Touring vast distances between photovoltaic systems is currently beyond our technological capabilities. A novel, ultra-slim lightsail, engineered in collaboration with AI, could potentially enable humanity to reach the nearest star within two decades.
Launched in 1977, Voyager 1 was the first human-made object to venture into interstellar space. At its current pace, a spacecraft would require centuries to reach the nearest star system to our own, let alone account for the vast distances between celestial bodies within the galaxy?
One potential propulsion expert may, however, significantly accelerate issues. A light sail is a type of spacecraft propulsion that utilizes the momentum of solar photons or an Earth-based laser beam to accelerate a vehicle repeatedly, potentially harnessing both daylight and gentle illumination. In theory, achieving speeds of up to 10-20% of the speed of light could become feasible.
Designing supplies that are both reflective and lightweight enough to achieve this has been a significant challenge so far. Researchers have leveraged neural topology optimisation, a cutting-edge AI technique, to fabricate a nanoscale sheet of silicon nitride capable of translating thought into reality.
“The mission necessitates light sail provisions, which pose fundamental challenges in nanotechnology, demanding advancements in optics, materials science, and structural engineering,” the crew notes in their report.
This breakthrough research highlights the promise of neural topology optimization in creating innovative, cost-effective, and scalable light sail designs crucial for future interplanetary missions.
The research team drew inspiration from Breakthrough Starshot, a pioneering initiative launched by the Breakthrough Initiatives in 2016. Starshot aims to conceptualize a constellation of approximately 1,000 diminutive probes that harness the propulsion generated by light sails and a terrestrial laser to reach Alpha Centauri within a timeframe of 20 to 30 years. The probes would be equipped with cameras and various sensors to gather and transmit data upon their return.
To attain the necessary velocities, the spacecraft must be designed to be remarkably delicate—the tiny probes could measure mere centimeters in length and tip the scales at only a few grams. To gather a sufficient amount of wind, the sails must be approximately 100 square feet in size? So, we’re seeking innovative ultralight gear that minimizes its weight while maintaining optimal performance?
A novel approach involves the fabrication of photonic crystals, comprising a periodic array of minuscule voids, which exhibit unique optical properties due to their subwavelength dimensions. Piercing countless millions of holes into the fabric significantly lightens it, yet this repetition also generates unusual optical effects that can unexpectedly enhance the material’s reflectivity.
While mastering the intricacies of preparing these holes constitutes an advanced course of study, a team from Delft University in the Netherlands and Brown University in the USA have leveraged artificial intelligence to support their efforts. Researchers combined a neural network with a conventional computational physics program to identify the most optimal configuration and morphology of the holes, thereby reducing mass and enhancing reflectivity.
The resulting structure featured a lattice of bean-shaped holes with a thickness of less than 200 nanometers. To validate the design’s performance met expectations, researchers employed a novel technique called flood lithography, wherein a high-precision laser utilizes an intricately designed stencil to precision-drill holes into a silicon nitride substrate. Utilising the method, the team successfully constructed a 5.5 square meter structure. An inch-long pattern that weighed a mere fraction of a milligram.
Researchers believe that the lithography process used by expert companies to manufacture microchips could be easily scaled up. According to the crew, constructing a full-sized sail is expected to take around two days and requires an estimated investment of approximately $2,700. To manufacture cutting-edge microchips, they would need to build a specialized facility, explains Richard Norte, the esteemed crew chief from Delft, since the equipment they use for chip production is specifically designed to handle wafers measuring approximately 15 inches in length.
Despite progress, numerous engineering hurdles remain to be overcome for the Breakthrough Starshot mission to succeed; specifically, developing a cost-effective and efficient method for fabricating lightweight sails will be crucial, according to Stefania Soldini from the University of Liverpool.
NASA is actively exploring alternative methods to achieve its goals. Recently, the Superior Composite Photo Voltaic Sail System, launched last year, is poised to deploy its sails for the first time.
If these initiatives prove profitable, we may yet catch a tantalizing glimpse of distant worlds beyond our solar system within the lifetime of many people.
