Envisat
Envisat, launched in 2002, was the largest Earth Observation (EO) satellite ever flown. Its multi-instrument capabilities and polar orbit allowed it to provide continuous observation and monitoring of the Earth’s land, atmosphere, oceans and ice caps. Unfortunately, Envisat’s mission ended in 2012 when communication with the satellite was abruptly lost, and efforts to re-establish contact were unsuccessful.
Links to further information:
https://www.esa.int/Applications/Observing_the_Earth/Envisat
https://www.esa.int/Applications/Observing_the_Earth/Envisat/Mission_overview
https://earth.esa.int/eogateway/news/new-envisat-infographic