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The Solar Photon Sail Comes of Age

Abstract Solar photon sailing, spacecraft propulsion by the pressure of sunlight, has long been a theoretical concept. During 2010, two successful missions—one in Earth orbit and one in deep space—demonstrated the utility of the concept and advanced its technological readiness level. This paper reviews the history of the solar sail, near term mission possibilities and possible far-future developments. Both recent missions: the NASA Earth-orbital Nanosail D2 drag sail and the Japanese JAXA Ikaros interplanetary technology demonstrator are discussed. Used with close solar flybys or solar-orbital laser power stations, the photon sail is one of our few candidates for extrasolar and interstellar propulsion. It may also have application to Earth defense from asteroid impacts and terrestrial climate control.