Light sails for interstellar travel Author: A.R. Davoyan, Assistant Professor of Mechanical and Aerospace Engineering, University of California, Los Angeles Background: So far only two probes have left the boundaries of our solar system. It took Voyager 1 – the fastest spacecraft ever built – 40 year of flight to reach the interstellar medium. Further exploration of deep space, interstellar medium and travel to neighboring stars requires new ways of spacecraft design and propulsion. Conventional chemical and electric propulsion systems are impractical for such far-reach missions. Photon propulsion, in contrast, is not bounded by the rocket equation and provides practical means for fast deep-space exploration. Objective: In this talk we discuss of light sail design needed for future breakthrough photon propulsion missions. Specifically, we discuss two scenarios: beamed energy propulsion with high power ground based lasers and extreme solar sails making use of small perihelion approach. We consider material challenges and photonic designs that can enable such extreme light sails for future photon propulsion. Methods: In our analysis we make a comprehensive analysis of materials properties, their thermal stability an optical responses, particularly absorbance and deduce that a certain set of ceramic and high index semiconductor materials is particularly suited for high radiation power. We then discuss different photonic structures that can help minimizing the mass of the sail. Results: Our analysis suggests that ultrathin film materials for solar and laser beam sailing may designed. Specifically we show that solar sails capable of >30Au/year may be designed, as well as laser sails that can be propelled to relativistic speed. TRL: Our technology is at TRL 2. Development Roadmap: We further identify next steps needed to extend the TRL, specifically we will discuss the use of machine learning, optimization, and experimental testing. The long term goal is flight demonstration and in-space technology testing. Near-term technical milestones and performance metrics: Near term goals include laboratory stauied of materials and demonstration of their performance in extreme radiation environment. Conclusions: Our analysis shows a great promise for the design of novel photon propulsion systems for a scalable and fast space exploration and deep space travel.