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Long March 5B: Chinese rocket crashes uncontrollably


This week another giant Chinese missile stage will hit the earth. Where cannot be precisely predicted. Is Beijing deliberately not addressing the danger?

Enlarge image

Launch of the "Long March 5B" rocket with the core module of the new Chinese space station

Photo: VCG / Getty Images

Until May 2020, the people of Mahounou had little to do with space.

But then on a Monday a pipe about ten meters long crashed from the sky.

The village in Ivory Coast, West Africa, was hit by a piece of debris from a downed Chinese rocket stage.

It came from the maiden flight of Beijing's heavy-duty transporter "Long March 5B".

Weighing 20 tons, the rocket stage tumbled around the earth for days before falling uncontrollably back to the surface.

Much of the space debris burned up from friction in the atmosphere.

But part of it just fell down on Mahounou.

Fortunately, nobody was injured, at least no relevant information is known.

Almost exactly one year later to the day, the world has the same problem: A burned-out stage of the "Long March 5B" will crash uncontrollably onto the earth again in the coming days.

A few days ago it shot the core module of the future »Tianhe« space station into space, but was no longer needed and is now crashing.

And because the rocket is so heavy and partly made of extremely heat-resistant materials, some of it should reach the earth again.

But why does China allow this?

"They deliberately don't care," complains Jonathan McDowell, who works with space debris at the Harvard-Smithsonian Center for Astrophysics, among other things.

He says Beijing made no effort to avoid the junk problem when designing the new missile: "This is real negligence."

Enlarge image

The "Long March 5B" rocket before launch at the Wenchang spaceport

Photo: Guo Wenbin / Xinhua / imago images

"There should be international agreements" that prevented something like this, demands researcher McDowell.

Most countries considered the problem when designing a new missile.

But that is time-consuming: In order to deliberately drop a burnt-out rocket stage, fuel must be saved specifically for the necessary maneuver.

However, this reserve reduces the rocket's maximum payload.

Holger Krag heads the Space Security Department at the European Space Agency (ESA).

"We are tracking the object," he says in an interview with SPIEGEL.

The huge scrap piece is currently on an elliptical orbit between 170 and 310 kilometers in height.

"Every day the level drops a few kilometers further due to the friction with the few air particles that still exist so far out."

The scrap will likely fall into the water - but what if not?

Krag and his team are currently assuming that the rocket will crash to earth between Friday, May 7th and Tuesday, May 11th.

Just where will that be?

That cannot be said seriously, even shortly beforehand.

Only one limitation is possible: the crash will occur somewhere between 41.5 degrees north and 41.5 degrees south latitude.

This results from the orbit on which the missile was launched - and has since then been circling the earth.

That means: In Europe, in the worst case, people in parts of Portugal, Spain, Italy, Greece and other southern European countries have to worry.

And because the surface of the earth consists of a good 70 percent water, it is even very likely that space debris will splash into the ocean somewhere without anyone being nearby.

But nobody can know that exactly.

The crash in May 2020, for example, could have turned out very differently.

For example, US space experts drew attention to the fact that the burnt-out rocket stage could have hit New York City instead of Mahounou if the rocket had fallen from the sky just 30 minutes earlier.

"That could have been extremely dangerous," complained the then NASA boss Jim Bridenstine.

The whole thing is far from being a purely Chinese problem. In the summer of 1979, for example, the 77-tonne US space station "Skylab" crashed uncontrollably over Australia. For decades, the USA, the Soviet Union and Russia, but also Europe, Japan and others have littered space. In low Earth orbit alone, more than 880 burned-out rocket stages were circling at the end of 2019. On higher tracks there are another 250 more. Sooner or later they will all fall to earth. “The other space nations weren't a good role model,” says Hugh Lewis, who studies the problem at the university in Southampton, UK.

The contaminated sites ensure that around 150 tons of space debris burn up every year in the event of uncontrolled reentry.

But the fact that a single part weighs more than 20 tons is something special.

“This is worrying.

It's a really big object, ”says researcher Lewis.

"And it's a systemic problem with this particular launch vehicle."

Compensation paid only once

While more and more other launcher rockets are able to steer their no longer required steps in a targeted manner towards earth and avoid an uncontrolled crash, the problem with the »Long March 5B« occurs for the second time - with two launches so far. And it will probably not be the last time that you have to worry on the ground: The current expansion plan for the Chinese space station provides for the start of the “Wentian” science module for next May - with a “Long March 5B”. It is likely to crash uncontrollably again after its use.

But what is the alternative? Engineers have repeatedly toyed with the idea of ​​converting burnt-out rocket stages into space stations. This was the last suggestion by the head of the US company Nanoracks. His idea is to first attach scientific experiments to the outer shell of the scrap parts. Later, however, it is also conceivable to use robots to convert the tanks so that they can then be used as quarters for astronauts.

But that is a dream of the future at best.

It will be a long time before the old rocket stages are no longer a burden and a potential danger.

So long one can hope that there will be no major damage to the ground - as before.

If so, then it would at least be clear that the starting state, in this case China, would have to pay damages.

This is what it says in the "Convention on Liability under International Law for Damage Caused by Space Objects" negotiated in 1972.

However, the mechanism has only been used once so far.

A crashed Soviet spy satellite had radioactively contaminated a stretch of land in northern Canada in January 1978.

Nothing is known of a lawsuit from Mahounou.

Source: spiegel

All tech articles on 2021-05-06

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