Cosmic Kerplunk

It seems we’ve all been walking about oblivious to the risks of collisions over our heads. In a sort of orbital pinball, thousands of satellites have been zooming round the earth missing each other for years – until now, that is.

The collision of a Russian satellite with a privately owned American one was the mass equivalent of a Ford Fiesta skidding into an MG Midget – a spectacle easily imagined by anyone who has visited a supermarket car park during the recent freeze – and has littered Earth's 500-mile orbit with debris. Some of this may eventually burn up as spectacular meteors but most of it will rather inconveniently hang around up there for years to come, ready to collide with other satellites.

With 17,000 known pieces of debris already whizzing about in orbit, collisions, already the single biggest danger to space flight, will be increasingly common in years to come. Add to this the inevitable decay of earlier satellites and it may eventually become too risky to send manned craft into space at all, leaving us ironically marooned inside a cage of our own creation.

Anyone familiar with the works of the late, great John Wyndham could be forgiven for feeling a little uneasy about all of this; in ‘The Day of the Triffids’ , the survivors eventually concude that it must have been the release of optical and biological weapons from accidentally damaged satellites which ultimately paved the way for the destruction of human civilization as we know it.