving industry. Mas é muito assustador estar entrando em uma era em que o futuro de uma das ciências mais antigas da humanidade depende dos compassos éticos de algumas empresas com fins lucrativos. Nossa compreensão do Universo, desde objetos perigosos próximos até os recantos distantes do espaço, não está mais nas mãos dos astrônomos.


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