The Gravity Field
and Steady-State Ocean Circulation
Mission (almost an acronym
...) of the European Space Agency
. The satellite
will give new and more accurate measurements of the Earth
(that is, the 'actual' shape of the Earth
, lumps and bumps included), which will in turn improve our knowledge of the Earth's gravity field
and interior physics
. The Goce mission is intended to measure the entire Earth's geoid
, by using a new method involving GPS
. This should lead to advances in oceanography
, solid-earth physics
, and geodesy
The data will be gathered using a Gradiometer, made using 3 pairs of 3-axis accelerometers. This allows the satellite to measure the gravitational pull very accurately in 3-dimensions (and so will produce a 3-dimensional map of the Earth's gravity field). Both low and high resolution data will be produced for different applications: The geoid will be mapped to an accuracy of 100 km (doesn't sound like much, but over the entire planet, thats a whole lot of data...), specific oceanographic studies, mainly investigating the flows of various currents, will be undertaken with an accuracy of 1 cm, and the vertical movements of ice-sheets will be measured to within 2 cm accuracy.
All of these investigations will make use of existing GPS data. However, by mapping the Earth's geoid, Goce will then be able to make height-measurements of land around the world that are completely objective. At present, different countries and continents use differing height measuring systems. After Goce, it will be possible to create a unified height measurement database, and so land elevations can be meaningfully compared between (say) Japan and Zimbabwe. This has some very useful applications, not only because it provides more accurate information for geographers and map makers, but because this information can then be used by various companies (for example satellite TV providers, mobile phone satellites) to more accurately target specific areas. Basically, although it relies on GPS, Goce will eventually be improving on the existing system.
At present, Goce is scheduled to be launched in 2005, and remain active for 20 months. It will weigh approximately 1000 kg at launch, and be launched from a Rockot launcher (not a typo, a joint Russian/European launcher..), or a similar small-payload, unmanned launcher. Communication will be via 2 S-band antennas: Goce will be capable of recieving telecommands at a rate of 2 kbit/s, and transmitting data at 850 kbit/s. The satellite will be controlled from ESA's ESOC operations centre, and the data will be recieved in Kiruna, Sweden, where it will be subjected to preliminary processing.