Debris from a defunct Chinese space station could crash to Earth as early as Friday, scientists monitoring it say.
The Tiangong-1 was part of China’s ambitious space programme, and the prototype for a manned station in 2022.
It was put into orbit in 2011 and five years later completed its mission, after which it was expected to fall back to Earth.
Time and place of impact are hard to predict as it is no longer controlled.
The latest estimate for re-entry is between 30 March and 2 April.
Most of the station is likely to burn up in the atmosphere but some debris could survive to hit the surface of the Earth.
Where will it crash?
China confirmed in 2016 that it had lost contact with Tiangong-1 and could no longer control its behaviour, so we don’t really know where it will end up.
The European Space Agency (ESA) said re-entry “will take place anywhere between 43ºN and 43ºS”, which covers a vast stretch north and south of the equator.
Esa has given regular updates on Tiangong-1 and now estimates re-entry between 30 March and 2 April, but says this timeframe is “highly variable”.
The agency expects its forecasts will become more precise closer to the weekend.
How will it crash?
The station is gradually coming close to Earth.
Its rate of descent “will continually get faster as the atmosphere that the station is ploughing through gets thicker,” Dr Elias Aboutanios, deputy director of the Australian Centre for Space Engineering Research, told the BBC.
“The station will eventually start to heat up as it gets close to 100km [from Earth],” he says.
This will lead to most of the station burning up and “it is difficult to know exactly what will survive since the makeup of the station has not been disclosed by China”.
Mr Aboutanios said if it does burn up during night time over a populated area, it “will most certainly be visible, like a meteor or a shooting star”.