Lightsail Technology Steps into the Future

Light sails were once a thing of science fiction, evolving through several variations over the past 40 years. Today, science fiction becomes reality. Advances in laser technology and new ultra-strong, ultra-lightweight materials open up the possibility of venturing beyond our solar system in the not-too-distant future.

Researchers from UCLA and the University of Pennsylvania recently published two papers describing various heat-dissipating shapes and materials they tested to evaluate light sails beyond previous limits. The research was conducted in conjunction with the Breakthrough Starshot Initiative, a project to send a microchip-sized probe to the Alpha Centauri system, which, just over 4 light years away, is the nearest neighboring star. nearest and perhaps the most livable. system. The Starshot breakthrough plans to use a high-powered laser array to propel tiny light-sail probes through space at a top speed of about 20% the speed of light. Embedded in the sails would be tiny scientific instruments, such as cameras, magnetometers, and communicators that could send information back to Earth as they fly through the Alpha Centuari system.

A heat resistant parachute

Aaswath Raman, a professor in UCLA’s Department of Materials Science and Engineering, defined two key elements to creating a functional light sail: it must be extremely light, and it must reflect or disperse heat incredibly well.

Previously tested solar sails, which harness the momentum of photons from the Sun, only require reflective mylar or plastic with aluminum to survive. However, Raman’s research focuses on light sails that would be propelled by laser beams much more intense than the sun’s rays, and reflective light sails made of mylar or plastic would quickly disintegrate when blasted with lasers as well. powerful. Published in January, the research outlines the secret ingredients that can help these glowing veils disperse the abundant heat that builds up when they are targeted by lasers: 2H-phase molybdenum disulfide, crystalline silicon nitride, and nanometer scale. The sail’s grid-like fabric, the width of a human hair, is specially designed to resist heat by effectively harvesting laser light so that it is rapidly accelerated, reducing the need for exposure to long term laser beam

Also integral to the research was Igor Bargatin, a professor in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. Bargatin not only co-authored Raman’s paper, but also led his own study, published last December. In his work, he describes and calculates the most suitable general shapes and mechanisms for a sail of laser-powered light.

Bargartin discovered that the sail of light had to have a curvature to be able to inflate and avoid tearing. This curvature should also be significant, with the ideal light sail being about as deep as it is wide. That would make such a luminous sail more of an old-fashioned parachute than a ship’s sail.

Another consideration was to make the light sail extremely thin, but not too thin. “It goes at a much faster speed than any other spacecraft, so we had to consider that the light intensities would be large, so extremely thin. We found that balance in the light pressure that wouldn’t tear in the acceleration phase,” Bargatin said. He is currently testing some theories and creating prototypes, the results of which should be published within the next year.

Deep Jariwala, a professor in the Department of Electrical and Systems Engineering at the University of Pennsylvania, is working with others to fabricate parts for a prototype light sail. But whether or not these researchers realize the noble mission of the Starshot Initiative, Bargatin and Raman think their work could also have much closer-to-Earth applications.

“This particular project has an extreme set of constraints or requirements because the goal is so aggressive. We can do it in the next couple of decades, but anything we learn about laser-based sails could also help us to go to Neptune or Uranus, which were kind of out of reach of the solar sails,” Raman said.

Progress with Breakthrough Starshot

The Starshot initiative is still in its very early stages of development. But since the project launched in 2016, Avi Loeb — chairman of Starshot’s advisory board and professor of astronomy and cosmology at Harvard University — doesn’t think he’s encountered any breakthrough technological challenges, or what he likes to call it. “showstoppers”. .”

In fact, Loeb said development of the light sail has seen the most progress, while development of the communication aspects of the mission has been much more difficult. He explained that the transmission of information becomes much weaker over distances on the scale of light years, not to mention that it would take a little over four years for the signal to reach Earth.

Over $100 million has been allocated to the Breakthrough Starshot project for the next decade or more of research. However, Loeb thinks the investigation could take at least another two decades and likely be one of the costliest space ventures we’ve ever seen.

But for him, it’s a worthwhile investment. Not only will the technological advancements produced by the Breakthrough Starshot Project ripple through the real world here on Earth, but Loeb believes knowing what lies outside our solar system is important for future generations.

“We want to see that we’re not the smartest kids on the cosmic block,” Loeb said.

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