Chinese rocket falls back to Earth: What do we know so far?

An out-of-control rocket is plunging towards the Earth – and it is not clear where it is going.

The core of the Chinese Long March 5B rocket carried the “core module” of the country’s space station into low Earth orbit last week.

But after that mission was complete, the rocket appears to have fallen into an orbit that could see it plunge towards the Earth.

It is not clear how the 30-metre-tall rocket will fall, and where exactly it will land.

Why is this happening?

The rocket was sent up to carry the central core of China’s new space station up to orbit. The Tianhe space station module appears to be orbiting as planned – but the core stage is now falling back to Earth.

As such, it is now falling to Earth on an unpredictable and potentially dangerous trajectory. It is being tracked as it does, watched as its orbit brings it closer to the Earth ahead of it burning up and pieces possibly hitting the ground.

Knowing why this has happened – and what might happen now – is complicated somewhat by the fact that the Chinese space agency tend to give limited information about their work. That makes it difficult to know what went wrong, why the rocket is falling, whether it will survive the re-entry and more.

When and where might it fall?

It is very difficult to know. The rocket is still so high up, and travelling in such an unpredictable motion, that it is difficult to say how the rest of its journey back down to Earth might go.

But it is likely to crash down on Sunday, 9 May, according to the European Space Agency, though it said there was a margin of error of more than a day.

Where that might happen is harder to know, in part because relatively little is known about the part of the atmosphere it is travelling through and how that affects spacecraft. It is also moving so fast that even a small change in its movement could lead to a big variation in its path.

It will probably happen somewhere in the ocean – simply because that makes up some three-quarters of the surface of the Earth. Much of the land area is uninhabited, too, meaning that the chance it will cuase much damage is very low.

As its arrival approaches, the estimate of both the location and the time should be able to be refined, making that window much smaller.

Has this happened before?

Yes – and it could have been much worse. Last year, parts of one of the same rockets fell down to Earth, in a situation with marked similarities to this one.

Most of the pieces landed in the Atlantic Ocean. But pieces of debris were reported in Ivory Coast, and experts calculated that it had missed New York by minutes.

But in another way it is truly unprecedented. Since 1990, nothing weighing more 10 tonnes have fallen back to Earth uncontrolled – and the Chinese rocket is thought to weigh about 10 tonnes.