Inactive artificial objects in orbit, most of which, too small to be tracked, remain invisible yet lethal to satellites.
Orbital debris are the inactive artificial fragments in orbit, rocket stages, decommissioned satellites and collision shards, that threaten active craft. According to the European Space Agency, there are around fifty-four thousand objects larger than ten centimetres, but also more than one hundred and forty million fragments smaller than a centimetre, undetectable by current surveillance systems. These invisible fragments are perfectly lethal, for they travel at a relative speed of around twenty-eight thousand kilometres per hour. This partial invisibility vitiates the modelling of space risk at its root, the insurer having to estimate a collision probability from a population it does not count but assumes, which turns pricing into conjecture rather than measurement.
A shard of a few centimetres, too small to be tracked by radars, can destroy a satellite on impact, even though the insurer could not incorporate it into its collision model.
débris spatiaux, space debris