# Gravity Field and Steady-State Ocean Circulation Explorer

> ESA satellite which mapped Earth's gravity field

**Wikidata**: [Q258697](https://www.wikidata.org/wiki/Q258697)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/GOCE)  
**Source**: https://4ort.xyz/entity/gravity-field-and-steady-state-ocean-circulation-explorer

## Summary
Gravity Field and Steady-State Ocean Circulation Explorer (commonly GOCE) was an ESA research satellite that mapped Earth's gravity field and studied steady-state ocean circulation. Launched on 2009-03-17, GOCE used a zero-drag design with precise accelerometers and a gradiometer to follow a near-geodesic trajectory for high‑precision gravity measurements.

## Key Facts
- GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) was launched on 2009-03-17 at 14:21:14 UTC from Plesetsk Cosmodrome Site 133. (COSPAR ID: 2009-013A)
- Operator: European Space Agency (ESA). GOCE was part of ESA’s Earth Explorer Programme.
- Mass (launch weight): 1,052 kg; payload mass: 205 kg.
- Physical dimensions: length 5.307 m, width 2.366 m, diameter 1.15 m.
- Spacecraft class/instance: research satellite; zero-drag satellite; artificial satellite of the Earth; former entity.
- Launch vehicle: Rokot (with Briz-KM as space tug). 
- Manufacturers and major contractors: Alenia Spazio (general contractor), Astrium (spacecraft bus), Alcatel Space (gradiometer), Office National d'Études et de Recherches Aérospatiales (ONERA) (accelerometer).
- Service entry into operations: 2009-09-29; service retirement due to fuel starvation: 2013-10-21.
- Loss of signal recorded on 2013-11-10; atmospheric entry / orbital decay occurred on 2013-11-11 (time of decay 00:16 UTC; approximate decay location lat −56°, lon −60°).
- Capital cost (spacecraft, launch vehicle, operations) reported as €350,000,000 (point in time: 2013).

## FAQs
### Q: What was GOCE's primary purpose?
A: GOCE was an ESA research satellite designed to map Earth's gravity field and to study steady-state ocean circulation, using very precise inertial sensors and a gradiometer.

### Q: When was GOCE launched and when did its mission end?
A: GOCE was launched on 2009-03-17 and entered service on 2009-09-29. The mission was retired due to fuel starvation on 2013-10-21; the satellite lost signal on 2013-11-10 and re-entered the atmosphere on 2013-11-11.

### Q: What was special about GOCE's design?
A: GOCE was a zero-drag satellite, meaning it used an active control system so its payload followed a near-geodesic path through space to enable very precise gravity measurements. It carried a gradiometer and accelerometers supplied by specialist contractors.

### Q: Who built and operated GOCE?
A: The mission was operated by the European Space Agency. Major contractors included Alenia Spazio (general contractor), Astrium (spacecraft bus), Alcatel Space (gradiometer), and ONERA (accelerometer).

### Q: How large and heavy was GOCE?
A: GOCE had a launch mass of 1,052 kg, a payload mass of 205 kg, length 5.307 m, width 2.366 m, and diameter 1.15 m.

## Why It Matters
GOCE provided a focused capability to measure Earth's gravity field with high precision using a purpose-built, zero-drag satellite architecture. Accurate gravity field models are fundamental for understanding geophysical processes and for improving models of ocean circulation, which underpin studies of sea level, ocean dynamics, and geodesy. GOCE’s instruments — including a dedicated gradiometer and accelerometers — were designed to operate with minimal non-gravitational disturbances so the spacecraft could closely follow a geodesic trajectory and isolate gravitational signals. As part of ESA’s Earth Explorer Programme, GOCE demonstrated the value of targeted, high-precision spaceborne geodetic measurements and supplied data products used by scientists and operational services. Its multi-year operational phase (2009–2013) and controlled measurement approach made it a distinctive contribution to Earth observation and gravity science before its planned end-of-mission re-entry in November 2013.

