Gravity Field and Steady-State Ocean Circulation Explorer

The Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) is an ESA satellite to be launched 27 October 2008 at 15:21 CET [cite web|url=http://www.esa.int/SPECIALS/GOCE/SEMRGH6EJLF_0.html|title=GOCE team gearing up for new launch date|date=2008-10-02|publisher=ESA|accessdate=2008-10-04] .Its main payload is the Electrostatic Gravity Gradiometer (EGG) to measure the gravity field of Earth.

Its arrow shape and fins help keep the satellite stable as it flies through the wisps of air still present at an altitude of 260km. The low orbit and high accuracy of 1 mGal will improve the known accuracy of the geoid to 1-2 cm at a spatial resolution better than 100 km [http://www.esa.int/esaLP/ESAYEK1VMOC_LPgoce_0.html ESA's GOCE homepage visited 20080513] . To increase resolution, the satellite will fly in an unusually low orbit; an electric engine will make up drag losses to compensate for the residual drag losses.

GOCE data will have many uses, probing hazardous volcanic regions and bringing new insight into ocean behaviour.

The latter, in particular, is a major driver for the mission.

By combining the gravity data with information about sea-surface height gathered by other satellite altimeters, scientists will be able to track the direction and speed of geostrophic ocean currents.

GOCE will be launched from the Plesetsk Cosmodrome in northern Russia with a Rockot vehicle. TheRockot is a modified SS-19 intercontinental ballistic missile that was decommissioned after the Strategic Arms Reduction Treaty. The launcher uses the two lower liquid fuel stages of the original SS-19 and is equipped with a third stage developed for precise orbit injection. GOCE will be launched into a Sunsynchronous dusk-dawn orbit with an inclination of 96.70˚ and an ascending node at 18:00. Separation from the launcher will be at 295 km. The satellite’s orbit will then decay over a period of 45 days to an operational altitude, currently planned at 270 km. During this time, the spacecraft will be commissioned and the electrical propulsion system will be checked for reliability in attitude control. [ http://www.esa.int/esapub/bulletin/bulletin133/bul133c_fehringer.pdf Esa Bulletin n. 133, February 2008 ]

References

ee also

* Gravity Recovery and Climate Experiment (GRACE)

External links

* [http://www.esa.int/SPECIALS/GOCE/index.html ESA GOCE site]
* [http://www.esa.int/esaLP/LPgoce.html ESA's gravity mission GOCE]
* [http://www.esa.int/SPECIALS/Operations/SEMN4Z8L6VE_0.html GOCE page at ESA Spacecraft Operations]
* [http://solarsystem.nasa.gov/missions/profile.cfm?MCode=GOCE GOCE Mission Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]
* [http://news.bbc.co.uk/1/hi/sci/tech/6919016.stm BBC News story]