Optimal Near Sun Synchronous Orbital Design of a Nadir-Pointing Cubic Satellite with the Purpose of Thermal Load Control

Orbital parameter assessment as an integral part of a mission design has a parental effect on other subsystems of a satellite. The design and performance requirements of subsystems are intensely coupled with the orbital parameters. Additionally, mission requirements impose some constraints on the orbit design. For instance, in Earth Observation missions, the orbit should be designed in a way that keeps its local time in an allowable range during the mission lifetime. This allowable range of the local time depends on the imaging requirements and the quality of the received light from the region.

Some parameters such as eclipse time, sun incidence angle, albedo, and earth IR depend on satellite orbital parameters. In this study, by doing a dynamic simulation of every aforementioned parameter over the satellite lifetime, investigation of an objective function and some constraints have been provided for every second of the mission. There are two subsystems of a satellite which are mostly under the influence of the orbital characteristics: Thermal Control Subsystem and Electrical Power Subsystem. Moreover, these two subsystems are strongly in interaction with each other so that considering only one of them without the other one is not analytically and practically possible. This paper mainly aims at seeking for an optimal near sun-synchronous orbit for a nadir-pointing satellite using Evolutionary Algorithms. Mission and Power requirements are considered as constraints to be satisfied as well as controlling thermal load applied on the satellite. A computational code has been developed to simulate the performance of the satellite mission characterized by high accuracy.