Just days after the Chang Zheng 5B primary stage made an uncontrolled re-entry into the atmosphere (an event that forced several airports in Spain to close their airspace as a precaution), the upper stage of another Chinese rocket, the Chang Zheng 6A, broke up from a heliosynchronous orbit and created more than 50 dangerous fragments.

The Chang Zheng 6 is an advanced light-caliber liquid-orbital launch vehicle (the first stage has a YF-100 engine running on kerosene and liquid oxygen) used by China to launch small satellites into low Earth orbit. So far, since 2015, the rocket has been used 10 times to launch satellites into low Earth orbit or heliosynchronous orbit (a low Earth orbit that allows it to pass over a fixed point on Earth’s surface at exactly the same time of day).

The upgraded version of the Chang Zheng 6B has a first stage equipped with two YF-100 engines, is equipped with four additional solid-fuel engines and has a larger second stage, making it more powerful than the previous version. A few days ago, on November 12, at 00:52 Romanian time, the Chang Zheng 6A rocket launched the Yunhai-3 meteorological satellite into a heliosynchronous orbit, at an altitude of 700 km. It was the second flight of the 6A version of the rocket, and everything seemed to go well: the satellite detached from the upper unit and contacted the Earth, the mission was successful.

As happens after most orbital launches, the upper stage of the rocket had to reenter the atmosphere in a controlled manner during the next period and burn up completely. Because it is a booster, its engine can usually be restarted, and any deorbit debris can be sent to a desert area in the Pacific Ocean. Neither did the upper stage of Chang Zheng 6B, which probably due to technical problems exploded and produced more than 50 fragments (i.e., orbital debris) that are now between 500 and 700 km above Earth. The event took place on November 12 at 07:25 Romanian time and was confirmed by the US Space Force.

Given the height of the fragments, it will likely take several decades for them to fully enter the atmosphere, and even if they do not currently pose a danger to the International Space Station (ISS), their height will decrease over time and they will end up causing problems for the ISS (which rotates around the Earth at an altitude of about 400 km).

Depending on the density of the atmosphere (and solar activity, which can affect the density of the atmosphere at certain altitudes), orbital fragments may return through the atmosphere sooner or later, but the higher their altitude, the more time it takes to interact with the air, resulting in ultimately unstable orbit.

This is not the first orbital contamination event for which China is responsible: on January 11, 2007, a ballistic missile struck a weather satellite (Fengyun-1C) during an anti-satellite test conducted by the Chinese military, creating more than 2,000 large fragments. more than 5 cm and probably hundreds of thousands of fragments too small to identify. Although their numbers have decreased in recent years, fragments from the 2007 test are likely to remain in orbit until the middle of the next decade and pose a threat to operational satellites or the International Space Station.

China is not the only country that has conducted anti-satellite tests, but it is the country that generates the most fragments of such tests. In 2008, a US ballistic missile hit the USA-193 reconnaissance satellite, which was reportedly experiencing technical problems, creating hundreds of orbital fragments. In March 2019, India destroyed its own Microsat-R satellite, but if we look at the positive side of this test, it is that at least the collision occurred at a relatively low altitude, speeding up the re-entry through the atmosphere of the resulting satellite. explosion fragments.

And we cannot forget the last such test conducted by Russia on November 15, 2021, when a ballistic missile launched from the Plesetsk military cosmodrome struck and destroyed the Kosmos-1408 satellite (which weighed more than 1.7 tons), generating more than 1,500 fragments at an altitude of 300 up to 1000 km, creating danger including for the Russian crew aboard the International Space Station (and the taikonaut crew aboard the Chinese space station).

As a result of this event, on April 19, 2019, US Vice President Kamala Harris announced during a visit to the Vandenberg Space Center in California that the United States was unilaterally abandoning such tests and called on other countries to join this decision. As expected, so far this initiative has been joined by either states that do not have such a capability at all, or states that have never conducted such destructive tests that ultimately affect all orbital activity.

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