Recent advances in computational techniques

The determination of very precise orbits and geodynamic parameters from laser tracking data requires the continual development and improvement of the software systems and computational techniques. Computational accuracies at the few centimeter level are presently required to match the performance of the present day laser ranging systems and altimeters and in the next few years the accuracies are expected to increase further. The major error sources in orbit determination are briefly discussed and the present and future modeling activities needed to meet the accuracy requirements of the next few years are described.