Astronomers are struggling to find the quietest, darkest corners that can see the pure night sky. This is why large telescopes are placed in remote areas of the earth, such as the foothills of the Chilean Andes or the summits of Hawaii, rather than near bustling cities, so the large amount of light pollution produced by cities can affect astronomical exploration. For astronomers, a new generation of satellites could be a nightmare as they try to get rid of these urban light pollutions.
Universal Internet access
Since the Soviet Union successfully launched its first man-made satellite, Sputnik, in 1957, manhasion has now launched thousands of satellites of all sizes into the sky for various missions. Thanks to these satellites, we have access to modern weather forecasting, environmental monitoring and reliable mobile Internet.
If there were about 5,000 satellites in near-Earth orbit, only about 2,000 were active. But that is about to change a lot. In March, SpaceX launched 30 StarLink satellites into near-Earth orbit, followed by another 60 earlier this month, meaning the current total in near-Earth orbit is 120.
According to the company’s future development plan, the company will launch up to 42,000 satellites to connect billions of currently unconnected users around the world. SpaceX hopes to offer the service in the northern U.S. and Canada by 2020, before rapidly expanding to a densely populated global reach by 2021.
There is no doubt that network coverage is a very ambitious goal for users worldwide. Internet connectivity is a huge driver of economic growth and has dramatically changed people’s lives on a personal level by providing access to online education, health care and financial instruments. And SpaceX isn’t the only company to embrace the idea.
Back in 2013, Facebook launched Internet.org in partnership with technology giants such as Nokia, Samsung and Ericsson. Led by the social networking giant, the alliance is trying to extend broadband to the ground with large solar drones, allowing those who don’t have access to the Internet to enjoy the conveniences of the Internet. Google is also using the Project Loon project to try to implement similar ideas using high-altitude hot air balloons.
Among the technology solutions championed by the tech giants, companies such as SpaceX and Amazon have taken aim at space, trying to provide network coverage via satellite. Amazon’s Kuiper project also plans to create a similar broadband beam satellite cluster, while OneWeb is another company working to build a broadband satellite network for the entire world.
Photo by SpaceX
Instead of relying on existing, more sophisticated technologies, SpaceX has explored the creation of satellite broadband services earlier than these companies and attempted commercialization through low-Earth orbit. In an interview with Time in May, Elon Musk, the company’s chief executive, said:
I think the star chain is a way to help SpaceX develop more advanced rockets and spacecraft. It also provides security for future self-sustaining cities on Mars and bases on the moon.
Light pollution and potential collisions
This is not to say that the satellite has not been seen in astronomers’ observations before. But SpaceX’s sheer number of satellites, along with the strategic layout of other satellite companies, predicts that near-Earth orbit will become very crowded in the future. And that makes astronomers feel very uneasy.
Following the first 60 star-chain satellite launches, the International Astronomical Union said in a statement issued in June:
The rapid increase in the number of these satellites, which may eventually exceed the number of all visible stars in the night sky, may have a “significant negative impact” on ground and space astronomical observations, including serious damage to optical and near-infrared observations due to reflection and luminescence, which affect radio astronomy observations due to electromagnetic radiation in the satellite communication frequency band, and the risk of collision with space telescopes.
While satellite Internet projects may have good intentions, they not only affect astronomical observations, but also have human implications for the destruction of the night sky, and the International Astronomical Union calls on all parties concerned to explore solutions.
Geoffrey Hall, chairman of the American Astronomical Society’s Committee on Light Pollution, Radio Interference and Space Debris, said the natural night sky is not only a resource for astronomers, but also for all those who look up to the stars to understand and experience the universe, and that the negative effects of the destruction of the night sky go beyond astronomy, and we look forward to strengthening cooperation among all parties concerned to try to reduce the negative effects.
Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Canada, tweeted on November 23
For astronomers, Elon Musk’s SpaceX Starlink is like watching the finale of “Game of Thrones” when someone sneaks into your living room with a can of fireflies and releases them.
Everyone, including SpaceX and astronomers, wants star-chain satellites not always to shine. After reaching near-Earth orbit, these satellites will gradually fly to higher orbits 550 kilometers (340 miles) above Earth. And observations at this altitude through astronomers’ telescopes are, at least not as obvious to the naked eye. But when all 42,000 satellites are launched in the next few years, that’s another scene.
An astronomical map taken by Lowell Observatoryy when the star chain passed
In an explanation for the new Atlas, planetary astronomer and researcher at the National Science Foundation, Stephanie Hamilton said:
These starchain satellites are really bright. While it’s really bright, they’re trying to lift their tracks and become less visible, but they’re not completely invisible. These satellites in particular interfere with sunsets and before sunrise, and these two periods are the best time to conduct scientific research, especially in the search for near-Earth asteroids that pose a potential threat to Earth.
In addition to the need to avoid catastrophic collisions with space rocks and the Earth, star-chain satellites may also need to avoid as many other types of collisions as possible. Tens of thousands of pieces of debris currently rotate on Earth at speeds of more than 20,000 km/h (12,000 mph), consisting of blown-up rockets, large pieces of broken satellites and disappearing spacecraft.
