Research activities in response to the Envisat Announcement of Opportunity

Since the launch of ERS-1 in 1991, ESA has issued several Announcements of Opportunity (AOs) for scientific research and application development using ERS satellite data. A total of more than 1000 projects proposed by scienti fic investigators from around the world have been selected and accepted. Th e outcomes of the various AO projects have been presented at ESA-organised Symposia and Workshops and published in the scientific literature. The Envi sat AO, issued in December 1997, led to the selection of 674 proposals in s upport of scientific research, application development and calibration and validation. This is the largest and most diverse AO ever issued by ESA in t he Earth-observation field.