Debris from Chinese missiles threatens to fall back to Earth uncontrollably

Debris from parts of China’s Long March 5B rocket will crash into Earth this weekend – but space agencies don’t know when and where.

The debris is expected to return to Earth’s atmosphere sometime on May 8 or 9. The Pentagon expects to land around 11 p.m. GMT on Saturday, but has a nine-hour margin of error on both sides.

Space agencies around the world are anxiously following the rocket’s uncontrolled descent. The White House said on Wednesday that NASA was doing everything it could to locate the remains of the missile.

The Long March 5B took off last April to install the first part of a Chinese space station under construction. The parts of this rocket that are now falling to Earth orbit the planet at more than 27,000 kilometers per hour.

It is one of the largest forms of space debris to return to Earth – about 30 meters long and weighing more than 20 tons. The debris path could land as far north as New York, Madrid or Beijing and as far south as New Zealand’s capital Wellington, Harvard-based astrophysicist Jonathan McDowell told Reuters this week.

Debris from another Long March missile landed on some buildings in Ivory Coast in 2020, causing damage but no injuries or deaths.

US Secretary of Defense Lloyd Austin said on Thursday that the US military had no plans to bring down the approaching debris. “We have the ability to do a lot of things, but we have no plan to shoot it,” he told reporters.

Hopefully, he said, the missile will land “where it won’t hurt anyone [… in] the ocean, or something ”.

China has said the risks are minimal, as most missile components are likely to be destroyed on return. The chance to do damage […] on the ground is extremely low, ”Chinese Foreign Ministry spokesman Wang Wenbin told reporters on Friday.

Many experts agree that most of the debris is likely to be destroyed by the friction as it enters the Earth’s atmosphere at high speed.

“The most likely event will be that all the debris that survives the intense heat of the re-entry will end up in the oceans or uninhabited areas,” wrote specialist publication Space News. Nevertheless, “the risk of damage to persons or property remains”.

‘Negligent on the part of China’

Given the sheer size of the rocket fragments, some experts say there is a significant risk of a significant piece falling to Earth instead of burning up in the atmosphere. “A rough rule of thumb” suggests that “between 20% and 40% of dry mass can survive,” Holger Krag, head of the European Space Agency’s space debris division, told The Guardian.

This would be enough to cause major damage if it landed on an inhabited area. Currently, the most likely place to land is in a long stretch around the equator – which includes the east coast of Africa to the west coast of South America, the Pacific and Indian oceans, and part of Northern Australia – according to Aerospace Corp, an in California-based NGO that advises the US government on space matters.

It is difficult to calculate exactly where the land will land, because the speed at which it moves means that the slightest error in calculating the point of entry into the atmosphere can lead to a difference of tens of thousands of kilometers.

>> You can follow the trajectory of the rubble here.

All this could have been avoided by redesigning the missile. In the 1970s, American and Soviet rockets of comparable size to this first stage of the Long March 5B crashed to Earth – but now technology has advanced to the point where space agencies can design the central part of their rocket. a way that it won’t orbit the Earth.

Abandoned spacecraft are usually drifted far from Earth’s atmosphere or orbiting other masses such as the moon. Remote controls on rocket engines allow people on Earth to control their descent so that they land in the ocean, far from populated areas. Operations like this often land it in the vast seas of the South Pacific, between New Zealand and South America.

‘What’s bad is that it is really negligent on the part of China. We don’t let things over ten tons fall out of thin air on purpose, ”astrophysicist McDowell told The Guardian.

This problem is likely to worsen as a growing number of non-state actors become involved in space exploration; more and more countries and private companies are sending satellites and rockets, leaving space debris in their wake. There is currently more than 9,000 tons of space debris orbiting the Earth – with no accurate maps of where it’s going.

This article has been translated into French from the original.

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