A new approach to solar sail design using diffractive optics could enable spacecraft to photograph the poles of the sun for the first time. Over the next two years, Rochester Institute of Technology (RIT) professor Grover Swartzlander will explore the feasibility of diffractive solar sails for propelling spacecraft. He has received a Phase II award through NASA’s Innovative Advanced Concepts (NIAC) program to support his research. RIT professor Grover Swartzlander discussed his work on diffractive solar sails at the NASA Inventive Genius lecture series at the Chicago Museum of Science and Industry in April 2019. Courtesy of J.B. Spector/Museum of Science and Industry. Swartzlander is developing the diffractive solar sails using optical films made from metamaterials. This approach allows the sails to have a lower mass than a reflective sail made with a metal coating on a thin polymer. Instead of mechanical navigation, the diffractive solar sails will use electro-optic beam steering, which is more efficient and less prone to breakdowns. “We’re embarking on a new age of space travel that makes use of solar radiation pressure on large, thin, sail membranes,” Swartzlander said. “In comparison to a reflective sail, we think a diffractive sail could be more efficient and could withstand the heat of the sun better. These sails are transparent so they’re not going to absorb a lot of heat from the sun, and we won’t have the heat management problem as you do with a metallic surface.” Swartzlander conducted a nine-month Phase I NIAC study in 2018, which culminated in an incubator meeting in Washington, D.C., to create a roadmap for advancing metamaterial sails on cubesats. Ultimately, Swartzlander wants to use the diffractive sails to install a constellation of satellites at different orbits around the sun to provide a 360° view of it. He hopes to see a mission within the next five years that will demonstrate how the diffractive solar sails will perform in space.
