The concept of Solar Power Satellite (SPS) is to utilize the space surrounding the earth to tap energy for human society. SPS generates electric power in space using the solar radiation energy and converts it to the microwave power beam to the receiving antenna on the ground. The microwave power is converted to the commercial utility power. SPS has a great potentiality for the large-scale clean energy system to replace the fossil energy plants. To realize the SPS concept, scientific research is widely required for the associated technologies, environmental issues, and social aspects. This special issue is devoted to report the current status of research for microwave power transmission, high voltage solar array, ultra-large antennas, microwave-ionosphere interactions, and construction and structure. This status report will hopefully be a help in promoting the SPS-related research in the field of vacuum science and technology.
