Envisat

The Environmental Satellite (Envisat)-1, launched in 2002, was developed by EADS Astrium for the European Space Agency (ESA) as the successor to the ERS-1 and ERS-2 remote sensing satellites. As Europe's largest Earth observation satellite at 8.2 tonnes, Envisat carried the Advanced Synthetic Aperture Radar (ASAR) instrument, which extended the mission of the Active Microwave Instrument (AMI) SAR instruments from previous ERS satellites. Operating at 5.331 GHz (C-band) with a dual linear polarization, ASAR transmitted alternating vertically and horizontally polarized electromagnetic waves, receiving backscatter simultaneously on two separate channels to derive the complete scattering matrix of a scene on a pixel-by-pixel basis. The ASAR instrument utilized an active phased array antenna, with incidence angles ranging from 15° to 45° and a swath width of 500 to 800 km, from an orbit of 796 km with a 98.54° inclination and a 100-minute orbital period.

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