Don Kessler

Don Kessler


20/04/2017 3:29 pm


ESA/J. Mai


Retired astrophysicist and former NASA scientist Donald Kessler seen attending the European Conference on Space Debris at ESA in Darmstadt, Germany, on 18 April 2017.

Since 1957, more than 5250 space launches have led to an orbiting population today of more than 23 000 tracked debris objects.

Only about 1200 are working satellites. The remaining are classified as space debris and no longer serve any useful purpose. A large percentage of the routinely tracked objects are fragments from the approximately 290 breakups, explosions and collisions of satellites or rocket bodies that are known to have occurred.

An estimated 750 000 objects larger than 1 cm and a staggering 166 million pieces larger than 1 mm are thought to reside in commercially and scientifically valuable Earth orbits.

Relative orbital speeds of up 56 000 km/h mean that even centimetre-sized debris can seriously damage or disable a working satellite, and collisions with objects larger than 10 cm will lead to catastrophic break-ups, releasing clouds of hazardous debris fragments that will go on to cause further catastrophic collisions, potentially leading to an unstable debris environment in some orbital regions.

This run-away scenario is known as the “Kessler syndrome” because it was first postulated by Don in 1978.

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