In the 1990s, the European Space Agency ESA launched two ERS (Earth Remote Sensing) satellites.

In July 1991 ESA’s first earth observation mission was launched into space with ERS-1. Its payload consisted of five instruments: AMI (Active Microwave Instrument), which provided the functions of an imaging synthetic aperture radar (SAR) and a wind scatterometer; RA (Radar Altimeter); MWR (Microwave Radiometer); ATSR (Along Track Scanning Radiometer); and PRARE (Precise Range and Range-rate Equipment). The ERS-1 mission ended on March 10, 2000 after more than 45,000 orbits.

Tabelle: ERS-1 Mission Parameters
Dimensions 12 m × 12 m × 2.5 m
Total mass 2.16 t
Payload 888 kg
Number of instruments 5
Launcher Ariane 4
Launch July 1991
End of mission March 10, 2000

Table: ERS-1 Orbit Parameters
Semi-major axis 7159 km
Orbit altitude (mean) 782 km
Inclination angle 98.5°
Orbital period 100 min
Orbit polar, sun-synchronous
Overflight time absteigender Knoten 10:30 Uhr vormittag
Orbits per day 14.3
Revisit 35 days (optionally 3 days or 168 days with slightly different orbit parameters)

The successor to ERS-1, the earth observation mission ERS-2 (Earth Remote Sensing Satellite 2), was launched in April 1995. For several years, both ERS satellites simultaneous monitored our home planet. ERS-2 has the same instrument suite as ERS-1 on board, with the addition of GOME (Global Ozone Monitoring Experiment) a sensor developed to study earth’s atmosphere. After 15 years in orbit, ERS-2 is still supplying valuable data, and this long-term availability makes it possible to generate lengthy time series, an important resource for climate studies.

Tabelle: ERS-2 Missionsparameter
Dimensions 11.8 m × 11.7 m × 2.4 m
Total mass 2.52 t
Payload 1.0 t
number of instruments 6
Launcher Ariane 4
Launch April 21, 1995

Tabelle: ERS-2 Orbit Parameters
Semi-major axis 7147 km
Orbit altitude (mean) 785 km
Inclination angle 98.5°
Orbital period 100 min
Orbit polar, sun-synchronous
Overflight time descending node, 10:30 am
Orbits per day 14.3
Revisit 35 days

….. More on ERS at the ESA Website

Birgit Schättler
German Aerospace Center (DLR)

Remote Sensing Technology Institute
, SAR Signal Processing
Tel: +49 8153 28-1352

Fax: +49 8153 28-1420

Dr.-Ing. Joachim Schwarz
German Aerospace Center (DLR)

German Remote Sensing Data Center
, National Ground Segment
Tel: +49 3981 480-133

Fax: +49 3981 480-299

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The end of an era - ERS-2 retires after 16 years (