Gravity gradiometry: From Loránd Eötvös to modern space age

Loránd Eötvös' torsion balance yields the local structure of the earth's gravity field with very high precision, still comparable to present days standards. The recently launched NASA satellite mission GRACE and the approved ESA mission GOCE (launch in 2005) apply the same measurement principle in space. It counteracts the natural attenuation with growing distance from the earth's surface of the gravitational attraction. As a consequence, even from space the global gravity field will be mapped with unprecedented resolution and accuracy. Also temporal variations due to mass changes in the atmosphere, oceans, ice covers, groundwater tables and inside the earth are expected to be discernible. Geodesy, solid earth physics, oceanography and sea level research will greatly benefit from the detailed knowledge of the earth's gravity field.