Power-Optimal Guidance for Planar Space Solar Power Satellites

Abstract

This paper presents power-optimal guidance for a planar space solar power satellite (SSPS).Power-optimal guidance is the attitude trajectory that maximizes the solar power transmitted by the SSPS. Maximizing the transmitted power simultaneously maximizes the cumulative energy delivered to the receiving station. Planarity couples the orientations of the SSPS's photovoltaic and antennas surfaces. Hence, the transmitted power only depends on the relative geometry between the SSPS, Sun, and receiving station. The orientation that maximizes power transfer changes as this relative geometry changes. Both single and dual-sided SSPS architectures are considered. A single-sided SSPS has one photovoltaic surface and one antenna surface. A dualsided SSPS is a single-sided SSPS with at least one additional photovoltaic or antenna surface. Geometric arguments show that a dual-sided SSPS has superior performance to a single-sided SSPS. Power-optimal guidance is then determined numerically for several examples, including for an SSPS in GEO. These examples emphasize important solution properties, including the need for large slew maneuvers, and show that even though system efficiency decreases as orbit altitude decreases, reduced path losses actually increase the total amount of received energy per unit aperture area. This has significant system implications for future space solar power missions. Nomenclature A = area -m 2 AF(φ) = phased array factor

Investigation of Equatorial Medium Earth Orbits for Space Solar Power

“…We remark that Problem 1 intentionally neglects both orbital maneuvering costs (for formation maintenance and stationkeeping) and attitude maneuvering costs (for slewing and rejecting disturbance torques/desaturating momentum devices). Preliminary studies for space vehicles with modern electric propulsion thrusters for orbit and attitude control have shown that the propellant masses required for orbital [33] and attitude [37] maneuvering in the absence of external perturbations are likely a negligible fraction of the total space vehicle mass over a 10-15 year lifetime. In contrast, the power transmission efficiency (by way of the geometric efficiency) is a significant contributor to the system's LCOE.…”