The core stage of a Chinese Long March 5B rocket is set to fall uncontrollably back to Earth today in a re-entry that China is watching closely and which it says poses little risk.
The approximately 25-tonne (23 metric ton) rocket stage, which was launched on July 24 to deliver the Wentian lab cabin module to China’s incomplete Tiangong space station, is expected to return Earth atmosphere on July 30 at 12:15 p.m. ET, plus or minus 1 hour, according to researchers at The Aerospace Corporation Center for Orbital Debris and Reentry Studies (opens in a new tab).
It’s unclear exactly where it will land, but the possible debris field includes the United States, India, Australia, Africa, Brazil and Southeast Asia, according to The Aerospace Corporation (opens in a new tab)a US government-funded nonprofit research center based in California.
Related: The biggest spacecraft that fell out of space without control
A rocket’s first stage, its propellant, is usually the largest and most powerful section. Usually, rocket booster trajectories are planned to either avoid orbit and fall harmlessly into the ocean or, if they manage to orbit, perform a controlled re-entry with a few bursts of their engines. But the Long March 5B booster engines cannot restart once they have stopped, dooming the booster to spin around the Earth before landing in an unpredictable location.
This is the third time in two years that China has dumped its rockets out of control. In the second case, in May 2021, the rocket debris landed harmlessly in the Indian Ocean. But the first incident, in May 2020, reportedly rained metal objects on villages in Ivory Coast, although no injuries were reported.
Due to their massive size, Long March 5B boosters can be particularly at risk during an uncontrolled re-entry, which means that a significant portion of their mass does not burn off safely in the atmosphere.
“The general rule of thumb is that 20% to 40% of a large object’s mass will hit the ground, but the exact number depends on the design of the object,” said Marlon Sorge, space debris expert at The Aerospace Corporation. . said in an online Q&A (opens in a new tab). “In this case, we would expect around five to nine metric tons [6 to 10 tons].”
“Typically, for an upper stage, you see small and medium tanks surviving more or less intact, and large engine components,” Sorge added. “The large tanks and the skin of this central stage are susceptible to disintegration. We will also see light elements such as insulation falling off. The melting point of the materials used will make a difference in what remains.
What’s the risk?
According to The Aerospace Corporation, since more than 88% of the world’s population is below the rocket’s orbital footprint, some surviving debris could land in a populated area. But Muelhaupt said the odds of this debris harming someone range from 1 in 1,000 to 1 in 230, and the risk for a single individual is much lower – around 1 in 6 trillion to 1 in 10 trillion. For comparison, he added, the probability of being struck by lightning is about 80,000 times higher. The internationally accepted accident risk threshold for uncontrolled rocket re-entry is 1 in 10,000, according to a 2019 report by the US government’s Orbital Debris Mitigation Standard Practices.
Despite the relatively low risk of harm to life or property, China’s decision to launch rockets without controlled-reentry options has drawn severe rebukes from US space experts.
“Space nations must minimize the risks to people and property on Earth from space object re-entries and maximize transparency regarding these operations,” said NASA Administrator Bill Nelson. written in a statement (opens in a new tab) after the 2021 Long March 5B crash. “It is clear that China is failing to meet responsible standards regarding its space debris.”
“Why are we worried? Well, it caused property damage last time [in 2020], and people need to prepare accordingly,” Ted Muelhaupt, space expert and consultant at The Aerospace Corporation, told a press conference. “It doesn’t have to be. We have the technology to not have this problem.”
China called the concerns “shameless hype.” In 2021, then-Chinese Foreign Ministry spokesperson Hua Chunying accused Western reporting of bias and “textbook-like double standards” in their coverage of the Chinese rocket downfall. For example, in March 2021, debris from a free-falling SpaceX rocket crashed into a farm in Washington state, an event she says Western media covered positively and with use. of “romantic words”.
According to Article VII of the 1967 Outer Space Treaty, to which all major space nations – including China – are parties, any country that sends an object into space is internationally liable for any damage it does. could cause another party when it crashes back to earth. If that were to happen, the incident would be dealt with by a claims commission or dealt with through diplomatic channels – like in 1978, when the faulty Soviet satellite Kosmos 954 crashed in western Canada, shattering about 370 miles of long (600 kilometers). path with debris from its broken onboard nuclear reactor.
Christopher Newman, professor of space law and policy at Northumbria University in London, said all major launch nations will have parts of space objects returning to Earth unchecked, but establishing an international consensus on the How to deal with them is difficult given the current geopolitical tensions.
“This is a problem that requires an international solution, especially since objects such as rocket bodies are three times more likely to impact cities in the ‘Global South,'” Newman told Live Science. “Yet one only has to look at the attitude of countries towards space monitoring and space situational awareness, as well as the problem of debris in Earth orbit, to see that the international community does not is not yet motivated to try to solve this problem.
“As a lawyer, it is clear to me that the impetus for change only comes when there is some form of disaster or tragedy – and by then it is often too late,” said he declared. “The warnings are there for all users of space; the question is whether they will act now to deal with them.”
Originally posted on Live Science.
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