INDIRECT BASED SHADOW MODELLING WITH WARM-UP TIME FOR PERTURBED ORBIT

Low thrust solar powered missions are challenging for their requirement of long duration missions with extended periods of thrusting. The complexity of the mission design and trajectory optimization is enhanced by the occurrences of eclipses when the solar arrays generate no power for the duration of the eclipse forcing the spacecraft to coast and leaving the essential systems to be supported by the battery. Therefore, the charge depletion of the battery and the temperature drop of the engine are consequent events that deter automatic retrieval of thrusting capability even when the spacecraft just ventures out of the shadow region. This is called as warm up period which typically depends on the duration of the eclipse. Though important in practice, warm up time has never been formally included as a factor at the level of trajectory optimization. This work shows the capability of accommodating such discrete events like warm up time in the indirect optimization to obtain a more realistic eclipse constrained fuel-optimal solution for the first time.