European Remote Sensing Satellite ERS-1

The European Remote Sensing Satellite ERS-1, a spaceborne radar developed by the European Space Agency (ESA) from 1979 to 1990, was the first purely civilian Earth observation satellite. Launched on June 17, 1991, into a Sun-synchronous orbit at 782–785 km altitude with a 98.5° inclination and 100-minute orbital period, it operated until its mission ended on March 10, 2000. Its primary instrument was a C-band (5.3 GHz) Synthetic Aperture Radar (SAR) with linear vertical polarization, a pulse repetition frequency (PRF) of 1640-1720 Hz, a pulsewidth of 37.12 µs, and a peak power of 4.8 kW. This SAR, developed under DASA, used linear frequency modulation with a 15.55 MHz bandwidth, achieving across-track and along-track resolutions of ≤ 26.3 m and ≤ 30 m respectively, and covering a 102.5 km swath. ERS-1 also carried a Ku-band (13.8 GHz) radar altimeter with a 1.2 m parabolic antenna, a PRF of 1020 Hz, a pulsewidth of 20 µs, and a peak power of 55 W, capable of measuring height with an accuracy of up to 5 cm and offering a range resolution of 10 cm. Its successor, ERS-2, launched on April 21, 1995, operated in tandem with ERS-1 from August 1995 to June 1996, enabling advanced interferometric analysis for detecting ground changes with centimeter-level accuracy before ERS-2 was deorbited starting July 5, 2011.

radartutorial.eu: https://www.radartutorial.eu/19.kartei/09.space/karte001.en.html