Why Chinese rocket's crash should alert us to the problem of space junk

Navigating the celestial traffic jam caused by defunct rockets, satellites and their debris is both challenging and dangerous

The crash of a 22-tonne, 33-metre Chinese rocket last weekend highlighted, once again, the problem of space junk. The Long March 5B Rocket splashed down safely into the sea near the Maldives. But this sort of incident will keep happening and each one poses some risks.
 
There are literally millions of bits and pieces of defunct satellites and rockets floating in orbit around the Earth. Space agencies and specialised outfits like the US Space Surveillance Network keep track of around 500,000 such objects with an aggregate weight of over 8,500 tonne.
 
“Floating”, in fact, is the wrong word.