Share the news to friends and circles of friends with wechat scanning code QR code < / P > < p > on January 18. The image analysis taken by astronomers at the Sky Survey Telescope confirmed that there are more and more star chain satellite tracks in astronomical observation images. If all SpaceX approved satellites are launched, satellite trajectories of star chain will appear in the observation images of relevant telescopes, which will have a greater impact on astronomical observation at dusk < p > < / P > < p > SpaceX's "star chain" Internet service requires a dense satellite group in orbit to provide low latency network connection services. At present, there are more than 1500 satellites in orbit in the whole star chain system, and the Federal Communications Commission (FCC) has previously approved the launch of 12000 star chain satellites. This worries astronomers. Although SpaceX has taken measures to reduce the impact of satellite operation, it can not completely eliminate the traces left by satellites in ground observation < p > how serious is this problem? In the past two years, astronomers have found that the number of images affected by the orbit of satellites in the star chain has increased 35 times. Researchers estimate that if the satellite chain launches all satellites as planned, there will be at least one satellite track in almost every observation image < p > looking ahead, there are too many < / P > < p > the ground observation facility used by astronomers to analyze this impact is the zweiki transient facility (ztf) of Paloma observatory. Ztf is used to capture rare events such as supernovae in the universe. It repeatedly scans the whole sky and uses software to screen objects that do not exist in early images but appear in later images. The high sensitivity of ztf enables it to well identify asteroids and other darker objects in the solar system < p > ztf mainly scans the whole sky quickly through wide field of view and giant camera, but it also increases the possibility of seeing the satellite trajectory of star chain < p > in order to determine the frequency of the satellite chain captured by the ztf camera, the research team collected the orbit data of all satellite chains and compared them with the sky area observed in each ztf archived image. Once an image is determined to be possible to capture the satellite image of the star chain, researchers will use software to detect whether there are bright tracks in the image. This analysis covers ztf observation images for about two years from November 2019 to September 2021 < p > during this time, SpaceX is rapidly building a star chain network. At first, only about 100 star chains were in orbit. Usually, ztf telescope will not detect a star chain satellite in 10 days of observation. When 500 satellites enter orbit, the period of no satellite chain is shortened. When there are more than 1500 satellite chains in low earth orbit, ztf usually records more than 200 satellites in about 10 days < p > the influence of observation at dusk is the most obvious. The observation angles that capture the horizon will make the satellite trajectories of the star chain occupy more space in the observation image. In addition, the position of the sun at dusk also lights up more satellites. Therefore, about 64% of the satellite trajectories of the star chain are captured at dusk. With the increase of the number of satellites, the number of satellite tracks in the observation images has also increased explosively. At the end of 2020, only about 6% of dusk observation images will be affected. By the end of 2021, this figure will increase to 18% < p > with more and more complaints from the astronomical community, SpaceX has installed a light shield on the new generation of satellite chain satellites. The researchers compared the visibility of different satellite chains and found that the brightness of satellite chains using light shields decreased by about 4.6 times, but the satellite visibility was still higher than the goal set at the problem-solving seminar < p > at present, the satellite track of the star chain in the image is small, and it can be identified and processed by software, so it has little impact on astronomical observation. Researchers estimate that at present, the probability of missing rare astronomical events due to the coincidence with the satellite trajectory of the star chain is only 0.04%. However, because this problem is the most serious in dusk observation, it is more likely to affect Astronomers' search for objects in the solar system such as comets and asteroids. The problem could get worse. SpaceX has been approved to launch more than 10000 satellite chains. When the number of satellites in orbit exceeds 10000, each image taken at dusk may contain a star chain track. SpaceX said it ultimately hopes to increase the number of satellites in orbit to more than 40000, so that all images observed at dusk may contain four satellite trajectories < p > in addition, SpaceX is not the only company planning to provide satellite Internet services. If all companies launch satellites as planned, the telescope will be able to observe up to 100000 low earth orbit satellites < p > the main task of ztf is to find rare events caused by distant high-energy phenomena, which is largely unaffected by more and more satellite trajectories. Since the probability of affecting the observation of rare events is very small, doubling the number of satellites will not have a significant impact on such observation. However, a large number of light pollution events have occurred in other scientific observation missions, and the situation will only get worse. (Chen Chen) < / P > < p >