SpaceX 330,000 satellites attracted controversy from all sides.

SpaceX 330,000 satellites attracted controversy from all sides.

SpaceX3' s30,000 satellites have attracted controversy. As of last year 165438+ 10, the number of satellite chains that have been launched has reached 179 1, and the total number of satellites planned for the whole satellite chain is 42,000. SpaceX3' s30,000 satellites have caused controversy.

The 30,000 satellites of Space Exploration Technology Company caused controversy. 1 Ask the world's most famous private aerospace company. The person that most people know must be the space exploration technology company.

The name of space exploration technology company is very short, and its full name is space exploration.

This company has a good reputation, but its reputation in the whole space exploration field and industry is getting worse and worse. ...

why ...

As a private space company with the strongest launching capability in the world, Space Exploration Technology Company almost single-handedly undertook a large number of launching tasks by governments and private companies in many countries in the world, such as the United States. Even the U.S. government has packaged the previous "state-owned" launch pad resources and handed them over to space exploration technology companies for operation.

Without this company, space exploration will lose an important carrier supplier. It stands to reason that everyone should respect the value of space exploration technology companies, but in the eyes of some space observers, space exploration technology companies are simply "chaotic."

In their photos taken from observing space, more and more satellite chains of space exploration technology companies are "stealing mirrors".

Recently, scientists from many astronomical observation institutions around the world jointly published a communication paper complaining about the chaos caused by the satellite link of space exploration technology company. The article points out that in recent years, the proportion of observation photos polluted by satellite chain has accounted for nearly 20% of the whole photo library, which has increased by 35 times.

First, always grab the camera at the critical moment.

Scientists from the US government, European Observatory, Warsaw University, California Institute of Technology, University of California, Berkeley and other institutions recently published such a communication paper in the communication column of Astrophysics Journal, the core journal of space exploration: "The Influence of Satellite Link of Space Exploration Technology Company on the Observation Results of Zwedeki Transient Facility".

Remarks: Ztwick Transient Facility (ZTF) is a special observation facility for observing transient astronomical events. It is located at the Palomer Observatory in San Diego, Southern California, and is operated by California Institute of Technology. Transient astronomical events refer to astronomical events with short duration (several seconds to several years), such as gravitational wave events and gamma ray bursts.

Scientists extracted a large number of astronomical photos taken by ZTF from September 20191to September 20021and analyzed them, and found such a worrying problem:

In the past two years, there have been more than 5300 satellite tracks in ZTF observation photos.

The picture below, released by California Institute of Technology, shows the results of shooting Andromeda galaxy by ZTF telescope in May last year. It can be seen that a long and bright trajectory line directly passes through the photo, which has caused significant pollution to the observation subject.

Image source: California Institute of Technology

It is worth noting that the figure only shows the field of view of116 and ZTF up to 47. On the whole frame, the orbit pollution is more.

Scientists also found that with the space exploration technology company speeding up the satellite chain plan, the number of satellites in orbit has increased rapidly, and the proportion of pollution caused by these satellites to ZTF observation results has also increased significantly.

At the end of 20 19, only 0.5% of the twilight observation photos of ZTF were polluted by the satellite trajectory of the star chain.

By August of 20021year, the proportion of polluted photos increased by 35 times, reaching about 18%.

In the figure below, the red line is the number of satellites in orbit of Space Exploration Technology Company, and the blue column is the number of ZTF pollution photos in the same period:

In particular, the author mentioned that the existence of a large number of satellite chains in near-earth orbit has caused serious pollution to low-light-level observation.

Astronomical twilight refers to the sunlight scattered from the upper atmosphere to the lower atmosphere in the early morning and evening when the sun is below the horizon 12 to 18. At this time, the sky is no longer illuminated by the sun, which is convenient for observing some key celestial bodies, and even some celestial bodies can be seen by the naked eye.

The short twilight period is very important for the discovery and observation of near-earth objects. Near-Earth objects may include comets, meteors and celestial bodies that pose a potential threat to the Earth. In 2020, there is an asteroid with a diameter exceeding 1km, and its orbit is completely within the orbit of Venus, which was discovered by ZTF in the twilight period-these observation activities are very important for protecting the earth and life on it.

The twilight period happens to be the most serious period of satellite pollution astronomical observation in the star chain.

The author points out that the projection plane density of satellite chains is the highest near the horizon and at dusk, which has a disproportionate impact on astronomical observation.

The author also quoted other scientists' model deduction: about 90% of the observable satellites in low earth orbit will gather in the sky near the ground plane (within 30). Due to the refraction and reflection of solar light, the brightness of these satellites has been obviously improved, which interferes with the astronomical observation in the low light level period. Their brightness will only decrease for a long time after sunset/before sunrise.

