It’s not too late to save the night sky, but governments must take its protection seriously – .

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It’s not too late to save the night sky, but governments must take its protection seriously – .


Megaconstellations threaten to affect the quality of stargazing. Credit: Shutterstock

In early 2021, just after the Perseverance Rover landed on Mars, an alleged image of the Martian night sky went viral. In this image, above the smooth metal of a Martian rover, the clearly defined Milky Way cuts from horizon to horizon, crossing a sky filled with so many stars that there is no darkness.

Millions of people were delighted to see the unblemished night sky of another planet, without city light pollution, without blinking planes, and without significant satellite presence.

The photo is not real; rather, it is a clever juxtaposition of NASA images and long exposure astrophotography. So why did it go viral?

The threatened night sky

Urban light pollution has dramatically changed our relationship with the night sky: 80% of North Americans cannot see the Milky Way from where they live today. Electricity is so cheap and plentiful that we use it to light up the skies for no other reason than laziness and poor planning.

The lack of darkness that many people now feel due to urban light pollution has been linked to many physical and mental health issues, both in humans and in wildlife.

But today we are faced with a new source of light pollution: the systems of tens of thousands of communication satellites. The construction of these so-called mega-stellations is already changing the night sky.

Indeed, observations of professional astronomers have shown that many of the current satellites in the Starlink mega-constellation are visible to the naked eye when illuminated by the sun.







The Losing the Sky event hosted by the University of Edinburgh brought together astronomers, industry representatives and space law experts to discuss the future of the night sky.

Megaconstellations have the potential to significantly benefit society by increasing the connectivity of isolated communities, a significant challenge in many parts of Canada. At the same time, the negative effects of mega-constellations need to be understood by policymakers and properly regulated.

While city dwellers may not notice this change, many people around the world will, especially those from cultures closely related to stargazing and traditional knowledge of the sky.

Canada has an obligation to consult with First Nations so that each can make an independent decision before authorizing the development of a resource to which Indigenous Canadians have traditionally had access for cultural practices.

The damage done to science

Astronomical organizations around the world are concerned about the damage to science that will be caused by mega-stellations and other forms of light and radio pollution, and have responded with efforts such as the “Dark and Quiet Skies Report” and the “SATCON1 Report”.

Astronomers will need more time at the telescope to achieve the same taxpayer-funded science goals, and will have to spend time and money studying the brightness of these satellites and developing new software for mitigation efforts. .

Radio astronomers expect to lose even more radio spectrum due to mega-constellation communication noise, requiring additional investment in research and development.

At the request of the Canadian Astronomical Society, we have produced a report containing a list of recommendations on what Canada can do to address the many negative impacts of mega-constellations nationally and internationally.

The number of satellites illuminated by the sun and above the horizon at different latitudes on Earth at different times of the night during the June solstice. Yellow is the highest density: more than 3,000 sunlit satellites at this time. Credit: Samantha Lawler / Aaron Boley

A sky full of satellites

We ran a simulation with 65,000 satellites in their proposed orbits (this includes Starlink, OneWeb, Kuiper and StarNet / GW). We have found that there will be over 1,500 sunlit satellites at any time all night, every night in the summer from Canada. Not all of them will be visible, as their brightness depends on the shape, reflective properties and orbit of each satellite. But there are currently no regulations that limit their brightness.

There are currently around 20,000 tracked objects in orbit, including active satellites, dead satellites, rocket bodies and space debris. There is 10 to 100 times more untracked space debris that is small but still dangerous: tiny debris from rocket launches, satellite deployments, fragmentations (explosions) and even tools dropped by astronauts.

These small objects seem harmless, but in low earth orbit (LEO) they travel at speeds of over seven kilometers per second, several times faster than a bullet, in randomly crossing orbits.

Companies are making substantial progress to place at least 65,000 satellites in LEO. The current leader SpaceX already has more than 1,600 Starlink satellites in orbit, in a region inhabited by a worrying density of untracked debris.

When two satellites collide (as first happened in 2009), they produce a rapidly moving shower of debris. A destroyed satellite produces hundreds or even thousands of traceable space debris, each of which can destroy other satellites, producing even more space debris. Any major fragmentation event will impose limitations on the use of space, endanger the crewed LEO space accommodation, and could cause widespread disruption to the services we rely on every day.

Reentry of space debris

As highlighted by the recent uncontrolled re-entries of the Long March 5B rocket thruster over the Indian Ocean in May 2021 and the SpaceX Falcon 9 rocket stage over the Pacific Northwest in March 2021, the re-entries are not without risks. Part of the Falcon 9 rocket from March 2021 even survived an impact with the ground in a farmer’s field in Washington state.

Collisions between satellites create space debris, which can cause damage when it falls to Earth. Credit: Shutterstock

The current rules date back to the era of the space race. There is an accountability framework, but the only time it has been tested is when a USSR satellite dumped nuclear waste into the Northwest Territories in 1978.

There are also environmental impacts, both from rocket launching and the elimination of satellites. SpaceX plans 42,000 Starlink satellites to be replaced every five years. This means that on average six tonnes of satellites will be destroyed. everyday. This material will be deposited in the upper atmosphere during the re-entry. Although this is less than the 54 tonnes of meteorites that hit Earth’s atmosphere each day, the makeup is very different: Starlink satellites are mostly aluminum by weight; meteoroids make up one percent.

We don’t know what could happen when several tons of aluminum are deposited in the upper atmosphere every day. SpaceX will conduct this experiment without any environmental oversight.

Due to the orientation of the orbits of the proposed satellites, a large portion of the Canadian population will be in some of the highest satellite densities, so we can expect to see a disproportionate share of deorbiting space debris.

Satellite regulation is the key

We must recognize that LEO is inextricably linked to our atmosphere, our oceans and our lands. We need satellite regulation now, before there is irreparable damage to our skies. We hope that the Government of Canada will act on these recommendations with an urgency that matches the breakneck speed of space development.

While several mega-constellation companies are already in dialogue with astronomers, the improvements they make to their satellites for the benefit of astronomy are entirely voluntary. We shouldn’t have to choose between the night sky and the global internet. With good regulation of satellites in LEO, we can have both.


Starlink and OneWeb Have Their First Avoidance Maneuver With Each Other’s Constellations


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Citation: It’s not too late to save the night sky, but governments must take its protection seriously (2021, June 25) retrieved June 25, 2021 from https://phys.org/news/2021-06-late -night-sky .html

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