ERS 1

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General

Designation	21574 / 91050A
Launch date	17 Jul 1991
Country of origin	Europe
Mission	Remote sensing
Perigee/Apogee	768/769 km
Inclination	98.5°
Period	100.2 min
Orbital cycle	3, 35 and 176 days
Launch vehicle	Ariane V44

ESA's first remote sensing satellite. Cost: $500 million

Since early 1994 the satellite transmits with the backup travelling wave tube because the primary one failed.

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End of life

Out of service	10 Mar 2000
Cause	failure of the attitude control system

sat-index articles

Technical data

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Specifications

Prime contractor	Dornier
Platform	MMS Spot Mk 1
Mass at launch	2400 kg
Payload mass	1100 kg
Dry mass	2080 kg
Length	11.8 m
Solar array	11.7 x 2.4 m
SAR antenna	10 x 1 m
Radar altimeter	1.2 m (diameter)
Stabilization	3-axis
DC power	2500 W
Design lifetime	3 years

Downlink: 2225 MHz

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AMI (Active Microwave Instrument)

Frequency	5.3 GHz (C-band)
SAR resolution	26 m
SAR swath width	99 km
Scatterometer resolution	47 km
Scatterometer swath width	613 km (fore and aft) 809 km (mid)

Mission: payload all-weather high-resolution images of land and ocean, windspeed and direction, ice mapping, pollution monitoring.

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RA (Radar Altimeter)

Frequency	13.8 GHz (Ku-band)
Accuracy (wave height)	+/- 0.5 m
Altitude accuracy	0.1 m

Mission: windspeed and sea surface elevation, ice sheet topography.

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ATSR (Along-Track Scanning Radiometer)

Wavelengths	1.6, 3.7, 10.8 and 12.0 µm
Accuracy (sea surface temperature)	+/- 0.5 K

Mission: images of sea surface temperature, total water vapour content of atmosphere, cloud, aerosols, haze, land and ice surface emissivity.

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Microwave Sounder

Frequency	23.8 and 36.5 GHz
Altitude accuracy	0.02 m
Telemetry/data	S-band

Also equipped with Laser Reflectometer (LR), Precise Range and Range-rate Equipment (PRARE) and Instrument Data Handling and Transmission (IDHT).

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