At present, the satellite chain is the largest system among all satellites in low-earth orbit and has become the first pollution source of low-light-level astronomical observation. Therefore, many ground astronomical researchers and observation enthusiasts expressed their dissatisfaction with Space Exploration Technology Company.

However, the author of the paper also said: as far as the ZTF family as a data source is concerned, its normal scientific observation activities have not been particularly significantly affected by the pollution of the star chain trajectory.

However, considering that Space Exploration Technology Company has been approved by the FCC, the US communications regulator, to launch more satellites, if the total number of satellites in the future satellite chain network really increases to1.2000 (seven times the current number), the consequences are really unimaginable.

The author estimates that when the number of satellites in the satellite chain system reaches 654.38+00000, all the astronomical observation photos of ZTF will be polluted by the orbit of satellites in the satellite chain-note that not all photos, that is, the pollution ratio will be 654.38+000%.

Needless to say, on the basis of the current plan of 65,438+200,000, Space Exploration Technology Company also submitted a new plan to the US government, which will launch an additional 30,000 satellites. By then, all ground observations of space will inevitably be polluted.

To exaggerate, the existence of many satellite chains will bring greater obstacles to human beings in discovering and preventing the threat of near-earth objects.

The trajectory of the satellite chain appears in the infrared photos of space observation. Image source: NASA Observation Laboratory.

Second, space exploration technology company did not try to correct it.

2065438+In May 2009, Space Exploration Technology Company launched the first batch of satellite chains. At that time, the astronomical community had expressed concern about the pollution caused by a large number of satellites in low earth orbit.

However, considering that FCC, the federal communications regulatory agency affiliated to Star Chain, has more real power, and space exploration technology companies have a high voice in the aerospace industry, these concerns have hardly hindered the promotion of Star Chain. In addition, the Federal Communications Commission has repeatedly approved the plan of Space Exploration Technology Corporation to increase the number of satellites in the satellite chain.

If readers have seen the movie Don't Look Up at Netflix recently, they should remember how those in power and technology tycoons despise the opinions of astronomical experts. Now it seems that this plot is not a fictional satire, but a depiction of reality ...)

Don't Look Up stills Image source: Netflix

As mentioned in the article, by the end of last year, the number of launched satellite chains had reached 179 1: 124 satellites had fallen into the atmosphere and retired, and the number of satellites in orbit had reached 1667, and the number of satellites in normal operation (which can provide Internet services for the ground).

The number is still growing rapidly, because every time a space exploration technology company launches a satellite chain, it is not a satellite, but it can be launched in batches. The number of each batch is usually between 48 and 53 satellites, and the maximum load of Falcon 9 rocket of space exploration technology company is 60. Only the first two launch missions of Space Exploration Technology Company this year will increase the number of satellite chains in orbit to nearly 2,000.

According to the plan disclosed by Space Exploration Technology Company and submitted to the regulatory authorities, the total number of satellites in the entire star chain plan is 42,000.

Satellite chain superimposed launch load mode Image source: Space Exploration Technology Company

As the absolute leader of today's private space industry, space exploration technology company inevitably has to deal with the whole astronomical research group in the process of continuous operation and growth.

In fact, the company has also made some efforts to minimize the visibility of satellite links in the sky and reduce the impact of their existence on astronomical observation on the ground.

In April 2020, Space Exploration Technology Company published a document on its official website, saying that it had held talks with experts from the National Academy of Sciences on the interference of satellites with astronomical observations. The company said that the satellite chain to be launched in the future will be technically transformed, with a dark coating and an inflatable mask installed in the brightest part of the satellite, thus reducing the albedo of the satellite in astronomical observation.

Starting from 20 19, 1 1, Space Exploration Technology Company began to adopt the satellite chain version of V 1.0 (although the version number is 1, it is not the first satellite version launched by Space Exploration Technology Company). One of this generation of satellites is called DarkSat, which uses a special dark coating on the surface of the shell to reduce the albedo.

Unfortunately, this coating was later found to cause satellites to absorb excessive visible radiation and reflect excessive infrared rays, leading to serious overheating problems. As a result, the dark satellite program was soon abandoned.

A few satellites in the V 1.0 series, and the satellites in the subsequent V 1.5 series, have added a dark cover (see the figure below) that can be unfolded, unfolded and retracted to replace the failed coating scheme named VisorSat. In principle, these masks can be deployed during the period when satellites have the greatest influence on astronomical observation, and then retracted after the period.

The aforementioned communication paper pointed out that this scheme of using masks has obvious effect on reducing the visibility of satellites in key periods. However, due to mechanical failure, some recently launched satellite chains are not equipped with masks, or they are installed but not deployed.

Space Exploration Technology Company announced in official website that it is cooperating with some well-known astronomical associations and research institutions to further explore the influence of satellites on astronomical observation and deploy solutions in time.

