Delft and Brown researchers unveil ultrathin sails for laser propulsion in space

Delft and Brown researchers unveil ultrathin sails for laser propulsion in space
by Robert Schreiber
Berlin, Germany (SPX) Mar 25, 2025

Researchers from Delft University of Technology and Brown University have introduced a breakthrough in nanotechnology with the development of large-scale, ultrathin lightsails, poised to accelerate advances in both space travel and experimental physics. Published in Nature Communications, their work outlines novel materials and techniques that yield the thinnest extensive reflectors ever fabricated.

Lightsails function as ultra-light, mirror-like membranes that harness the force of laser-driven radiation pressure to propel spacecraft at remarkable speeds. Distinct from conventional nanotech, which scales down devices in every dimension, these sails remain at nanoscale thickness but can expand to vast areas.

Previously, constructing lightsails akin to those envisioned by the Starshot Breakthrough Initiative could require up to 15 years, due to the need for billions of nanoscale perforations. However, leveraging innovative methods, the research team, led by PhD candidate Lucas Norder, has condensed this timeline to just 24 hours.

Redefining nanotechnology's scope

"This is not just another step in making things smaller; it's an entirely new way of thinking about nanotechnology," explains Dr. Richard Norte, associate professor at TU Delft. "We're creating high-aspect-ratio devices that are thinner than anything previously engineered but span dimensions akin to massive structures." Their prototype, measuring 60mm by 60mm and only 200 nanometers thick, integrates billions of nanoscale holes and marks a significant milestone in scalable lightsail production.

Dr. Norte highlights the contrast with recent progress from other institutions, such as Caltech, which achieved nanoscale control at micrometer dimensions. In comparison, their technology supports centimeter-scale precision while preserving nanoscale features. A full-scale version could stretch the length of seven football fields yet remain a mere millimeter thick. "It's not just its high aspect ratio that makes this material special; it's the simultaneous combination of large scale and nanoscale in the same material that makes it lightweight and reflective," says Norte.

The team employed a fusion of advanced neural topology optimization and state-of-the-art fabrication methods. "We have developed a new gas-based etch that allows us to delicately remove the material under the sails, leaving only the sail," Norte explains. "If the sails break, it's most likely during manufacturing. Once the sails are suspended, they are actually quite robust. These techniques have been uniquely developed at TU Delft."

"Our work combines the latest advancements in optimisation to explore new ways to find unintuitive designs," says Dr. Miguel Bessa from Brown University. "By blending neural networks with topology optimization, we've created designs that push the boundaries of what's possible in both nanophotonics and large-scale manufacturing."

From minuscule scales to cosmic distances

The lightsails utilize radiation pressure from lasers to reach exceptional velocities, potentially enabling swift interplanetary missions. Space probes using this technology could theoretically reach Mars in the same time a letter takes to cross continents. While interstellar travel remains a future goal, current prototypes have already demonstrated propulsion over picometer distances. The Delft team now aims to achieve movement over centimeter distances on Earth, defying gravity. "It might not sound like a lot, but this would be 10 billion times farther than anything pushed with lasers so far," Norte notes.

Beyond propulsion, the materials also present new opportunities for exploring light-matter interactions and relativistic phenomena at macroscopic scales. Norte emphasizes, "This EU-funded research places Delft at the forefront of nanoscale material science. Now that we can make these lightsails as large as semiconductors can make wafers, we are exploring what we can do with today's capabilities in nanofabrication, lasers, and design. In some ways, I think it might be just as exciting as missions beyond the solar system. What is remarkable to me is that creating these thin optical materials can open a window into fundamental questions such as; how fast can we actually accelerate an object. The nanotechnology behind this question is certain to open new avenues of interesting research."

Breakthrough Starshot Initiative

Current spacecraft would need about 10,000 years to reach the nearest star. The Breakthrough Starshot Initiative, a global collaboration launched by Yuri Milner and Stephen Hawking in 2016, seeks to shorten this to 20 years using ultra-light, laser-driven microchip-sized spacecraft. It is part of the privately funded Breakthrough Initiatives.

Research Report:Pentagonal photonic crystal mirrors: scalable lightsails with enhanced acceleration via neural topology optimization