At dawn on November 18, 2019, Cliff Johnson, an astronomer at Northwestern University in the United States, spotted a large group of unidentified objects passing through the sky. That night, Johnson was observing the Magellan Nebula through a webcam. These unidentified objects do not come from the outside world, but from the earth. Within five minutes, 19 satellites were in sight of the telescope, leaving behind several rows of bright tails.
Soon, Johnson and his colleagues found out where the satellites came from — a week after Elon Musk’s SpaceX launched 60 small satellites into low-Earth orbit.
Astronomers can occasionally see satellites when they observe — something they’re used to. However, they have only seen one at a time in the past, which does not affect the observations, although it will take some effort to finally remove the satellite from the observational images.
But what if it’s 19? This is unprecedented, resulting in 15 to 20 per cent of images being “completely lost”.
Even more worrying for Johnson is that this could become the norm – all astronomical observations made at dawn will be disrupted by the satellite’s tail.
The Earth will soon be covered by thousands of satellites, and they will be far more than 9,000 — the number of stars visible to the naked eye.
This is not a worry. Add in the 60 launched last Monday, and SpaceX has launched 180 small satellites, which may be launched every two weeks thereafter – this is Musk’s satellite Internet program, Starlink.
The Federal Communications Commission (FCC) has approved SpaceX’s launch of 12,000 satellites. For now, Musk is trying to get another 30,000 satellites approved.
SpaceX’s goal is to build a satellite base in space through the Starlink project, which will provide a fee-paying Internet service in remote areas.
SpaceX is not alone in this regard. Britain-based OneWeb also wants to break into the “space internet” market and plans to start launching 650 satellites in January; Amazon’s Kuiper Global Satellite Broadband project plans to launch 3,200 satellites. In the near future, 50,000 or more small satellites will appear around the Earth, perhaps for far more than the “Internet” – perhaps some companies want to spell out the name of a famous soda in space? After all, space advertising has not been banned.
These mass-launched satellites are small, many, and close to Earth to ensure the speed of future Internet connection services. But “getting closer” doesn’t mean “seeing clearly” or “brighter” in the night sky. “But SpaceX’s satellites are brighter than 99 percent of the current Earth orbit. Patrick Seitzer, an astronomer at the University of Michigan who studies space junk, said. The Starlink satellite is brighter than the satellite at the same altitude, he said, “thanks to the design and positioning of Starlinks.”
In the long run, this will affect our perception of the universe, produce more space junk, and the clean night sky we deserve will cease to exist. Johnson said it wasn’t the 19 satellites that destroyed the entire space observation that night, “and we’re afraid it’s going to be the new normal, and if it’s thousands of satellites, it’s bad.”
Some worry that it is too late to regret.
What will the night sky look like in the future?
Such a large satellite deployment could narrow the gap in Internet services around the world. Successful implementation of projects such as Starlink will help connect the world’s most remote and poorest places to the world, thereby facilitating its economy and global connectivity. It’s a revolution. The world will be connected like never before.
Such systems can also work in the event of a natural disaster. For example, when a hurricane destroys communications facilities on the ground, rescue teams can also get real-time messages over the space network.
But there must be a loss.
Astronomers point out that at sunset and sunrise, they are visible to the naked eye when these satellites reflect the most sunlight. If the number of satellites reaches 50,000, they calculate, “you’ll see the whole sky moving slowly.” Tony Tyson, an astronomer and physicist at the University of California, Davis, said, “Satellites can be seen moving in almost every side of the sky. “
Starlink satellites were most visible after their launch, when they were closer to Earth and closer to each other. But over time, these satellites will move toward higher orbit, where they will become less visible and will be dispersed.
Tyson says that when they reach the final orbit, at dusk and dawn (after sunset and before sunrise), “they can still be seen by the naked eye in dark places.” But “the dusk and the dawn” may mean almost the whole evening. It depends on your latitude and time, he said.
You may not be new to the problem of light pollution. Most people who live in or around the city see no stars – except for the brightest ones, most of them are obscured by the city lights.
But light pollution doesn’t apply here, and we’re talking about sky pollution. “The problem is no matter what the region, it’s going to be like that.” Johnson said.
Beyond that, too many satellites can cause other problems, and space debris is one of them. Once the satellite fails, it will float in space until gravity pulls it back to Earth. In fact, several Starlink satellites have stopped working, hovering around the Earth and turning into space debris that could collide with other objects in space at any time.
“If you launch 10,000, 20, 000 or 30, 000 satellites, you’ll automatically create hundreds of pieces in an instant. Christopher Johnson said. He is a space law consultant at the Secure World Foundation, a nonprofit organization that advocates for the sustainable and peaceful use of space. The more space debris in orbit, the more difficult it is to build and operate equipment there.
Important astronomical observations or influenced by satellites
Starlink and other satellites in similar projects are different from other satellites in orbit , the former very close to Earth, which in some way has caused problems for astronomical research. Tyson explains that when you’re 2 times lower in orbit, you’ll be four times brighter on the ground.
The telescope obtains images of the sky from a highly sensitive camera. The satellite is too bright to over-expose the camera’s sensors. The effect is like holding an eraser on an image of the night sky they take, covering the image with a large amount of useless data.
In addition to his work at the University of California, Davis, Tyson is the chief scientist of the Large Sky Telescope (LSST). It is an observatory under construction in Chile and has a wide field of view: it will be able to cover areas in the sky 40 times the size of the full moon and capture objects less than 10 million times the visibility of the human eye.
