12-03, 11:20–11:40 (Europe/Luxembourg), Banquet Room
Solar sail missions hold considerable promise for expeditions to the outer reaches of the solar system and interstellar travel due to their propellantless character. One approach to achieving high velocities involves utilizing a solar flyby (gravity and photonic assist) to accelerate the sail away from the solar system.
Recent attention has focused on aerographene, an ultra-lightweight material with a density of 0.16 kg/m3, offering significantly improved performance potential compared to conventional ma- terials like mylar or kapton. However, aerographene’s complete absorptive nature poses challenges for controllability of the sail, e.g. the ability to arbitrarily change its trajectory.
In this study, we propose an optimal control approach to find a trajectory maximizing the excess velocity of a solar sail towards the farthest regions of the solar system, leveraging a solar flyby. We address the challenge of temperature constraints, crucial for preventing material degradation near the Sun. This involves incorporating constraints on both the state variable (distance from the Sun) and control variable (orientation of the sail) to manage surface temperature fluctuations. Specifically, while proximity to the Sun may be necessary for gravitational and photonic assists, it also risks excessive heating, necessitating adjustments to sail orientation to mitigate temperature effects.
To solve this optimal control problem with combined constraints, we employ a multiple shooting method with a constrained arc. We derive optimality conditions using Pontryagin’s principle and analyse the Hamiltonian dynamics to formulate an optimal control problem tailored to ideal, i.e. perfectly reflective, solar sails.
Furthermore, continuation techniques are employed to assess the impact of degraded sail perfor- mance (with a less reflectivity coefficient) on trajectory variations. This exploration aims to determine the feasibility of interstellar missions solely with aerographene sails.
This comprehensive study offers insights into optimizing solar sail trajectories, addressing key challenges for ambitious deep space exploration missions. By integrating theoretical analysis, nu- merical simulations, and innovative design concepts, we advance our understanding of solar sail dynamics, laying the groundwork for future interstellar exploration endeavours.
Dr. Alesia Herasimenka's field of research is space mission design, which involves trajectory optimisation, control of spacecrafts, and aerospace engineering. Dr. Alesia Herasimenka is Research Associate in the SpaceSystems team at the Interdisciplinary Centre for Security, Reliability, and Trust (SnT) at the University of Luxembourg. She received a PhD in Mathematics within McTAO, a common team between Laboratory J. A. Dieudonné at Université Côte d’Azur and Inria Sophia Antipolis. Her PhD thesis was about optimal control of solar sail and was co-funded by ESA.
Andreas Hein is an associate professor of space systems engineering at the University of Luxembourg’s Interdisciplinary Center for Security, Reliability, and Trust (SnT). He works on space systems that are miniaturized and distributed, including ChipSats and CubeSats, operated in swarms and formations, in-space manufacturing, and in-situ resource utilization.
Andreas is also the Executive Director and Director Technical Programs of the UK-based not-for-profit Initiative for Interstellar Studies (i4is), where he is coordinating and contributing to research on diverse topics such as missions to interstellar objects, laser sail probes, self-replicating spacecraft, and world ships. He obtained his Bachelor’s and Master’s degree in aerospace engineering from the Technical University of Munich and conducted his PhD research on space systems engineering there and at MIT. He has published over 70 articles in peer-reviewed international journals and conferences.