Is the night sky part of our natural environment? Some astronomers say yes, and try to preserve it


Astronomer Samantha Lawler emerged from her farm in Edenwold, about 30 kilometers northeast of Regina, her feet crunching on the snow below, the cacophony of ducks and chickens emanating from her barn.

It was early morning, before sunrise, and the stars were still draped in the sky.

She looked up on her short walk and noticed the slow movement of light among the stars. Then another. And another. Eventually she stopped counting.

Lawler knew only too well what these false stars were: satellites.

“I wasn’t even looking at the sky. I was looking and walking between buildings and I saw a dozen in the space of a minute looking up,” she said. “I mean, it’s really bad. It’s pretty noticeable.”

And it’s about to get worse.

Astronomers around the world are concerned that a handful of commercial companies – primarily SpaceX – are proposing to flood low Earth orbit with tens of thousands of these satellites, with the potential to far exceed that. There is also the risk of satellites crashing into each other and adding to the thousands of space debris already in orbit.

All of this, astronomers say, is a threat to the preservation of our night sky.

This image of the Pleiades star cluster shows the trajectories of Starlink satellites. The reflective surfaces of the satellites, coupled with the fact that they orbit the Earth, mean that astronomical observations that require very long exposures capture “traces” of the satellites in their images. (T. Hansen/IAU OAE/Creative Commons)

Consequently, on February 3, the The International Astronomical Union (IAU) has announced the creation of the Center for the Protection of Dark and Calm Skies from Satellite Constellation Interference. Their goal is clear: to work with industry leaders, amateur astronomers, Indigenous groups and scientists around the world to protect the sanctity of the night sky.

So far, there has been little to no disagreement between astronomers and industry leaders.

“The experience we’ve had interacting with industry is that they’ve been extremely cooperative in trying to manage their individual objects and the amount of light they scatter,” said Richard L. Green, astronomer at the ‘University of Arizona. who is part of the executive committee working group on sky protection.

But that could change.

“There is always a caveat, because [industry] can’t do much,” said Connie Walker, co-director of the new center and an astronomer at the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab).

“They’re there to make a profit. But I think we’ve got their ear, especially right now. And I think there’s genuine good will, trying to do everything they can. But it has limits .”

This is why some astronomers suggest that society as a whole must act preemptively and consider our skies and low Earth orbit as part of our natural environment and worth preserving.

Deeper concerns about the environment

The night sky has been a driving force in human history. We used the stars to navigate, to help us decide when to plant, and to record the weather. We tracked the planets and noted when a new “star” (a supernova explosion) appeared in the heavens.

But these days, the Milky Way is something most people have only seen in photos or on TV. A A 2018 study found that the Milky Way is hidden from around a third of humanity, including 80% of North Americans.

This map shows the artificial brightness of the North American sky, in two increasing steps, as a ratio to the natural sky brightness. Black represents little or no light pollution, while yellow, red, and white represent the most light pollution where few stars are visible in the night sky. (Fabio Falchi, Christopher Kyba, and others)

But there’s another issue that concerns Lawler, one that doesn’t involve the night sky.

Starlink satellites, which provide high-speed Internet access to rural areas, have a life expectancy of about five yearsafter which they will be desorbed and burned up in the earth’s atmosphere.

“If you do the math, they want to replace 42,000 satellites every five years,” said Lawler, who wrote an assessment on constellations for the federal government. “That means they’ll deorbit 23 a day. When you look at their mass, they’re the size of a car, right? So that’s six tonnes, mostly aluminum, that will be added in the upper atmosphere every day.”

Why is this important?

In the fight against climate change, the injection of alumina particles in the upper atmosphere have been proposed to help cool the planetbut the wider implications are not yet fully understood.

“Low Earth orbit is not legally considered an environment,” Lawler said. “So no one is watching this.”

There’s also another way to look at it: how these satellites impact cultures that have relied on the stars throughout history.

“You could go so far as to say, well, you know, the Truth and Reconciliation Commission’s Calls to Action say that if a private company is going to take resources away from Indigenous peoples, they need to be consulted, given their permission and be compensated,” Lawler said. “Does that count? Getting a private company to make a profit by destroying a resource it has had access to for thousands of years? »

Some ongoing efforts

Satellites are responsible for so many things in our daily lives, from global positioning systems that help us get around, from weather satellites to Earth monitoring satellites.

