Cyclone Nargis seen by Envisat

Launched in 2002, Envisat was the largest Earth Observation spacecraft ever built. It carried ten sophisticated optical and radar instruments to provide continuous observation and monitoring of Earth's land, atmosphere, oceans and ice caps.

Envisat data collectively provide a wealth of information on the workings of the Earth system, including insights into factors contributing to climate change.

Its largest single instrument was the Advanced Synthetic Aperture Radar (ASAR). Operating at C-band, it ensured continuity of data after ERS-2. The radar featured enhanced capability in terms of coverage, range of incidence angles, polarisation and modes of operation. The improvements allowed radar beam elevation steerage and the selection of different swaths, 100 or 400 km wide.

The Medium Resolution Imaging Spectrometer (MERIS) was a imaging spectrometer that measured the solar radiation reflected by Earth at a ground spatial resolution of 300 m, with 15 spectral bands in visible and near infra-red and programmable in width and position. MERIS allowed global coverage of Earth every three days.

The primary mission of MERIS was the measurement of sea colour in oceans and coastal areas. Knowledge of sea colour can be converted into a measurement of chlorophyll pigment concentration, suspended sediment concentration and aerosol loads over marine areas. It is also used for land and atmospheric monitoring.

In April 2012, contact with Envisat was suddenly lost and the mission came to an end. But ten years of Envisat’s archived data continues to be exploited for studying our planet.