LeoLabs, in Silicon Valley, which has been monitoring the paths of a defunct Russian satellite and a discarded Chinese rocket segment, using radars to track objects in orbit, has estimated that they may come within 25 metres of each other. It sees them converging over Antarctica at 00:56 GMT (01:56 BST) on Friday.

With a combined mass at over 2.5 tonnes and relative velocity of 14.66km/s (32,800mph), any collision would be catastrophic and produce a shower of debris. Given the altitude of almost 1,000km, the resulting fragments would stay around for an extremely long time, posing a threat to operational satellites.

Neither Kosmos-2004, which was launched in 1989, nor the ChangZheng rocket stage, launched in 2009, can be moved. So, there is no possibility to influence the event.

Some experts who've looked at the available data think Kosmos-2004 and the ChangZheng rocket stage will pass with a far greater separation. Dr Moriba Jah, an astrodynamicist at the University of Texas at Austin, has worked out the miss distance to be about 70 metres. And the Aerospace Corporation, a highly respected consultancy, comes to a similar conclusion.

LeoLabs said there were no signs of debris over Antarctica on Friday morning.

Not content with littering own planet - we have to litter the sky as well!

As of January 2019, more than 128 million pieces of debris smaller than 1 cm (0.4 in), about 900,000 pieces of debris 1–10 cm, and around 34,000 of pieces larger than 10 cm were estimated to be in orbit around the Earth.

The video of orbiting space junk is terribly misleading. Each dot is way, way larger than they are in reality. The scale is out of all proportion. It makes it seem that any space craft orbiting the earth is bound to hit or be hit by some of that junk.

In reality, the manned 'Skylab', which goes whizzing around the earth at 18,000 mph, has not encountered any of that junk. Nor can any astronauts on 'Skylab' see any of that junk.

The video of orbiting space junk is terribly misleading. Each dot is way, way larger than they are in reality. The scale is out of all proportion. It makes it seem that any space craft orbiting the earth is bound to hit or be hit by some of that junk.

In reality, the manned 'Skylab', which goes whizzing around the earth at 18,000 mph, has not encountered any of that junk. Nor can any astronauts on 'Skylab' see any of that junk.

Erm ..... it's an animation .....

..... and Skylab died some time ago:

Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. Skylab's orbit gradually decayed and it disintegrated in the atmosphere on July 11, 1979, scattering debris across the Indian Ocean and Western Australia.