Autonomous Phasing Maneuvers in Near Circular Earth Orbits

Autonomous, reliable and efficient guidance systems for new small satellites al low for the development and implementation of missions and technologies, such as on orbit servicing, that would be crucial for the evolution of space sector. In this context, this work refers to the problem of impulsive reconfiguration of rel ative motion between a chaser active spacecraft and a target passive one, in near circular Earth orbits. This procedure searches for impulse magnitudes and cor responding times of application to reach an aimed final relative configuration, in a fixed time window, while minimizing propellant consumption. Relative orbital elements are chosen as state variables and closed form solutions are preferred over numerical methods, because of their predictability and computational efficiency. The proposed solutions are inspired from the AVANTI flight demonstration, but specific strategies to address the case in which the relative planar motion change is dominant in the along track direction (rephasing scenarios) are introduced here. The new strategies are compared to the ones used in the AVANTI demonstration in different scenarios. Similar solutions are obtained for small changes of rela tive mean longitude, proving the flexibility of the new schemes. As expected, for scenarios with large along track changes, the new strategies specifically designed for these cases, outperform the original strategies (with δv savings almost always above 50%). The optimality of the proposed solutions is checked by comparison with the actual global optimum found numerically. Results show that the δv is within 1% from the optimum in 95.3% of cases and always within 4.5%. The ul timate contribution of this work is to provide a simple and effective algorithm to evaluate the convenience to combine in-plane and out-of-plane maneuvers, along with general theoretical understanding of 3D reconfiguration.