This thesis is separated into two parts. The first part is about satellite orbits forspace-based gravitational wave detectors. Gravitational waves are ripples in thefour-dimensional spacetime and were firstly predicted by Albert Einstein. They canbe caused by astrophysical events (e.g. merging black holes, stellar explosions) andmanifest as length changes between objects, for example, satellites. The order ofmagnitude of the relative length changes corresponds approximately to the size ofan atom over a measurement distance between Sun and Earth. However, even thistiny effect can be measured with laser light, interferometrically. In this thesis theconstruction of satellite constellations in the vicinity of the so-called Lagrangianpoints is investigated, which might be stable enough over the mission duration toallow interferometric measurements between the spacecrafts. Therefore, the fundamental dynamics of single objects in the proximity of Lagrangian points are studied,followed by attempts to construct constellations by combining different trajectories.Finally, numerical optimization techniques are applied to further improve the constellations.The second part of this thesis is concerned with an instrument for the GRACEFollow-On mission. This planned mission consists of two satellites in a low Earthorbit, which shall measure Earth’s gravity field. Therefore, the inter-satellite distance fluctuations need to be determined very precisely in the frequency range from2 mHz to 100 mHz. For this purpose the Albert-Einstein-Institute develops in cooperation with industry and international partners a Laser Ranging Interferometerwith a target precision better than 0.001 millimeter. An overview about the workingprinciple of the instrument as well as the purpose of single components is presented.The contribution of various perturbations like spacecraft attitude jitter on the performance is computed. Finally, simulation results show how various misadjustmentsof components influence the measurements