ERS-1 was launched in July 1991 with its primary instruments being an Active Microwave Instrument (AMI), a Radar Altimeter (RA-1), an Along-Track Scanning Radiometer and microwave sounder (ATSR-1). The AMI instrument was comprised of two separate radars - a Synthetic Aperture Radar (SAR) and a Wind Scatterometer. These systems enabled three modes of operation - Image Mode, Wave Mode (both performed by the SAR) and Wind Mode (performed by the Wind Scatterometer).
The ERS-1 mission ended in March 2000. Full details of the ERS-1 mission can be found here.
ERS-1 (solar panel to the left of the platform, SAR and Wind Scatterometer to the right of the platform.) Learn more about the ERS-1 spacecraft and sensors here.
The ERS-1 acquisition plan and the various modes of operation are provided here. The standard operational mode provided a 35 day repeat orbit. During the early part of the ERS-1 mission other repeat periods were used: an ice mode (3 day repeat),
An example plan for February 1996 is shown below: