Envisat was successfully launched on 1 March 2002!

The ESA's ENVISAT satellite, expected to be launched in November 2001, carries the Advanced SAR (ASAR) instrument. The ASAR, operated at C-band (5.331 GHz), can be regarded as an advanced version of the SAR instruments on board the ERS1 and ERS2 satellites. Its beam elevation steerage allow the selection of different swaths at different incidence angles, providing a swath coverage of over 400-km wide using ScanSAR techniques. In alternating polarisation mode, transmit and receive polarisation can be selected allowing scenes to be imaged simultaneously in two polarisations.

In the image mode, ASAR operates in one of seven predetermined swaths (100 km swath width) with either vertically or horizontally polarised radiation; the same polarisation is used for transmit and receive (i.e., HH or VV). The ground resolution is about 30 m (three looks), sampled at pixel separation of 12.5 m.

In the alternating polarisation mode (in one of seven possible swaths), two images in two polarization modes (HH & VV, or HH & HV, or VV & VH) are acquired. The ground resolution is about 30 m (1.8 equivalent number of looks), sampled at 12.5 m spacing.

When operating in the ScanSAR mode, a wide swath of > 400 km can be achieved, at a ground resolution of about 150 m (11.5 equivalent number of looks), sampled at 75 m pixel spacing.

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