Attitude Control for Circumnavigating the Sun with Diffractive Solar Sails

A solar sail making use of the physics of diffracted light enables the transfer of optical to mechanical momentum for in-space propulsion. In this thesis we describe advantages of diffractive solar sailing for trajectory and attitude control. In particular, a high inclination angle heliophysics mission is examined. A simple roll maneuver of a diffractive sail is described to attain an inclination angle of 60º. A comparison of idealized diffractive and reflective sails for a five-year solar polar orbiter mission, showing higher inclination angles and a smaller orbital radius for the former is performed. As a result, a constellation of diffractive solar sails for heliophysics imaging and data gathering can be envisioned. A series of 14 [kg], 400 [m2] lightsails at various inclination angles could be in place at 0.32 [AU] within six years of launch. Based on our survey of current solar sailing and attitude control systems, the feasibility of performing these maneuvers and the advantages diffractive elements can enable are explored. A theoretical model of the sailcraft is derived and various attitude control systems are numerically modeled. This analysis includes classical control devices such as reaction wheels and novel approaches with electro-optically controlled devices. It is concluded that while a fully electro-optic system is sufficient in the long term, a hybrid system of both small reaction wheels and electrically controlled diffractive elements provides an advantageous solution and could be expanded for other solar sailing applications in the near future

Science opportunities with solar sailing smallsats

Recently, we witnessed how the synergy of small satellite technology and solar sailing propulsion enables new missions. Together, small satellites with lightweight instruments and solar sails offer affordable access to deep regions of the solar system, also making it possible to realize hard-to-reach trajectories that are not constrained to the ecliptic plane. Combining these two technologies can drastically reduce travel times within the solar system, while delivering robust science. With solar sailing propulsion capable of reaching the velocities of ~5-10 AU/yr, missions using a rideshare launch may reach the Jovian system in two years, Saturn in three. The same technologies could allow reaching solar polar orbits in less than two years. Fast, cost-effective, and maneuverable sailcraft that may travel outside the ecliptic plane open new opportunities for affordable solar system exploration, with great promise for heliophysics, planetary science, and astrophysics. Such missions could be modularized to reach different destinations with different sets of instruments. Benefiting from this progress, we present the "Sundiver" concept, offering novel possibilities for the science community. We discuss some of the key technologies, the current design of the Sundiver sailcraft vehicle and innovative instruments, along with unique science opportunities that these technologies enable, especially as this exploration paradigm evolves. We formulate policy recommendations to allow national space agencies, industry, and other stakeholders to establish a strong scientific, programmatic, and commercial focus, enrich and deepen the space enterprise and broaden its advocacy base by including the Sundiver paradigm as a part of broader space exploration efforts.Comment: 34 pages, 12 figures, 2 table