A “low” or even “tiny” risk, but not zero: a Chinese rocket must make its uncontrolled return to the Earth's atmosphere this weekend, China and many experts, however, deeming the hypothesis of damage on Earth to be minimal.
The Asian country placed the first module of its space station in orbit on April 29, thanks to a Long-March 5B carrier rocket, the most powerful and imposing Chinese launcher.
It is the first stage of this rocket, currently in orbit, which must return to Earth.
It is gradually losing altitude and its point of fall is currently unknown.
China is very discreet on this issue and has not published any forecast on an hourly potential for the launcher to return to Earth's atmosphere, where it should totally or partially disintegrate.
For the Russian space agency Roscosmos, the entry could be made at 1:30 in the night of Saturday to Sunday (French time) at the level of the south of Indonesia.
The US Department of Defense is counting on 1 a.m., with a margin of error of nine hours on either side of this estimate.
The window should gradually thin out over the hours.
China ended up reacting to try to reassure
After a long embarrassed silence from the Chinese space and diplomatic authorities, Beijing finally reacted on Friday.
"The majority of components (of the rocket) will be burned and destroyed when re-entering the atmosphere," said Wang Wenbin, a spokesman for the Chinese Ministry of Foreign Affairs.
"The probability of causing damage to air activities or (to people, buildings and activities) on the ground is extremely low," he said.
The Chinese media provided minimal coverage of the event on Saturday, contenting themselves with repeating the remarks made the day before by the spokesperson for diplomacy.
If parts of the rocket remain intact after re-entering the atmosphere, there is a good chance that they will be damaged at sea because the planet is 70% water.
"We hope they land in a place where they do not harm anyone," said Friday Mike Howard, a spokesman for the US Department of Defense, stressing that the United States was following the rocket.
US Defense Minister Lloyd Austin assured this week that his country had no intention of destroying the rocket.
He hinted, however, that its launch was not planned with enough care by China.
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The risk of heavy launcher debris hitting a populated area exists, but is unlikely.
"Given the size of the object, there are necessarily large pieces that will remain," anticipates Florent Delefie, astronomer at the Paris-PSL Observatory.
But the probability of an impact on an inhabited area is "tiny, less than one in a million, undoubtedly", reassures Nicolas Bobrinsky, head of the Engineering and Innovation department at the European Space Agency (ESA).
In 2020, debris from another Longue-Marche rocket crashed into villages in Côte d'Ivoire, causing damage, but no injuries.
In April 2018, China's Tiangong-1 space laboratory disintegrated when it entered the atmosphere, two years after it ceased to function.
A Chinese robot on Mars in the coming weeks
China has been investing billions of euros in its space program for several decades.
The Asian country sent its first astronaut into space in 2003. In early 2019, he landed a machine on the far side of the Moon - a world first.
Last year, he brought back samples of the Moon and finalized Beidou, his satellite navigation system (competitor of the American GPS).
China plans to land a robot on Mars in the coming weeks.
She also announced that she wanted to build a lunar base with Russia.