Many applications need an “enough” precise and resolute gravity field. Such application fields span from science (Oceanography, Geophysics and Environment) to institutional (Seismic, Volcanic and landslide hazard mitigation) and commercial (oil prospecting, civil engineering). Airborne gravimetric survey can provide nowadays, in areas with no ground infrastructures, a gravity recovery at the level of 15 mGal which in turn can provide at most a geoid with accuracy of 20 cm.
It is estimated an improvement with GALILEO by a factor of 3 or 4, even in areas with no ground support, while in infrastructured areas there is a hope to reach accuracy in the order of 0,1 mGal on spatial scales of ~ 10 km. All these targets can be hit much more easily with the availability of data from ESA mission “GOCE”.
The idea underlying the GAL project is the study and development of a state of the art methodology for determination of precise and high-resolution gravity field models through precise kinematic airborne gravimetric with GPS, EGNOS, GALILEO and strapcdown Inertial Measurement Units (IMUs) and its further integration with GOCE global models. The GAL concept is based on the combination of satellite-derived global gravity models with airborne-derived local models. GOCE measurements will provide the global gravity model with 1-2 mgal accuracy (1-2 cm geoid accuracy) at 100 km wavelengths and longer, while the airborne ranging and inertial measurements will provide the local ones at comparable accuracy with resolutions ranging from 200 to 1 km.
A multi-constellation data processing approach will be used for the combined exploitation of GPS and GALILEO implementing positioning techniques like Precise Point Positioning. GAL project could enable gravity field measurements recovery at marginal cost in many non-surveyed areas in the world, in particular in developing countries.