AIAA 2002-1703 Scalable Solar Sail Subsystem Design Considerations

Under recent contract to JPL for the New Millennium Space Technology 7 Program (ST7) AEC-Able Engineering (ABLE) developed a Scalable Solar Sail Subsystem (S). The S is a minimal mass propulsion subsystem that can be mounted to a general heritage spacecraft to provide continuous low level thrust. The design baseline is a 3-axis-stabilized 4-quadrant square sail with attitude controlled through gimbaling of the spacecraft on an extended boom. The work underway is unique in several aspects. It is the first sail system design effort: • To incorporate advanced CoilAble longeron technology as the sail masts, providing reliable deployment and structural robustness with minimum weight, • That proposes a configuration of flat tensioned membrane sails without the incorporation of catenaries, battens, or other structure, • Which mathematically identifies the significance of structural wrinkles on propulsive effectiveness, • To incorporate a 5-μm tear-tolerant CP1 membrane with close solar approach capability, • And incorporate panospheric camera technology to allow in-space measurement of sail and structure modes, and provide inspiring visual images to ground observers. The trades performed to arrive at the S design definition and the resulting configuration and performance versus size are reviewed. † Chief Research Engineer, Member AIAA ‡ Research Engineer, Member AIAA § Aerospace Technology Director, Member AIAA Copyright © 2002 by David M. Murphy. Published with permission by the American Institute of Aeronautics and Astronautics, Inc. Introduction Solar sail technology has been identified as enabling for many recent space mission concepts. Non-Keplerian orbits can provide unique perspectives in missions such as the Geostorm Warning Mission. Solar propulsion can also provide a significant cost savings for missions with high delta-V requirements such as the Heliopause Explorer and Solar Polar Imager. The Geostorm mission seems the best suited for initial usage of solar sail technology as the performance requirements for the sail subsystem are the least stressing of near term applications. The mission plan is to utilize photon pressure to allow a satellite to remain stable at a point closer to the sun than the L1 point. This would offer a valuable increase over the solar storm warning time provided by the aging NOAA satellite currently in service. The required sail performance is shown herein to be achievable with reasonable margins and reliability. A demonstration of this technology under NMP funding will ready sail technology for the GeoStorm mission and a series of progressively more challenging missions planned by NASA, NOAA, and the DoD. Many of the technologies required for solar sailing have yet to be demonstrated successfully in space. Attempts have been made to deploy both spinning (usually circular) and 3-axis stabilized membrane reflectors. The Achilles heel of many membrane system development efforts to date has been the complexity and lack of heritage of the technology configured for deployment. The S design utilizes a deployer with 100% flight success over more than 50 missions in the past three decades. ABLE has recently identified a method to optimize this deployable structure, the CoilAble, for the new family of lightly-load applications known as “gossamer” systems. The incorporation of new composite materials into the CoilAble allows the performance goals of