GOCE Configuration and Mission Instrumentation (Payload):
GOCE is a slim rigid structure having no moving parts. The overall weight of the octagonal spacecraft is about 1050 kg and it is approximately 5m long and 1m in diameter. With an inclination of 96.70 degrees and an ascending node at 18:00, the GOCE will be launched into a Sun synchronous dusk-dawn orbit. The spacecraft will have an altitude of about 250km, after separation from the launcher, with a hibernation currently planned at 270 km.
The scientific instruments of the GOCE satellite mission consist of:
1. Electrostatic Gravity Gradiometer ( EGG)
2. SSTI (Satellite-to-Satellite-Tracking)
3. Laser retroreflector
1. The Electrostatic Gradiometer or the EGG is the main scientific instrument that will measure the gravity field of Earth. The Gradiometer has 3 pairs of identical accelerometers, which form three gradiometer arms and are mounted on an ultra-stable structure. Each pair of accelerometers is separated by a distance of about 0.5 m.
The SSTI instrument delivers so-called pseudo-range and carrier phased measurements, both on GPS frequencies at 1Hz. With an advanced dual-frequency 12-channel GPS receiver and an L-band antenna, the SSTI is capable of acquiring signals broadcasted from up to 12 spacecraft in the GPS constellation simultaneously.
This instrument helps the global network of ground-based stations track the orbit of the GOCE spacecraft accurately, with the help of Satellite Laser Ranging Service.