However, from the observation data provided by the communication paper published in June 5438+this year1October, the efforts of Space Exploration Technology Company have no actual effect-on the contrary, while the problem has not been solved, Space Exploration Technology Company continues to increase the number of satellites in orbit. Just last Thursday, February 4th, Space Exploration Technology Company just launched the second batch of satellite chains this year, with a total of 49 satellites.

"In view of the increasing number of satellites in orbit, the number of observation photos affected by their trajectories is also worrying," the paper wrote. "We will continue to observe the sky in the northern hemisphere and expect to record thousands of additional satellite tracks."

The 30,000 satellites of Space Exploration Technology Company caused controversy. It is reported that the National Aeronautics and Space Administration (NASA) is worried about the plan of Space Exploration Technology Company to deploy about 30,000 satellites for its "Star Chain", and some big companies are also worried about this matter.

Elon musk's space exploration technology company, Space Exploration Technology Company, has been authorized to deploy about1.2000 satellites to provide users with broadband Internet services, and has requested authorization to build a second-generation satellite constellation consisting of 30000 satellites.

In the report of the Federal Communications Commission, NASA wrote: "NASA is worried that the frequency of related events may increase significantly and may have an impact on NASA's scientific and manned space missions."

According to NASA, the total number of objects tracked in orbit is 25,000, of which about 665,438+000 are below 600 kilometers. The report pointed out that the expansion of the second generation (Gen2) constellation of Space Exploration Technology Company "will more than double the number of tracked objects in orbit and increase the number of objects below 600 kilometers by more than five times."

Jonathan McDowell is an astrophysicist at Harvard Smithsonian and a member of the research group on the influence of satellites on astronomy of the American Astronomical Society. He said, "We have been worried that a large number of satellites will interfere with astronomical observation ... I think we need to accumulate more experience in operating thousands of satellites before we can gradually increase the scale to tens of thousands of satellites."

Space Exploration Technologies did not immediately respond to a request for comment.

On June 5th, 65438+ 10/kloc-0, Musk tweeted that 1469 satellite chains of Space Exploration Technology Company were active and 272 satellites were about to enter orbit.

Amazon (Amazon.com) has promised to spend at least $654.38+0 billion to build 3,236 such satellites through the Kuiper Project. The company and Dish Network respectively raised concerns about the plans of Space Exploration Technology Company to the Federal Communications Commission (FCC).

According to Amazon, according to Space Exploration Technology's application, "at least hundreds of Space Exploration Technology's satellites-even more than 65,438+0,000-can operate at the same altitude as the Kuiper system."

It warned that "the impact of this track overlap will greatly increase the risks and other burdens of the Kuiper system" and asked the FCC to impose "reasonable conditions" on the project.

Although the deployment cost is extremely high, satellite technology can provide high-speed internet services for residents living in rural areas or areas where optical fiber cables and cell phone towers cannot reach. When hurricanes or other natural disasters interrupt communication, this technology may also become a key backing.

According to media reports, the National Aeronautics and Space Administration (NASA) sent a letter to the Federal Communications Commission (FCC) expressing concern about SpaceX3' s second-generation star chain plan.

Elon musk's Space Exploration Technology Company has been authorized to launch about 65,438+2,000 satellites, and has requested the FCC to authorize the launch of the second-generation satellite chain system, and will launch about 30,000 more satellites.

In the letter, NASA wrote that it is worried that with the increase of the number of satellites deployed in the satellite chain plan, the probability of collision events may increase greatly, which will have an impact on NASA's scientific and manned space missions.

According to data quoted by NASA, the total number of objects currently tracked in orbit around the earth is 25,000 (including satellites and all kinds of space junk), and the second-generation satellite chain plan of Space Exploration Technology Company will more than double the number of objects tracked in orbit.

Jonathan McDowell, an astrophysicist at the American Astronomical Society, said, "We have been worried that a large number of satellites will interfere with astronomical observation. I feel that after having more experience in operating thousands of satellites, we should consider upgrading to tens of thousands. "

Musk revealed on Twitter last month that Space Exploration Technologies currently has 1469 satellites in active state, and 272 satellites are about to enter orbit.

Earlier, Amazon, a competitor of Space Exploration Technologies, also expressed similar concerns. Amazon complained to the FCC that the satellites in the star chain can operate at the same height as the Kuiper system (Amazon's satellite project), and the risk of orbital overlap will greatly increase the risk and other burdens of the Kuiper system, and asked the FCC to impose reasonable conditions.

It is worth mentioning that the occurrence of external force majeure events such as solar storms will also bring many hidden dangers to the star chain plan of space exploration technology company.

Space Exploration Technology announced on Wednesday that it launched 49 satellites on February 3, but as many as 40 satellites were lost and burned in the earth's atmosphere due to the solar storm the next day.