Reference Message Network reported on June 9 that according to a report from the website of Komsomolskaya Pravda in Russia on June 8, satellites launched by SpaceX, Elon Musk's space exploration technology company, have been falling one after another. A research team led by physicist Danny Oliveira from NASA's Goddard Space Center studied the "satellite rain".

SpaceX first launched the Starlink satellites in 2019, and some satellites fell in 2020. However, given the large number of "Starlink" satellites launched by Musk, the initial number of fallen satellites was still within a reasonable range. Only two satellites fell in 2020. But in 2021, the number of fallen satellites surged to 78. In the following two years, the number of fallen satellites remained at this level (99 satellites fell in 2022 and 88 satellites fell in 2023). However, last year something strange happened: 316 satellites burned up in the atmosphere. By now, a total of 583 satellites have been lost in the "Starlink". About one out of every 15 satellites has fallen. What happened?

The research team compared the time of satellite falls with various natural phenomena and found a clear correlation between satellite falls and solar activity.

The research report pointed out: "We clearly found that the current increase in solar activity has a significant impact on the "Starlink" satellites falling into the atmosphere. This is an excellent period for studying satellite orbital resistance because during this solar activity peak, the number of low-orbit Earth satellites has reached the highest level in human history."

The launch of the "Starlink" satellites began in 2019 when it was at the low point of the solar activity cycle. NASA statistics show that last year was the peak of solar activity.

The solar activity cycle is about 11 years. When many sunspots appear on the surface of the sun, strong explosions and solar flares occur. Solar winds are ejected through coronal holes, and part of the material flies towards the Earth, causing magnetic storms. When the solar plasma reaches the Earth and triggers magnetic storms, another effect occurs - a heating phenomenon of the upper atmosphere. The atmosphere heats up and expands, and satellites experience greater flight resistance, eventually deviating from their orbits and falling.

Since "Starlink" satellites need to provide communication services, they are at a relatively low orbit. It is estimated that the average life span of satellites in this orbit is five years.

Although this phenomenon can be understood overall, there are still many mysteries. For example, the research report points out that 70% of the satellites did not fall during strong magnetic storms but fell during moderate and weak magnetic storms. This is likely because weak magnetic storms usually last longer and slowly "erode" the orbit, pushing the satellites toward an inevitable end. (Compiled/ Zhao Zhipeng)

Original article: https://www.toutiao.com/article/7513822927914091047/

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