星链宣布：史上最大降轨行动

Core Viewpoint - The article discusses the increasing congestion in low Earth orbit due to the rapid growth of satellite numbers, highlighting SpaceX's initiative to lower the altitude of its Starlink satellites to mitigate collision risks and reduce space debris [4][5]. Group 1: SpaceX's Initiative - SpaceX plans to lower the altitude of approximately 4,400 Starlink satellites from about 550 kilometers to around 480 kilometers to create a safer operational environment [5]. - This altitude adjustment aims to facilitate quicker deorbiting of satellites in case of anomalies, thereby reducing the generation of space debris [4][5]. Group 2: Solar Activity and Orbital Decay - The altitude reduction is also linked to solar activity cycles, which affect the density of the upper atmosphere. The next solar minimum is expected in the early 2030s, leading to prolonged orbital decay times for satellites at higher altitudes [5]. - By lowering the altitude, the orbital decay time can be reduced from potentially over four years to just a few months, increasing the decay rate by over 80% [5]. Group 3: Risks of Space Congestion - The article notes that low Earth orbit is becoming increasingly crowded, with SpaceX adding over 3,000 satellites through 121 launches last year, averaging one new satellite every three days [6]. - The World Economic Forum predicts a 190% increase in the number of low Earth orbit satellites over the next decade [6]. Group 4: Collision Risks and Kessler Syndrome - The proliferation of satellites raises the risk of collisions, which can create debris that threatens both active satellites and future space missions, potentially triggering the Kessler Syndrome [7][8]. - Kessler Syndrome refers to a scenario where space debris reaches a critical mass, leading to cascading collisions and making certain orbits unusable [8].