GOCE, scheduled for launch in 2006, is the second Earth Explorer satellite to be developed as part of ESA's Living Planet Programme. Over just 20 months this mission will provide unprecedented high-resolution and high-accuracy global models of the Earth's gravity field and of the geoid.
Because the Earth is not a homogeneous sphere, the force of gravitational acceleration 'g' varies significantly from place to place on the surface of the planet. This irregular gravity field shapes a virtual surface at mean sea level called the 'geoid'. The GOCE mission will provide a better understanding of the Earth's gravity field and its associated geoid, significantly advancing our knowledge in areas of oceanography, solid-Earth physics, geodesy, glaciology and climate-change research. The data resulting from this high-accuracy gravity field mission will also have numerous 'down-to-Earth' applications, for instance, an improved geoid model will be used for surveying and the construction industry.
The workshop held last week heralded an important milestone in the development of the GOCE mission. During the two and a-half-day event around 60 presentations, covering many aspects of the mission, were given and discussed in depth. In particular, the impact of the recently modified drag-free and attitude control system of the satellite was assessed by the community. Last year, the design of the satellite was modified slightly in order to reduce the risk of a launch delay. It was confirmed at the workshop that these design changes would also significantly improve the robustness of the mission whilst having only a marginal impact on the quality of the derived gravity and geoid models. The workshop concluded that all of the mission objectives would still be met.
The main area of application for the GOCE mission is associated with ocean circulation, which was one of the main themes of the workshop. Presentations at the workshop revealed that although the US-German GRACE satellite, launched in 2002, is currently providing gravity field data, there is much potential for improving ocean circulation models. Data from GOCE will complement that from GRACE since the GOCE will provide higher resolution. It is now felt that the impact of the use of a high-resolution geoid may be even larger than that which was estimated when GOCE was originally selected for development. The contribution of GOCE data to the field of oceanography is considered to be so important that existing altimetry records may need to be reprocessed with the latest state-of-the-art models ready for the match-up with GOCE data.
The workshop highlighted the need for special and dedicated care of how the GOCE data is to be processed to ensure that the best gravity field model can be delivered to the scientific users. A strong recommendation was made to conceive a so-called 'User Toolbox' to help users in specific application areas best exploit GOCE data. In addition, the EU GOCINA project will support the mission by educating and preparing the community in using GOCE data for oceanography.
The Second International GOCE User Workshop proved to be an extremely informative and stimulating event that paves the way for the final stages of development for the GOCE mission.