Another Chinese missile will crash to Earth on Saturday. What is the danger?

The main stage of China’s Long March 5B missile is set to return to Earth uncontrollably next week, in a re-entry that China is closely tracking and says poses little risk.

The 25-ton (23 metric tons) rocket stage, which was launched on July 24, is expected to re-enter the Wentian lab’s cabin module to the unfinished Tiangong Space Station in China. Earth On July 30 at 7:24 p.m. ET, take 16 hours or more, according to researchers at The Aerospace Corporation’s Center for the Study of Orbital and Return Debris (Opens in a new tab).

Exactly where it will land is unknown, but the potential debris field includes the United States, India, Australia, Africa, Brazil and Southeast Asia, According to the Aerospace Corporation (Opens in a new tab)It is a non-profit research center funded by the US government and headquartered in California.

The first stage of a rocket, its booster, is usually the largest and most powerful section. Typically, trajectories of rocket boosters are planned to avoid orbit and land harmlessly into the ocean, or, if successful in orbit, perform a controlled reentry with a few bursts of their engines. But the Long March 5B booster engines cannot be restarted once they are stopped, causing the booster to spin around the Earth before landing in an unpredictable location.

This is the third time in two years that China has disposed of its missiles in an uncontrollable manner. In the second case, in May 2021, the wreckage of the missile fell unharmed into the Indian Ocean. But the first incident, in May 2020, caused metal objects to fall on villages in Ivory Coast, although no injuries were reported.

Due to their massive size, Long March 5B’s boosters can be particularly vulnerable during uncontrolled re-entry, meaning that significant portions of their mass do not burn safely in the atmosphere.

“The general rule is that 20% to 40% of the mass of a large object will reach Earth, but the exact number depends on the design of the object,” Marlon Sorge, space debris expert at the Aerospace Corporation, said. He said in an online Q&A (Opens in a new tab). “In this case, we expect about five to nine metric tons [6 to 10 tons].

“In general, for the upper stage, we see the small and medium tanks more or less intact, and the large engine components,” added Sorge. “Large cabinets and leather will probably break down at this key stage. We’ll also see lightweight items like insulation flaking off. The melting point of the materials used will make a difference in what’s left.”

What is the danger?

According to The Aerospace Corporation, since more than 88% of the world’s population falls under a rocket’s orbital footprint, some of the remaining debris could fall into a populated area. But Mullhaupt said the odds of this wreck infecting a person range from 1 in 1,000 to 1 in 230 and the risks to one individual are much lower — about 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 greater. The internationally accepted injury risk threshold for uncontrolled re-entry of missiles is 1 in 10,000, according to a 2019 report from the US government’s Standard Practices for Orbital Debris Mitigation.

Despite the relatively low risk of harm to people or property, China’s decision to launch missiles without options for controlled re-entry has drawn some stern warnings from US space experts.

“Space-faring nations must minimize the risks to people and property on Earth from re-entry of space objects and maximize transparency regarding these operations,” NASA Administrator Bill Nelson wrote in a statement (Opens in a new tab) After landing the 2021 Long March 5B. “It is clear that China is failing to meet responsible standards regarding space debris.”

“Why are we worried? Well, he caused property damage last time [in 2020]People will have to prepare as a result, Ted Mullhaupt, aerospace expert and consultant with Aerospace Corporation, said during a press conference. “It is not necessary. We have the technology so that we do not have this problem.”

China dismissed these concerns as “shameful propaganda”. In 2021, Hua Chunying, then a spokeswoman for China’s Foreign Ministry, accused Western reports of bias and “textbook-style double standards” in their coverage of China’s falling missiles. For example, in March 2021, the debris of a SpaceX rocket crashed into a farm in Washington state, an event that Western news outlets claim has been covered favorably and using “romantic words.”

According to Article VII of the 1967 Outer Space Treaty, to which all major space-faring nations — including China — are parties, any country that sends an object into space is internationally liable for damage it may cause to another party upon its return. to ground. If this happens, the incident will be handled in a claims commission or dealt with through diplomatic channels – as happened in 1978, when the crippled Soviet satellite Kosmos 954 crashed in western Canada, spraying a nearly 370-mile (600-kilometre) path With debris from a broken nuclear reactor on board.

All major launch nations will have parts of space objects returning to Earth in an uncontrolled way, said Christopher Newman, professor of space law and policy at Northumbria University in London, but that creating an international consensus on how to deal with them is difficult given current geopolitical tensions.

“This is a problem that needs an international solution, especially since objects like rocket ones are three times more likely to affect cities in the ‘Global South’,” Newman told Live Science. “However, we just have to look at countries’ attitude towards space tracking and awareness of conditions Space, as well as the problem of debris in Earth’s orbit, to see that the international community does not yet have the motivation to try to solve this problem.

“As a lawyer, it is clear to me that the momentum for change only comes when there is some form of disaster or tragedies – and then it is often too late,” he said. “Warnings are in place for all users of space, and the question is whether they will take action now to deal with them.”

Originally published on Live Science.