After the launch of a module of the Chinese space station, the crash of the 20-ton rocket stage was filmed near a populated area. A piece of space debris weighing more than 20 tons fell uncontrolled into the earth's atmosphere around 7 p.m. Central European Time on Saturday. The debris narrowly missed inhabited area and fell off the coast of the Philippines into the Sulu Sea - a tributary sea slightly smaller than the North Sea. The crash was observed over the island of Borneo, shared between Indonesia, Malaysia, and the Sultanate of Brunei.
The parts were the main rocket stage of the Long March 5B rocket, which previously launched the second module, Wentian, of the Chinese space station. For the sake of reliability and performance, the 5B variant consists only of the core stage and four side boosters. Further rocket stages, which are intended for the regular Long March 5 to achieve higher speeds such as for high orbits or targets beyond the earth, are dispensed with.
The core stage of the 5B, therefore, enters a very low parking orbit together with the payload and separates them there. The core stage of a regular Long March 5 flight, on the other hand, will not reach orbit if its fuel is depleted and the upper rocket stage is separated. At almost 40 tons, this is significantly heavier than a payload such as the 22-ton module of the space station. The core stage of the regular Long March 5, therefore, falls in a controlled manner in the Pacific Ocean, east of the Chinese island of Hainan.
The crash location is almost unpredictable
The core stage of the Long March 5B has no significant fuel reserves in orbit and also no more re-ignition engines so it staggers uncontrollably in Earth orbit after launch until it crashes due to the friction of the Earth's upper atmosphere. Due to the high speed of around 8 kilometers per second and the very small and difficult to determine braking forces due to the atmosphere, the exact location of the crash is practically unpredictable.
NASA boss Bill Nelson called on the Chinese government to provide at least as detailed information as possible on the rocket stages in order to make better predictions possible to warn the population.
The Ariane 5, which is comparable to the Long March 5, used an additional smaller rocket stage with restartable engines when launching the ATV transporter to the ISS. As a result, the large core stage could be separated before reaching orbit and crash into the Atlantic in a controlled manner, and the smaller rocket stage could also be disposed of in a controlled manner.
While uncontrolled crashes of rocket stages or entire space stations cannot always be avoided, as in the case of Skylab or Salyut-7, these are malfunctions. With the Long March 5B, on the other hand, the uncontrolled crash is unavoidable, which represents a serious danger with such large rocket stages, because several large and heavy pieces of debris always reach the earth's surface. It would greatly help China's space reputation to avoid such dangers.