Space exploration usually brings to mind rockets burning through vast amounts of fuel to escape Earth and journey through the solar system.
But what if spacecraft could travel without carrying fuel at all? A new study from the University of Nottingham suggests that may soon be possible, thanks to a new type of solar sail that uses sunlight in a smarter way.
Solar sails are not a new idea.
For decades, scientists have imagined using large, ultra-thin sheets to catch the momentum of sunlight to propel spacecraft, much like wind pushes a sailboat. Traditional designs rely on reflecting sunlight to generate thrust.
The Nottingham team, however, is developing a new class of sails that don’t just reflect light—they bend it.
These “transmissive solar sails” are covered in microscopic refractive patterns that steer and accelerate spacecraft using light alone. Because they don’t need engines or fuel, they could enable long-duration space missions, reduce costs, and open the door to more sustainable space exploration.
The research, published in Acta Astronautica, introduces an optimization framework that helps scientists design and test these tiny patterns. By fine-tuning how the patterns bend light, the team achieved far greater efficiency and control than earlier concepts.
Ph.D. student Samuel Thompson, who led much of the technical development, explained how the team modeled the sails. “I developed a ray-tracing simulation to characterize and optimize patterned, refractive solar sails to maximize their acceleration and stability,” he said.
Because the light behavior is complex and unpredictable, Thompson also built a reinforcement learning algorithm to test thousands of possible designs and automatically improve them.
This approach means the sails could be customized for specific missions—whether to push a small satellite through low-Earth orbit or to propel a deep-space probe on a long journey. They could even be redesigned mid-development to match changing mission needs.
The Nottingham researchers believe these sails may be especially valuable for sustainable space operations. One promising use is clearing out space debris, since solar sails could move small, uncontrolled objects out of Earth orbit without requiring expensive propulsion systems.
Beyond space exploration, the work may also have planetary applications. The team has contributed to international research exploring the idea of solar sail-enabled “planetary sunshades.” These giant sails, positioned in space, could reflect or diffuse sunlight to help cool Earth’s climate as part of global geoengineering strategies.
University of Nottingham researcher Dr. Cappelletti recently presented this concept at a United Nations event on climate innovation, highlighting its potential role in future climate resilience.
Meanwhile, the NottSpace research team is already integrating transmissive sails into real-world missions. Their in-house CubeSat projects, WormSail and JamSail, will use these sails for experiments ranging from mapping GPS jamming signals to supporting pharmaceutical research in space.
By reimagining how spacecraft can harness sunlight, Nottingham’s transmissive solar sails point to a future where we can travel farther, explore longer, and even help protect our planet—all without using a drop of fuel.
