An analytic expression for the gravitational mass attraction force and force gradients at a point due to a right-angled parallelepiped (brick) with homogeneous density is presented. Using a LISA proof-mass geometry as a test case, force and force gradient simulation results for the analytical expression are compared to a single point mass approximation.
Free space optical communication is of interest to NASA as a complement to existing radio frequency communication methods. The potential for an increase in science data return capability over current radio-frequency communications is the primary objective. Deep space optical communication requires laser beam pointing accuracy on the order of a few microradians. The laser beam pointing approach discussed here operates without the aid of a terrestrial uplink beacon. Precision pointing is obtained from an on-board star tracker in combination with inertial rate sensors and an outgoing beam reference vector. The beaconless optical pointing system presented in this work is the current approach for the Integrated Radio and Optical Communication (iROC) project.
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