 Gravity gradiometry

Gravity gradiometry measures spatial differences of gravitational acceleration. Two simultaneous measurements along a unit vector $\mathbf{e}$, separated by $L\mathbf{e}$, giveThis measures one directional component of the tidal tensor, not its whole matrix. Any identical platform acceleration cancels in the difference. Unequal instrument responses, changing geometry and rotating reference frames can spoil that cancellation. For a large baseline, the quotient is an average of the directional tidal tensor along the baseline, rather than its exact value at one point.

Gravity gradiometry is a measurement technique used to detect and quantify variations in the gravitational field of the Earth or other celestial bodies. It does this by measuring the gradient or change in gravitational acceleration over a specific distance, rather than measuring gravitational acceleration at a single point. ### Key Concepts: 1. **Gravity Gradient**: The gravitational field is not uniform; it varies with location due to differences in geological structures, such as mountains, valleys, and different densities of rocks and sediments.