As things stand, this is already a major problem. Large space agencies like NASA and ESA, as well as different research groups around the world, are dreaming of ways to solve the huge problem of space junk, and this has proved to be a daunting task.
So how difficult is it to monitor space debris and satellites in near-Earth orbit? Take a look at the events that took place at the EsA Aeolus satellite in September, so you can see the dangers that star-chain satellites may encounter.
Currently, the tracking is carried out by the 18th Space Control Squadron, a branch of the U.S. Air Force, whose computer systems are at best outdated.
Computers receive input from radars and telescopes around the world and send e-mail alerts about possible collisions. Everyone with e-mail knows that e-mail can be easily lost.
In fact, this has happened since Starlink’s first launch – in the summer, one of the satellites collided with a European Space Agency satellite at a higher than acceptable level, and SpaceX missed the alert email, so ESA had to move its satellites.
SpaceX attributed the error to an error in its paging system that prevented Starlink operators from taking evasive action and said it had since investigated and taken corrective action. The company’s Starlink project website, which documents the space debris problem, reiterated its handling by email.
With comprehensive space safety features – automatic collision avoidance, sharing high-fidelity tracking data with all other satellite operators, and responsible derailment plans – Starlink is a leader in all regulatory and industry standards in meeting or exceeding the mitigation of in-orbit debris.
Patrick Treuthardt, an astrophysicist at the Natural Science Museum in North Carolina, said:
SpaceX is currently the only company to launch satellite constellations, but that may not be the case in the future. Their 42,000 satellites are already tracking a large number of objects in orbit. If others follow suit, it can cause problems. Donald Kessler, a NASA scientist, has come up with a solution called the Kessler effect. The idea is that if the density of objects in orbit is high enough, a collision could trigger a cascading effect on the debris, which could make a range of orbits difficult to use for some time.
The launch of an additional 42,000 satellites into near-Earth orbit is not only a long-standing problem for astronomers, but also a bigger problem with the full launch of 42,000 star chains. Although only 120 satellites have been launched, they have had a significant negative impact on astronomical exploration, as we can see in the motion picture below.
When you’re given the right to look with a large telescope, you’ll find you can’t find what you want. You must be very efficient in allocating time. You may need to spend the night collecting long exposures for individual objects so that you see details that no one has previously observed. If a satellite happens to enter your field of view and reflect sunlight in one of your exposures, it can seriously interfere with the target you are observing. And this is incurable, and you will lose this precious time.
The satellite in the astronomical image appears as a stripe through the image. Many astronomical observations involve repeatedly taking images of the same sky area, which makes it easier for astronomers to filter out false differences between images. However, doing so increases computing costs and makes data processing more complex. In addition, the Starlink satellite’s brightness is particularly dazzling, which can easily overwhelm our very sensitive detectors. When this happens, the software correction is no longer sufficient – a bright satellite can cause other artifacts in the image that we can’t correct.
In addition to affecting the various types of light that astronomers collect, star-chain satellites can also affect things they can’t see. The focus of radio astronomy is to collect radio waves that travel through the universe and to convert these signals into invaluable discoveries. Rapid radio bursts, for example, have recently become one of the most fascinating mysteries of modern astronomy. There are concerns that the radio frequencies used by the Starlink satellite will make the process more difficult.
Radio astronomers have had to contend with a highly radioactive planet for observation. Very few radio frequencies remain unpolluted, and these giant constellations have the potential to erode them and wreak havoc on Earth radio astronomy.
So where to start?
SpaceX has addressed the concerns of radio astronomers and said by e-mail that it has actively coordinated with the European Radio Astronomy Community and the National Radio Observatory (NROA) so that we can work together to protect important radio astronomy activities.
This could mean defining a no-go zone for star-chain satellites, or a minimal impact on the working position of a radio antenna. SpaceX said it was “actively working with leading astronomy teams around the world to ensure that its work is not affected” and was taking steps to “blacken the base of the Starlink satellite.”
SpaceX has begun working with the astronomical community to reduce the reflectivity of its satellites, which will make them darker. I am indeed encouraged, but as far as I know, there have been no reports on when such satellite changes will be included in the report. I want to have more communication with SpaceX in that regard.
Another problem is how satellites can become less shiny, but not all of the needs of the community. “I read a comment on Twitter that said that the starchain satellite had been painted vantablack,” Says Treuthardt. This can alleviate the telescope’s observation in the visible part of the spectrum, but it does not help much in near-infrared observation. “
SpaceX has all the indications that it is listening to concerns about its Starlink project and has been around for some time. But it is clear that meeting the needs of the astronomical community while putting thousands of satellites into orbit will be a daunting task.
The thorny question is what steps should be taken by astronomers and the companies that launch these constellations. I think that the failure to find a simple solution at this stage will satisfy both sides. Ideally for astronomers, there would be no large number of reflectors in orbit, or they would be “invisible” at the wavelengths and frequencies observed by astronomers. I don’t think this is a viable solution.