# ERS-1

> European Earth observation satellite (1991-2000)

**Wikidata**: [Q987402](https://www.wikidata.org/wiki/Q987402)  
**Source**: https://4ort.xyz/entity/ers-1

## Summary
ERS-1 is a European Earth observation satellite launched on 17 July 1991 to perform radar and other remote-sensing observations from a sun-synchronous orbit. It was the first satellite in the European Remote-Sensing Satellite series, operated by ESA centres and followed in the series by ERS-2.

## Key Facts
- ERS-1 is an Earth observation satellite and a synthetic aperture radar (SAR) satellite.  
- Launch date and time: 1991-07-17 at 01:46:31 (COSPAR ID 1991-050A; NSSDC ID 1991-050A).  
- Satellite catalog number (SCN): 21574.  
- Launch vehicle: Ariane 40 (flight V-44); launch site/start point: ELA-2.  
- Launch mass (launch weight): 2,384 kilogram.  
- Spacecraft bus: SPOT; primary contractor/manufacturer: DASA (general contractor); Matra Marconi Space (applies to spacecraft bus).  
- Orbit: sun-synchronous; periapsis 741 km; apoapsis 786 km; orbital inclination 98.7704°; eccentricity 0.0031449; orbital period ~100 minutes.  
- Power: spacecraft solar array configuration listed as 2 arrays with a recorded value of 2600 (value and unit recorded in source).  
- Design life and service life: design life 3 years; documented service life 9 years.  
- Followed by: ERS-2.  

## FAQs
### Q: What was ERS-1's mission?
A: ERS-1 was a European Earth observation satellite equipped for synthetic aperture radar imaging and other remote sensing to monitor Earth's surface and oceans from a sun-synchronous orbit.

### Q: When and how was ERS-1 launched?
A: ERS-1 was launched on 1991-07-17 at 01:46:31 from ELA-2 on an Ariane 40 (V-44) rocket.

### Q: How long did ERS-1 operate?
A: ERS-1 had a design life of 3 years but a recorded service life of 9 years; it experienced an attitude-control failure documented on 2000-03-10.

### Q: Who operated and manufactured ERS-1?
A: ERS-1 was operated by the European Space Operations Centre and the ESA Centre for Earth Observation. DASA served as the general contractor and Matra Marconi Space was involved for the spacecraft bus.

### Q: What orbit did ERS-1 use for observations?
A: ERS-1 operated in a sun-synchronous orbit with approximate altitude range 741–786 km, inclination 98.7704°, eccentricity 0.0031449, and an orbital period of about 100 minutes.

## Why It Matters
ERS-1 was the first satellite in the European Remote-Sensing Satellite series and established a European capability for systematic radar and optical monitoring of Earth from a sun-synchronous orbit. Its synthetic aperture radar payload enabled day-and-night, all-weather imaging of land and ocean surfaces, supporting applications such as oceanography, sea-ice monitoring, land-surface studies, and disaster monitoring. By delivering routine, high-revisit remote-sensing data, ERS-1 contributed to the development of operational Earth observation services in Europe and provided continuity for research and environmental monitoring that informed scientific studies and practical applications. The satellite’s extended operational life beyond its 3-year design demonstrates technical robustness and provided nearly a decade of data prior to the attitude-control failure in 2000, laying groundwork for follow-on missions such as ERS-2.

## Notable For
- Being the first craft in the European Remote-Sensing Satellite (ERS) series.  
- Carrying synthetic aperture radar capability for day/night, all-weather surface imaging from a sun-synchronous orbit.  
- Operating substantially longer than its 3-year design life (documented service life of 9 years).  
- Launch mass of 2,384 kg and use of the SPOT spacecraft bus for an Earth-observation SAR platform.  
- Providing routine Earth-observation data that enabled operational and scientific monitoring of oceans, sea ice, and land surfaces.

## Body

### Overview
- Name and aliases: ERS-1; also written European Remote-Sensing Satellite-1 and ERS 1.  
- Instance of: Earth observation satellite and synthetic aperture radar satellite.  
- Part of: European Remote-Sensing Satellite programme.  
- Parent astronomical body: Earth.

### Launch and deployment
- Launch date/time: 1991-07-17 at 01:46:31.  
- Launch vehicle: Ariane 40 (flight V-44).  
- Launch site / start point: ELA-2.  
- Space tug/stage information recorded as: H10 (qualifier L416a).  
- COSPAR ID: 1991-050A.  
- NSSDC ID: 1991-050A.  
- Satellite catalog number: 21574.

### Orbit and flight parameters
- Orbit type: Sun-synchronous orbit.  
- Periapsis (perigee): 741 km.  
- Apoapsis (apogee): 786 km.  
- Orbital inclination: 98.7704°.  
- Orbital eccentricity: 0.0031449.  
- Orbital period: ~100 minutes.

### Spacecraft and technical specifications
- Launch mass (launch weight): 2,384 kg.  
- Spacecraft bus: SPOT.  
- Manufacturer / contractors: DASA (general contractor); Matra Marconi Space (applies to spacecraft bus).  
- Power: spacecraft solar array configuration recorded as two arrays with value 2600 (unit recorded in source).  
- Instance classifications: Earth observation satellite and synthetic aperture radar satellite.

### Mission timeline and operations
- Project commissioning period: 1991-07-25 to 1991-12-10.  
- Service entry: 1991-12-28.  
- Documented failure: attitude-control failure on 2000-03-10.  
- Design life: 3 years.  
- Documented service life: 9 years.  
- Followed by the ERS-2 mission in the ERS series.

### Operators and identifiers
- Operators: European Space Operations Centre; ESA Centre for Earth Observation.  
- Image/media: https://commons.wikimedia.org/wiki/Special:FilePath/ERS-1_ESA382541_(cropped).jpg  
- Commons category: ERS-1.  
- Other identifiers: google_knowledge_graph_id: /g/11x1nr9ql; wolfram_language_entity_code: Entity["Satellite","21574"].

## Schema Markup
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "ERS-1",
  "description": "ERS-1 is a European Earth observation satellite (synthetic aperture radar) launched on 1991-07-17 and operated in a sun-synchronous orbit to perform remote sensing.",
  "url": "https://earth.esa.int/eogateway/missions/ers/description",
  "sameAs": [
    "https://earth.esa.int/eogateway/missions/ers/description",
    "https://commons.wikimedia.org/wiki/File:ERS-1_ESA382541_(cropped).jpg"
  ],
  "additionalType": "Earth observation satellite"
}

## References

1. [Source](https://space.skyrocket.de/doc_sdat/ers-1.htm)
2. [Source](https://earth.esa.int/eogateway/missions/ers/description)
3. Jonathan's Space Report
4. [Source](https://space.skyrocket.de/doc_sat/astrium_spot.htm)
5. [Source](https://earth.esa.int/eogateway/missions/ers)
6. [Source](https://heavens-above.com/orbit.aspx?satid=21574)