## Notable For
- Being an ESA Earth Explorer research satellite specifically built to map Earth's gravity field and study steady-state ocean circulation.
- Using a zero-drag design so the payload followed a near-geodesic trajectory for high-precision gravity measurements.
- Carrying a dedicated gradiometer (manufactured by Alcatel Space) and accelerometers (ONERA) as primary instruments for gravity sensing.
- A multi-year operational mission from service entry in September 2009 until retirement due to fuel starvation in October 2013, with atmospheric re-entry on 2013-11-11.
- Significant capital cost reported at €350 million covering spacecraft, launch vehicle, and operations (2013 point in time).

## Body

### Overview
- Full name: Gravity Field and Steady-State Ocean Circulation Explorer (GOCE).
- Aliases: GOCE, Earth Explorer 1, Global Ocean Circulation Explorer.
- Short description (Wikidata): ESA satellite which mapped Earth's gravity field.
- Part of: Earth Explorer Programme (ESA).

### Design and specifications
- Launch mass (criterion: launch weight): 1,052 kg.
- Payload mass: 205 kg.
- Dimensions: length 5.307 m; width 2.366 m; diameter 1.15 m.
- Power: spacecraft solar array listed with a qualified amount of 1,600 (as provided by the mission source).
- Spacecraft class: research satellite; zero-drag satellite; artificial satellite of the Earth; categorized as a former entity after mission end.

### Payload and instruments
- Primary instruments included a gradiometer (Alcatel Space) and accelerometers (ONERA) as referenced by manufacturers.
- The zero-drag concept was employed so the payload followed a geodesic path to isolate gravitational signals.

### Launch and flight
- Launch date and time: 2009-03-17 at 14:21:14 UTC.
- Launch site: Plesetsk Cosmodrome Site 133.
- Launch vehicle: Rokot (Rokot launch system) with Briz-KM as the space tug.
- COSPAR ID: 2009-013A; NSSDC/NSSDCA ID recorded as 2009-013A.

### Mission timeline and status
- Service entry: 2009-09-29 (entered operational service).
- Service retirement: 2013-10-21 due to fuel starvation.
- Loss of signal recorded on 2013-11-10.
- Atmospheric entry / orbital decay: 2013-11-11 at 00:16 UTC; decay location reported approximately lat −56°, lon −60°.

### Operators, contractors, and cost
- Operator: European Space Agency (ESA).
- Manufacturers / contractors:
  - Alenia Spazio — general contractor.
  - Astrium — spacecraft bus.
  - Alcatel Space — gradiometer.
  - Office National d'Études et de Recherches Aérospatiales (ONERA) — accelerometer.
- Capital cost reported: €350,000,000 (covering spacecraft, launch vehicle and operations; point in time: 2013).

### Data and resources
- Official ESA mission pages: https://www.esa.int/goce and https://earth.esa.int/eogateway/missions/goce
- Related imagery: mission-scale images and gravity-anomaly visualizations are archived under the GOCE category on Wikimedia Commons.

### Identifiers
- SCN: 34602.
- Freebase ID: /m/07zrrf.
- Wolfram language entity code: Entity["Satellite", "34602"].
- Additional catalogue and encyclopedia identifiers noted in mission records.

(End of entry)

## References

1. [Source](https://space.skyrocket.de/doc_sdat/goce.htm)
2. [Source](https://www.esa.int/Applications/Observing_the_Earth/FutureEO/GOCE/Facts_and_figures)
3. Jonathan's Space Report
4. The Deorbiting of GOCE - A Spacecraft Operations Perspective
5. [Source](https://www.eoportal.org/satellite-missions/goce#spacecraft)
6. [Source](https://www.eoportal.org/satellite-missions/goce#mission-status)
7. Freebase Data Dumps. 2013
8. [Source](https://www.esa.int/Newsroom/Press_Releases/ESA_s_GOCE_mission_comes_to_an_end)
9. [Source](https://www.esa.int/Enabling_Support/Operations/GOCE)
10. Gravity mission to launch
11. Quora