Optimal mission scheduling for hybrid synthetic aperture radar satellite constellation based on weighting factors

Abstract

Hybrid synthetic aperture radar (SAR) satellites, unlike active SAR satellites using phased array antennas, mainly acquire images using mechanical beam steering and, to some extent, through electronic beam steering. Therefore, the image acquisition capability of a hybrid SAR satellite is affected by its agility. An optimal mission plan considering the image downlink and command uplink related to mission operation and maneuvering characteristics for image acquisition is required to maximize the capability of such a satellite. In this study, we developed a model of the timeline elements needed for image acquisition using a SAR satellite and a mission plan considering multiple passes of SAR constellation satellites. The proposed mission plan involves optimization using dynamic programming and a genetic algorithm. Dynamic programming is applied to enable the satellite to image the area of interest (AoI) as effectively as possible in a single pass. In addition, the mission plan was optimized by adjusting the weighting factor of each target using the genetic algorithm to enable targets in the AoI to be imaged quickly in multiple passes. The mission plan was implemented according to the proposed technique, and it was confirmed that the method of assigning the weighting factors of the targets could affect the number of passes required to image all the targets in the AoI. The mission performance was also improved compared to that of the conventional method in terms of minimizing the number of mission passes and considering a mission plan with multiple passes.