A ubiquitous world can be achieved through a world-wide information communication network, making the most use of wireless access technologies. The fact is that an enormous number of radio base stations and terminals are required, and accordingly their impact on the environment cannot be ignored any longer. For example, the gross energy consumption of the hardware- even only in Japan, has already reached up to a level requiring further nuclear power plants. The radio stations are consuming the largest power; hence the circuit/equipment technologies to drastically improve power efficiencies have become all the more important.

This keynote speech introduces some practical technologies to which this speaker was engaged in research and development, and overviews the future trends of various related studies and current developments towards reducing the environmental loads from a standpoint of microwave fields.

World's First Demonstration of Solar Power Sail by "IKAROS" toward Jupiter System Exploration

A Solar Power Sail is a Japanese original concept that gets electricity from thin film solar cells on the sail membrane in addition to a photon propulsion by solar sail.

JAXA successfully achieved the world's first solar power sail technology by IKAROS mission in 2010. The 200m2-span sail was deployed and kept extended by centrifugal force of the spacecraft rotation. IKAROS succeeded in accelerating and controlling the orbit by actively exploiting solar radiation pressure, and thus became the world's first actual solar sailer flying an interplanetary voyage. It also demonstrated thin film solar power generation.

This paper presents the design of IKAROS solar sail system, operation results and introduces a perspective of this new technology to apply to the next generation mission toward Jupiter and Trojan asteroids.