Science

On Friday, a 23-ton Chinese rocket will fall to Earth. But when and where will he land?

A huge piece of Chinese space debris is expected to crash to Earth on Friday (November 3), but no one knows exactly where or when it will fall.

The debris in question is the 23-tonne (21 metric tons) main stage of the Long March 5V launch vehicle, which reached Earth orbit on Monday (October 31) after the launch of the third and final module of China’s Tiangong space station. .

Since then, atmospheric drag has been pulling the body of the rocket lower and lower. Recent observations and models suggest that Long March 5B will fall on Friday morning, but the error bars for this prediction remain high for now.

Aerospace Corporation, for example, predicts (will open in a new tab) re-entry on Friday at 8:24 am EST (1224 GMT), plus or minus four hours. This large window puts much of North and Central America, nearly all of Africa, and much of Australia into a potential firing line for incoming space debris.

Related: Latest news about China’s space program

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We’ve been through this disturbing exercise before. The Long March 5B main stages have fallen uncontrollably to Earth on all three of the spacecraft’s previous launches, most recently in July, after the rocket sent the Wentian module to Tiangong.

Indeed, this is a (highly undesirable) feature of the Long March 5B. Other orbital rockets are designed so that their first stages are thrown into the ocean or over uninhabited land shortly after launch, or, in the case of SpaceX’s Falcon 9 and Falcon Heavy, drop in one piece for powered landing and reuse in the future. But the Long March 5B main stage reaches orbit and has no way to descend, so it lets atmospheric drag do its job erratically.

While most of the rocket’s body will burn up in the atmosphere when it hits Friday, some of the more durable parts will survive all the way to the ground, putting people and infrastructure at risk on their re-entry path.

“A general rule of thumb is that 20-40% of the mass of a large object reaches the ground, but the exact number depends on the design of the object,” the Aerospace Corporation wrote in a Long March 5B explanatory note. (will open in a new tab). “In this case, we expect 5 to 9 metric tons. [5.5 to 9.9 tons].”

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Most likely, such debris will fall into the ocean, since the seas cover about 70% of the Earth’s surface. But the solid ground took Long March 5B before the wreckage. For example, the remains of a Sang rocket from the first-ever Long March 5B launch in May 2020 appear to have fallen to the ground. (will open in a new tab) in a village in the West African country of Côte d’Ivoire.

To the best of our knowledge, no one was hurt in this incident or any other Long March 5B crash. But the fact that falling rocket bodies pose any risk, albeit a minor one, has drawn condemnation from research advocates and others in the astronaut community.

“Space powers must minimize the risks to people and property on Earth associated with the re-entry of space objects and maximize the transparency of these operations,” NASA Administrator Bill Nelson wrote in a statement. (will open in a new tab) published shortly before the Long March 5B crash in May 2021.

“It is clear that China does not meet responsible standards for its space debris,” he added. “It is very important that China and all space nations and commercial entities act responsibly and transparently in space to ensure the safety, stability, security and long-term sustainability of space activities.”

Mike Wall is the author of Out There (will open in a new tab)(Grand Central Publishing, 2018; illustrations by Carl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall (will open in a new tab). Follow us on Twitter @Spacedotcom (will open in a new tab) or on facebook (will open in a new tab).

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