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- The first European Remote Sensing Satellite ERS-1, launched on 17 July 1991 at 01.46 UTC, operates in a sun-synchronous, near-polar orbit at an altitude of 785 km and an inclination of 98.5 degrees, known as the reference orbit. ERS-1 was conceived as an orbiting platform that would be capable of measuring, on a global scale, the Earth's atmospheric and surface properties with a high degree of accuracy. In fact it uses advanced microwave techniques to collect global measurements and images (much of the data are collected from remote areas such as the southern oceans and the Antarctic) independently of time of day and weather conditions. It also undertakes the measurement of many parameters that are not covered by existing satellite systems, including those of sea state, sea surface winds, ocean circulation and sea/ice levels. Satellite characteristics: -------- Platform: based on the SPOT Multimission Platform Power supply: 4 x 24 Ah batteries; 1.8 kW from solar array Attitude control: 3-axis stabilised earth pointing, with option of 9.5 degrees offset in Roll-Tilt Mode (RTM) Total mass: 2400 kg (at beginning of mission) Overall length: 11.8 m Solar array: 11.7 m x 2.4 m SAR antenna: 10.0 m x 1.0 m Scatterometer antennas: fore/aft 3.6 m x 0.25 m; mid: 2.3 m x 0.35 m Radar Altimeter antenna: 1.2 m diameter Design lifetime: 2-3 years ---------
ERS-1 carries on-board a number of instruments consisting of a core set of active microwave sensors supported by additional, complementary instruments: the Active Microwave Instrument (AMI), which combines a Synthetic Aperture Radar (SAR) operating in image or wave mode and a wind scatterometer, the Radar Altimeter (RA), the Along-Track Scanning Radiometer and Microwave Sounder (ATSR), the Precise Range and Range-rate Equipment (PRARE) and Laser Retroreflectors (LRR). The primary objective of the ERS-1 mission is the monitoring of oceans and sea ice providing essential data for: - improved representation of oceans/atmosphere interactions in climatic models - major advances in the knowledge of ocean circulation and transfer of energy - more reliable estimates of the mass balance of the Arctic and Antarctic ice sheets - better monitoring of pollution and dynamic coastal processes - improved detection and management of land use change The ability of ERS-1 to acquire vast global data sets of ocean, atmosphere, ice and land phenomena contributes to the following fields of study: - Ocean/Ice: ocean circulation, global wind/wave relationships, sea ice and iceberg monitoring, etc. - Physical Earth: accurate determination of the ocean geoid, forestry, glaciology, geology and agriculture studies, etc. - Climate: contribution to the World Climate Research Programme and to the World Ocean Circulation Experiment - Weather and Sea: short and medium-term weather forecasting, sea surface state forecasting, wind speed and direction, location of pelagic fish through the monitoring of temperature fronts Relation between ERS-1 instruments and mission objectives ------------------------------------------------------------ Weather forecasting: AMI wind mode Sea-state forecasting: AMI, wave and wind modes Offshore activity: Altimeter, ATSR, AMI in wave and wind modes Ship routing: Altimeter, ATSR, AMI in wave and wind modes Fisheries (fish location): (Altimeter), (ATSR), AMI in wind mode Sea and iceberg monitoring: Altimeter, ATSR, AMI in image mode Oil and pollution detection: ATSR, AMI in image mode Coastal process: ATSR, AMI in image mode Land applications: (Altimeter), ATSR Ocean circulation: Altimeter(1), ATSR, (AMI in wave mode) Ocean tides: Altimeter(2) Wind fields(3): Altimeter, AMI (in image mode), in wave and wind mode Wave fields(3): Altimeter, AMI (in image mode), in wave and wind mode Polar oceans: Altimeter, ATSR, AMI in all modes. Land ice: Altimeter, AMI (in image mode) Sea-surface temperature: ATSR Marine biology: (ATSR) ------------------------------------------------------------ ( ) indicates limited applicability (1) For large-scale circulation, accurate orbit determination over short arcs is required (2) For solar tides, measurements from other satellites in complementary orbits are required (3) The altimeter and active microwave instrumentation are mutually supportive in deriving the wind and wave fields The complexity of the ERS-1 mission, which effectively consists of a combination of several different missions, requires a very careful approach when planning the mission operations. Taking into account the different mission objectives, and attempting to satisfy them in a quasi-optimal way in the course of ERS-1's lifetime, has held to the definition of phases of activity during the mission: - Phase 0: Orbit acquisition, initial switch-on and functional check-out (2 weeks after the launch) - Phase A: The Commisioning phase, using a 3 day repeat cycle (25 July 1991-10 December 1991) - Phase B : The first ice phase, using a 3 day repeat cycle (28 December 1991-1 April 1992) - Phase R: The Roll-Tilt phase, using a 35 day repeat cycle (2 April 1992-14 April 1992) - Phase C: The first multi-disciplinary phase, using a 35 day repeat cycle (14 April 1992-23 December 1993) - Phase D: The second ice phase, using a 3 day repeat cycle (23 December 1993-10 April 1994) - Phase E: The first geodetic phase, using a 172 day repeat cycle (10 April 1994-28 September 1994) - Phase F: The second Geodetic Phase, using a 172 day repeat cycle (28 September 1994-21 March 1995) - Phase G: The second Multi-Disciplinary Phase, using a 35 day repeat cycle (21 March 1995-10 March 2000) In the first half of April 1992, the satellite was operated in a Roll-tilt-mode (RTM) to allow SAR imaging at a different view angle. In fact by rotating the satellite body around its velocity vector (so-called 'Roll-tilt mode') the angle at which all the instruments look at the Earth can be varied. This allows experimentation with the SAR at an incidence angle of 35 degrees instead of the standard 23 degrees, thereby permitting analysis of a totally different set of signatures from objects on the Earth's surface, including in particular vegetation. Related URL: The ERS Missions: http://earth.esa.int/ers ERS-1 Design: http://earth.esa.int/ers/satconc For any query, please refer to: ESA/ESRIN Earth Observation Help Desk http://earth.esa.int Group: Platform_Details Entry_ID: ERS-1 Group: Platform_Identification Platform_Category: Earth Observation Satellites Platform_Series_or_Entity: ERS Earth Resource Satellite Short_Name: ERS-1 Long_Name: European Remote Sensing Satellite-1 End_Group Group: Synonymous_Platform_Names Short_Name: ERS-1 End_Group Group: Platform_Associated_Instruments Short_Name: ATSR Short_Name: RA Short_Name: SAR Short_Name: AMI End_Group Group: Orbit Orbit_Altitude: 782 to 785 km Orbit_Inclination: 98.52 deg Period: 100 min Repeat_Cycle: 3-day, 35-day and 176-day Orbit_Type: LEO > Low Earth Orbit > Polar Sun-Synchronous End_Group Creation_Date: 2007-09-14 Online_Resource: http://earth.esa.int/ers/satconc/ Online_Resource: http://earth.esa.int/ers/ Online_Resource: http://www.astronautix.com/craft/ers12.htm Sample_Image: http://earth.esa.int/icons/eeo/_ers-1_fully_deployed.gif Group: Platform_Logistics Launch_Date: 1991-07-17 Launch_Site: Kourou, French Guiana Design_Life: 2-3 YRS Primary_Sponsor: ESA End_Group End_Group
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