Tethered solar power satellite

A solar power system, in which a large flat panel with a capability of power generation and transmission is suspended by multi-wires, is proposed as an innovative Solar Power Satellite (SPS). This SPS concept is highly robust and potentially low cost, with special features in the integration, construction, attitude control, heat management, and evolutional development strategy. The power generation and transmission panel is composed of a huge number of perfectly equivalent modular panels, that is essential for low-cost mass production. The electric power generated by the solar cells at the surface of each module is converted to the microwave power in the same module. There are no wired signal/power interfaces between the modules. All modules are controlled by a wireless LAN system. The wireless interface between the modules leads to easy deployment and integration. Since the solar light is not concentrated in this configuration, quite different from the recent SPS concepts equipped with condensing lens or mirrors, the temperature of the module is kept within an operational range for the commercial electrical parts without any active heat rejection. The attitude in which the microwave transmission antenna is directed to the ground is automatically maintained by the gravity gradient force of the suspension system. The tethered panel is composed of individual tethered subpanels which are loosely connected to each other. This configuration enables an evolutional construction in which the function of the SPS grows as the construction proceeds. A scale model of the tethered sub-panel can be used for the first step demonstration experiment of the SPS in the near future. The demonstration experiment can verify the power transmission from the orbit to the ground, which is the most important subject at this stage of the SPS research. This concept of the SPS has disadvantages that the power to the ground varies with the local time and the working ratio is 64 % on the average as compared with the sun-pointing type SPS, but they are well compensated by the advantages in the electrical, mechanical, thermal and integration aspects.