Diffractive Solar Sail Project Gets Green Light at NASA

NASA has selected a solar sail concept for development toward a demonstration mission with potential to advance space travel beyond what is currently possible.

The Diffractive Solar Sailing project was selected for Phase III study under the NASA Innovative Advanced Concepts (NIAC) program. Phase III aims to strategically transition NIAC concepts with the highest potential impact for NASA, other government agencies, and commercial partners.

Diffractive solar sails, depicted in this illustration, could enable missions to hard-to-reach places, like orbits over the sun’s poles. Courtesy of MacKenzi Martin.

“As we venture farther out into the cosmos than ever before, we’ll need innovative, cutting-edge technologies to drive our missions,” said NASA Administrator Bill Nelson. “The NASA Innovative Advanced Concepts program helps to unlock visionary ideas — like novel solar sails — and bring them closer to reality.”

Just as sailboats use wind to cross the ocean, solar sails use the pressure exerted by starlight to propel a craft through space. Existing reflective solar sail designs are typically large, thin, and limited by the direction of the sunlight — forcing trade-offs between power and navigation.

Diffractive light sails would use small gratings embedded in thin films to take advantage of the diffractive property of light, which causes light to spread out when it passes through a narrow opening. This would allow the spacecraft to make more efficient use of sunlight without sacrificing maneuverability.

The newly announced Phase III award will give the research team $2 million over two years to continue technology development in preparation for a potential future demonstration mission. The project is led by Amber Dubill of the Johns Hopkins University Applied Physics Laboratory.

The feasibility of the concept was previously studied under NIAC’s Phase I and Phase II awards, under which the team designed, created, and tested different types of diffractive sail materials, conducted experiments, and designed new navigation and control schemes for a potential diffractive light sail mission orbiting the sun’s poles.

Orbits passing over the sun’s north and south poles are difficult to achieve using conventional spacecraft propulsion. Work under Phase III will optimize the sail material and perform ground tests in support of this conceptual solar mission. Lightweight diffractive light sails, propelled by the constant pressure of sunlight, could place a constellation of science spacecraft in orbit around the sun’s poles to advance understanding of the sun and improve space weather forecasting capabilities.

“Diffractive solar sailing is a modern take on the decades-old vision of light sails. While this technology can improve a multitude of mission architectures, it is poised to highly impact the heliophysics community’s need for unique solar observation capabilities,” Dubill said.