Comparing Solar Sail And Solar Electric Propulsions For Propulsive Effectiveness In Deep Space Missions

A promise of new sail technology is generating renewed interest in solar sailing. Ultra light-weight carbon films with built-in stiffness for example is predicted to result in a sail with very low area density (similar to2 g/m(2)) and high temperature tolerance. There have been many prior solar sail mission studies suggesting the usefulness of solar sails for a gamut of planetary and space physics missions. The question, "how does SAIL compare with SEP?", has often been raised by NASA program evaluators but was never answered in a satisfactory manner. The results of a brief study to answer this question are presented. This paper considered a reasonably broad set of NASA missions of interest. The goal of the study was to compare in a logical and uniform manner the effectiveness of each propulsive device (SAIL or SEP) in performing the given set of missions. The study selected the use of a Delta II/7925 launch vehicle and set the same payload goal (net mass) of 500 kg for each to deliver. Then the flight time required by each device becomes the single performance discriminator.