According to the Space Debris Office of the European Space Agency, as of January 5, there were around 7,840 satellites in orbit, of which around 5,100 are still operational.

However, in the 65 years since the Soviet Union launched Sputnik – the first artificial satellite – many satellites are now in the hands of commercial industry, with little regulation.

And SpaceX is leading the charge. To date, the company has launched approximately 2,000 Starlink satellites aimed at bringing internet access to even the most remote areas of the globe, with plans to launch more than 42,000.

But there are also other players, including that of Jeff Bezos Amazon/Project KuiperEurope OneWeb and that of Canada Telesat.

WATCH | Future Canada/Europe satellite simulations at the summer solstice. The yellow dots are the brightest satellites, the blue ones are the faintest:

There are even websites, such as SatelliteMap.Spacewhere you can track SpaceX and OneWeb satellites in real time and determine when they will pass overhead. ESRI has developed a beta website which allows viewers to see the amount of space junk and orbiting satellites.

There are also dedicated applications, such as Mega Constellations, developed by Canadian astronomer Hanno Rein. (ESA has calculated that there are currently more than a million pieces of debris measuring 1-10cm that can pose a hazard to satellites and astronauts.)

When the first batch of Starlinks launched in 2019, astronomers and industry leaders were surprised at how bright the satellite train was. (SpaceX initially launches them at around 200 km altitude, before deploying them at around 500 km.)

The company was quick to respond to astronomers’ complaints and sought to reduce their reflectivity – first with paint, then with some type of shield. Although this helped, it did not eliminate the problem.

WATCH | Amateur astronomer Alan Dyer captures Starlink satellites from southern Alberta in 2019:

OneWeb, which initially aimed to launch nearly 48,000, narrowed down its proposal to around 6,400 satellites.

It’s a step in the right direction, say astronomers.

“I think we bought time because Starlink accepted a higher price [orbit] and OneWeb has dramatically reduced their total number of satellites,” said Jonathan McDowell, an astronomer at Harvard University’s Center for Astrophysics who has also been involved in IAU working groups.

“So I think that’s going to keep the impact of astronomy in the next few years at a super annoying level, rather than fatal.”

Lawler does not necessarily share this optimism.

“There are a lot of engineering issues that I think [industry] could rise to the challenge [of], but they just don’t see them, they only see the bare minimum to make the most money,” she said. “And that’s all they focus on. The consequences of this are that we could lose the ability to use orbit safely, in addition to destroying the sky and the atmosphere.”

SpaceX did not respond to an interview request. Telesat was unavailable to speak with CBC News at the time of publication.

pressure on science

When it comes to astronomy – most of which is publicly funded – reducing brightness or altitude isn’t quite enough.

When astronomers collect data, they often take long-exposure photographs, sometimes of the entire sky. Although satellites at higher altitudes may be invisible to the naked eye, they are picked up by large telescopes and appear as long streaks in these images.

McDowell, who is currently working on algorithms to help astronomers process these satellites in images, said it’s not as simple as using software to remove contrails.

WATCH | Starlinks will cross the Cerro Tololo Inter-American Observatory in 2020:

“People will be like, ‘Oh, that’s okay. You just Photoshop and erase the footage, right?'” McDowell said. “Well, no, because we’re trying to measure the brightness of stars at, like, one percent. So it doesn’t work.”

Then there is the potential impact on radio astronomy.

Canada has invested $290 million in the Square Kilometer Array Observatory (SKAO) in South Africa, where 197 radio astronomy dishes will together become the largest radio astronomy dish in the world. It is a radio silence zone where even cell phones are not allowed.

However, constellations of satellites threaten the observatory, which will open at the end of the decade. A recent SKAO analysis suggests that they could lose a significant amount of sensitivity to certain molecules, impacting their research.

The new IAU center is still in its infancy, but it has big goals. He held several working groups on the issuedevelops industry standards and works with the United Nations Committee on the Peaceful Uses of Outer Space.

McDowell said it was a matter of solving the problem now, before it was too late.

“As is always the case with environmental issues, it’s nothing happens until it’s really bad,” he said. “And then people say, ‘Oh, I guess we should do something. “”


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