The general objective of ACAP is to implement and investigate the so-called acceleration approach. This is a method to estimate the Erath's gravity field from precise orbit positions. The approach is based on Newton's second law of gravitation and directly relates the accelerations acting on a satellite to the gravity field of the earth. The accelerations acting on the satellite aren't observed directly and therefore they have to be calculated from orbit positions by means of numerical differentiation. In the frame of the project different approaches were tested to find the best configuration. After testing real data applications have been carried out with CHAMP (Challenging Minisatellite Payload) and GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) orbit products. As a result three different gravity field solutions based only on satellite positions were produced and are now available for download.
This project is funded within the Austrian Space Applications Program (ASAP) Phase VII by the Austrian Research Promotion Agency (FFG).