Brilliant New Constellation or Light Pollution?

D​are to Know readers will be aware of the term “light pollution”. It’s the bane of astronomers and star gazers everywhere. The more that we humans have developed the world around us, the more lights we have put up. If you live in an urban area, or even a small town, lighting is everywhere you look. We’re told that all this lighting makes us safer. Sometimes, I think it’s a false sense of security.

Anyway, light pollution is a problem for those of us who like to look up at the night sky with reverence. It blocks out the faint objects we love to look at. This is also true for professional astronomers. Observatories have to be located in more and more remote areas to be useful. City lights make existing locations obsolete.

For example, the Stewart Observatory at my alma mater, the University of Toronto is now defunct. Located in the downtown core, light pollution forced the university to build the David Dunlop Observatory on the outskirts of the city in the 1930s. The dome of the Stewart Observatory is nothing more than an architectural novelty today. The occasional target of merry pranksters who have a tradition of painting it unusual colours from time to time, it serves no real purpose anymore. You can’t see the night sky from the downtown campus in our modern age.

We are now facing a threat from a new kind of light pollution. It’s a controversial topic for the people who read our Cosmology category. Most of our readers are star gazers, staunch supporters of the space program and also believe in broadband for all. As a society, we are discovering that these three activities may not be compatible.

The new kind of light pollution we are discussing comes from satellites. The debate was sparked by a project being launched by Elon Musk’s company SpaceX. It’s called Starlink, and its goal is to launch 12,000 new satellites into low earth orbit. As I write this, the first 60 took off a couple of weeks ago. Musk told the press that the satellites would be “barely noticeable” to star gazers but that doesn’t seem to be the case. Observers have been able to spot, photograph and track them effortlessly. They have turned out to be more than noticeable.

Astronomers are concerned about two issues. First, 5,000 satellites are now in low earth orbit. Starlink will more than triple that total number. Will this cause an orbital traffic jam? Space-X says that the autonomous Starlink satellites are programmed to avoid collisions with other objects. They also say that the satellites will burn up on re-entry at the end of their useful life. They say that this will leave no space junk behind. Experts are skeptical.

The second concern is their brightness. At first, reports went around that the satellites would have a brightness of about magnitude 2. This would make them as bright as the North Star, Polaris. This seems to be an exaggeration. Experts now say that they reflect sunlight at about magnitude 6. This won’t be an issue for casual stargazers. More serious astronomers will find this annoying. Observatories will probably have satellites photo bombing their images with bright streaks on most frames. This will be no more than a nuisance most of the time. Yet, we have an ethical dilemma here. Who decides whether to change the appearance of everyone’s night skies?

What’s worse, these satellites will send signals at or near frequencies used by radio telescopes. This may interfere with their observations of distant celestial objects. We have no practical way to shield radio telescopes from these signals while still allowing them to receive the emissions they are receiving from space.

Space-X is working to reassure the public. Musk has told us that he has asked his team to find ways to reduce the satellites’ brightness. To be fair, companies other than Space-X have similar plans. One-Web is another organization that wants to launch a network of satellites into low earth orbit. Space-X has taken all the required steps to follow current regulations. Starlink was approved by the International Telecommunications Union (ITU) and the Federal Communications Commission (FCC). This is not Elon Musk doing a vanity project or doing an end run as some have alleged.

Those of us who love science have a dilemma. We want to see broadband for everyone on earth so that they can access the knowledge they desperately need. That’s what Starlink is about. We also enjoy seeing the private sector excel in space exploration. Yet, we’re learning that this progress may have a tragic cost.

As a society, we need to find out what the impact of all these satellites will be on our night sky. Nobody seems to know this yet. Estimates appear inaccurate. If we wait until they have all been launched, it will be too late to do anything about it. We need answers now so that we can balance our priorities between clear skies, broadband access and space exploration.

At this point, I’m seeing more heat than light being generated around this topic on all sides.

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