Starting in 2023, the $500 million LSST will monitor the entire night sky for 10 years, providing scientists with vast amounts of data to help them answer some of the most pressing questions in the universe. This will show the motion of the universe, capturing the evolution of millions of stars.
But if there are thousands of satellites in orbit, LSST’s cosmic horizons will be obscured. “What we’re seeing is a strip. Tyson said.
SpaceX says it has been working with scientists in the astronomical community, particularly LSST, to alleviate the problem.
In one experiment, the company added a black coating to the bottom of one of its newly launched satellites to see if it could mitigate the impact on the telescope’s field of view. But that doesn’t guarantee it’s going to work. If SpaceX can darken the satellite by 100 times, Tyson says, “I believe it’s enough for our software.” “
But simply painting a satellite with a layer of black paint is not easy. Too dark, satellites will begin to absorb excess heat, which may affect their function. It is not clear how much SpaceX will eventually dim the satellite’s brightness. As SpaceX President Gwynne Shotwell told reporters in December, the company is “trying and making mistakes” over and over again.
Tyson is not optimistic. “I don’t hold out any hope,” he said. “I don’t expect them to dim even nearly 100 times. “
Lack of legal protection
Astronomers are so pessimistic because their research has no national or international legal protection.
Simply put, “there are no regulations or guidelines on satellite brightness,” Seitzer said. “Not at the international level, nor at the national level. “
SpaceX may be willing to work with the scientific community to reduce the brightness of its satellites. But in another country, another company, things may be different.
There are astronomical regulations in the United States enforced by the Federal Communications Commission (FCC) and enforced internationally by the United Nations International Telecommunication Union, but they are primarily related to the use and purpose of telecommunications and electromagnetic spectrums, ensuring that satellites do not collide with each other, but do not regulate the appearance of satellites.
“We have learned from the media that there are some concerns about the impact of the Starlink satellite on optical observations by astronomers,” FCC spokesman Will Wiquist said in an email. He acknowledged that “the FCC has not addressed this issue in any of the proceedings.”
In radio astronomy, scientists observe the night sky at frequencies that are invisible to the naked eye, and some of the wavelengths they use are protected by law, and communications companies are inviolable and disruptive. But as Caitlin Casey, an astronomer at the University of Texas at Austin, points out, radio astronomers like to observe all wavelengths outside the scope of protection. So the success of their observations also depends on whether companies like SpaceX are willing to turn off satellite launchers on their large radio observatories.
If you don’t turn off the satellite, “it’s like trying to see fireflies near the sun.” Casey said. In the world of radio astronomy, a satellite that provides Internet connectivity to earth is like a floodlight.
However, radio astronomers have at least readily available channels to express their concerns about radio use, and optical astronomy, which studies cosmic visible light, has no international protection.
The United Nations Outer Space Treaty, which is used for the management of global space use, has made no mention of the reflectivity of satellites and their impact on astronomy. Christopher Johnson explains that even if one country begins to strictly protect the night sky from overcrowding, another country may ignore the rules completely.
Mark Skinner, an astronomer at the International Institute of Space Law, said it was a “neglected problem.”
The future without regulation may become strange.
Without stricter regulation, the future may become even more strange. People can launch satellites to intentionally attract global attention. In January 2018, a New Zealand company launched a satellite called the Star of Human Nature. It’s basically a disco ball in near-Earth orbit. Its creators hope to “create a shared experience for everyone on Earth” through the satellite’s light. Many astronomers are not happy, they liken it to “space graffiti”.
This “star of human ity” may be just a prelude, after which we will be greeted by a larger, brighter night sky. Wired magazine reported that there is no explicit international ban on space advertising. The huge night sky is visible to everyone and is a perfect natural billboard.
“We have enough motivation to sound the alarm and try to make more people aware of the problems that satellites can cause,” says Johnson of Northwestern University. “What is happening is just the tip of the iceberg. “
Once the problem is understood by more people, astronomers may be able to persuade the world to work together to protect a clean, clear night sky. But the worry is that, ultimately, commercial interests will prevail over scientific ones. SpaceX “may be interested in solving the problem, but they’re still a company and they still need to make money.”
Many astronomers do not deny the value of projects such as Starlink, where there are too many places in the world that are not connected to the Internet. The American Astronomical Society recently convened a working group to try to address the problem. “Starlink’s goal is to provide global Internet services that we don’t want to stop,” wrote Kelsie Krafton of the Working Group. “But we don’t want to give up the opportunity to make optical observations from the ground. “
In addition, the impact of changing the night sky will probably go beyond science or the Internet. Looking at the night sky from a dark place, it represents the ultimate wilderness – a primitive natural landscape that humans have barely touched. So what will such a change mean?
“The cultures of the past and the present … have been the cultureof of the past and the present. The night sky is highly valued, many of which have extraordinary and even practical stargazing traditions that have become part of these cultures. Kathryn Denning, an anthropologist at the University of York who studies the ethics of space exploration, wrote in an e-mail. Cultural heritage, she said, “are highly valued at the United Nations, but as far as I know, they have not been translated into satellite protocols”. Even some animals sense direction through starlight, and it’s hard to know whether constellation satellites can also affect them.
Casey, an astronomer at the University of Texas, wants the world to know that disrupting the night sky would cost “humans what they have in the last 200,000, millions of years.” This is not something to be taken lightly.
“My whole love of science and my pursuit of it as a profession goes back to my childhood,” she says. That’s when I saw the night sky and was captivated by it. Astronomy is a unique science, and we can’t build cars behind closed doors in the lab. Our whole science is looking up at the sky, and it will be a tragedy to lose it. “