Description: A team of CU Aerospace and the University of Illinois at Urbana-Champaign proposes the Phase I design and development of a 25 kg spacecraft for initial flight test of a 2,500 m^2 UltraSail demonstrator, called I-Sail. This technology represents a next-generation high-risk, high-payoff solar sail system for the launch, deployment, stabilization and control of very large (km^2 class) solar sails, enabling very high payload mass fractions for interplanetary and deep space spacecraft. UltraSail is an innovative, non-traditional approach to propulsion technology achieved by combining propulsion and control systems developed for formation-flying microsatellites with an innovative solar sail architecture to achieve controllable sail areas approaching 1 km^2, sail subsystem area densities less than 5 g/m^2, and thrust levels many times those of ion thrusters used for comparable deep space missions. Phase I effort will focus on the design of this next generation I-Sail demonstrator, a two-order of magnitude scale up from the prior subscale 20 m^2 CubeSail hardware, along with potential mission selection with requirements. I-Sail represents the next stage of risk reduction for the UltraSail technology prior to full scale deep space development in the next decade.

Benefits: The NASA Technology Roadmap calls for an in-space demonstration of a 2500 m2 sail to Earth escape in the 2019-2022 timeframe; the proposed I-Sail can meet this NASA goal. Examples of solar sail missions include: pole sitter, Earth-Moon Lagrange point, Earth-Sun Lagrange point, deep space science, outer planet rendezvous, and solar polar. UltraSail is potentially useful for a range of robotic NASA missions of relevance to NASA's science and exploration goals ranging from Near-Earth to Sun-Earth Lagrange point L1 to Mars to the Kuiper Belt, an interstellar probe, and multiple NEO rendezvous missions. The very high payload mass fraction potential for the UltraSail concept (~60%) coupled with highly efficient packaging and high thrust from large sail area results in economical, high-performance missions. The use of micro-satellites coupled with UltraSail techniques permits low-cost mission development before committing to much larger systems.

A number of science mission concepts have been identified that make optimum use of solar sails as the next phase in the development of solar sail propulsion as the go-to technology for high C3 missions. UltraSail has military applications for earth-observing missions at high orbit where stationary observing is useful, e.g. pole-sitting missions. Also, NOAA and NSF have strong interests in the science that can be returned using sails in non-Keplerian orbits and at Lagrange points. Mission concepts enabled by solar sails include: Solar Polar Imager, GeoSail, and Heliostorm (NOAA Geostorm). Each of these mission concepts have been envisaged assuming the successful development of the relevant technological capability, and they are not generally achievable without access to reliable solar sail propulsion and control.