Solar Sail

solar sail [′sō·lər ′sāl]

(aerospace engineering)

A surface of a highly polished material upon which solar light radiation exerts a pressure. Also known as photon sail.

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Solar Sail 

(or photon sail), a proposed means of spacecraft propulsion. It consists of very thin opaque sheeting—for example, a metallized polymeric film—that is set up on the vehicle in space and is capable, over a rather long period of time, of imparting a substantial speed to the vehicle owing to the action of solar radiation on the sail (seeLIGHT PRESSURE). A limitation on the use of a solar sail is that it can move the spacecraft in only one direc tion: away from the sun. Moreover, the force exerted by the solar radiation on the sail is small and decreases in inverse proportion to the square of the distance from the sun. The solar sail may find application in interplanetary flights.