Launch and Operations
GOCE was launched from the Plesetsk Cosmodrome in northern Russia with a Rockot vehicle at 15:21 CET (14:21 UT). The Rockot 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 Briz-KM third stage developed for precise orbit injection. GOCE was launched into a Sun-synchronous dusk-dawn orbit with an inclination of 96.70° and an ascending node at 18:00. Separation from the launcher was 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 altitude control.
The first launch attempt on 16 March 2009, was aborted due to a malfunction with the launch tower. Liftoff occurred successfully at 14:21 GMT on 17 March 2009. The Rockot launcher delivered the satellite northward over the Arctic. About 90 minutes later, after one orbital revolution and two Briz-KM upper-stage burns, the spacecraft was successfully released into a circumpolar orbit at 280 km altitude with 96.7° inclination to the Equator. Soon after the separation, contact was successfully established with the satellite.
In February 2010 a fault was discovered in the satellite's computer, which meant controllers were forced to switch control to the backup computer. In July 2010, GOCE suffered a serious communications malfunction, when the satellite suddenly failed to downlink scientific data to its receiving stations. Extensive investigations by experts from ESA and industry revealed that the issue was almost certainly related to a communication link between the processor module and the telemetry modules of the main computer. The recovery was completed in September 2010: as part of the action plan, the temperature of the floor hosting the computers was raised by some 7°C – resulting in restoration of normal communications.
The first Earth global gravity model based on GOCE data was presented at ESA’s Living Planet Symposium, in June 2010.
In November, 2010, it was decided to extend the mission lifetime of 18 months, till the end of 2012, in order to improve the collected data.
As of November 2012 the orbit is being lowered from 255km to 235km to get higher resolution data. Fuel remains for another 50 weeks.
Read more about this topic: Gravity Field And Steady-State Ocean Circulation Explorer
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