Analysis of phasing maneuver performed by a solar electric platform.

This thesis focuses on the problem of the phasing maneuver for a solar electric platform. By giving as input the orbital elements, in order to define the initial and final orbit, the position we want the satellite to reach, the phasing altitude, and the propulsive system, system mass and dymensions that characterize the platform, the program performs the phasing maneuver. The phasing maneuver controls the position of the solar electric platform in terms of longitude (for geostationary orbit), true longitude (equatorial orbit) or argument of latitude (inclined orbit). For the analysis of the maneuver to be performed, we start from chemical propulsion's manuver logic. The satellite performs the phasing maneuver with a first EOR (electric orbit raising) raising its semimajor axis by an input values (phasing altitude). Then, the platform waits on a waiting orbit and, in the end of the maneuver, it returns to the starting orbit with a second EOR. The main goal of this first part of the thesis was to perform a change of reference system from ECI (Earth - Centered Inertial) to ECEF (Earth - Centered, Earth - Fixed) so that the program can perform the maneuver controlling the longitude. In the second part of the thess, in order to optimize the maneuver, the waiting phase has been avoided. In this way, the solar electric platform is able to reach the desired position by perfoming two consecutive EOR maneuvers. In this case the phasing altitude is no longer an input, but an output. To determine the phasing altitude needed to reach the desired position, the program interpolates data. Furthermore, the program saves the various interpolation data (position reached and phasing altitude) in an EXCEL file, in order to be able to reduce the computational cost when the orbital parameters of a subsequent simulation are equal to a simulation already carried out. In the end, to validate the results obtained, STK (Satellite Tool Kit) was used to perform various simulations.