Is the worldwide frequency of natural disasters actually going up, or are increasingly crowded and interconnected human societies becoming more susceptible to them? Major catastrophes are currently occurring once a fortnight on average.

In recent years Earth Observation satellites have become a new asset at the disposal of emergency response teams. Satellites can perform rapid damage-mapping to help guide rescue efforts.

Such help was given on an informal basis for many years, but formalised in 2000 when ESA, CNES and CSA formed the ‘International Charter - Space and Major Disasters’ – an agreement to prioritise image acquisition over disaster zones. A decade on the Charter has 11 member space agencies worldwide. As well as Charter activations supporting short-term disaster response, satellites have broader applications for disaster recovery. Different sensors have different strengths: optical images for damage-mapping – medium-resolution for a snapshot of overall effects, with higher-resolution acquisitions depicting damage to road networks or even individual buildings – while imaging radar has particular sensitivity to floods and waterlogged ground and imaging spectrometers or radiometers can show forest fire plumes, burnt scars or currently burning ‘hotspots’.