Lightsails are ultra-thin (about 1/1000th the width of a human hair,) large scale reflective structures that use radiation pressure from lasers for spacecraft propulsion. The Breakthrough Starshot Initiative announced their plans to fund research back in 2016 and aims to use the sails to send miniature spacecraft to Alpha Centauri, our nearest star system. They hope to be able to accelerate the tiny probes to 20% of the speed of light using powerful ground based lasers so that they reach their destination in around 20 years! Constructing lightsails was once a complex 15-year process but, thanks to their funding, this has been streamlined to just one day.
Artist Impression of a lightsail (Credit : Kevin Gill from Nashua, NH, United States)
The progress is thanks to research teams like those from TU Delft and Brown University that have developed nanotechnology based lightsails. Their approach creates extremely thin reflectors and whilst they believe they can go large, their current prototype measures just 60mm x 60mm and is just 200 nanometers thick. The team are confident the technology can be scaled up to produce sails that could cover seven football fields yet still be lightweight.
‘Other recent advancements in the field, such as from Caltech, have demonstrated nanoscale control over sail structures at micrometer scales, whereas our approach scales to centimetre sized structures while maintaining nanoscale precision manufacturing.’ – Dr. Richard Norte, associate professor at TU Delft
The team’s approach combines neural topology optimisation to identify optimal design and material distribution along with advanced fabrication techniques. They were able to develop a specialised gas based etching method that delicately removes material from beneath the lightsails reducing their overall mass. By using neural networks with topology optimisation, the team were able to create a new design that makes the possibility of large scale manufacturing a reality.
The newly developed lightsails use pressure from lasers to accelerate to substantial proportions of the speed of light, with the ambitious goal of significantly reducing travel times. Currently a trip to Mars can take up to 9 months but they muse they hope to find a way to get to Mars as quickly as international mail is delivered! While current experiments are little more modest with lightsails being pushed across tiny distances, the team are hoping to propel their prototypes across centimetre scale distances, a leap that represents a 10 billion-fold improvement over previous laser propulsion studies.
There is no doubt, and this recent announcement by Norte’s team confirm that lightsail research could dramatically and positively impact the exploration of space. Dr. Norte emphasises that developments in nanofabrication, laser technology, and design techniques are not just going to benefit interstellar missions, but also help answer scientific questions about the limits of object acceleration, potentially opening entirely new avenues of scientific investigation that could be just as exciting as space exploration itself!
Source : Delft University of Technology and Brown University pioneer technology for next-generation lightsails in space exploration