Development Of A Laboratory Facility For Simulating Light Curves

The growing amount of Earth-orbiting space debris poses a critical challenge to the safety and sustainability of space activities. Monitoring and characterizing these objects is essential to preventing collisions and mitigating risks for operational satellites and future missions. In particular, the attitude determination of non-cooperative objects is crucial for Space Traffic Management (STM) and Active Debris Removal (ADR) operations. However, current techniques have limitations both in terms of accuracy and reliability, highlighting the need for advanced methodologies to improve the identification and characterization of these objects. The Benchmarking and Inversion of Light Curve for Attitude Reconstruction (BILAR) project aims to enhance the attitude determination of Resident Space Objects (RSOs) through advanced light curve analysis. By integrating simulations, laboratory measurements, and real-world observations, the project seeks to develop a robust and comprehensive framework for light curve-based attitude estimation. A key objective is the definition of a dedicated light curve service that addresses both industrial and academic requirements. This involves analyzing existing literature, assessing current capabilities, and identifying stakeholder needs to establish a concept of operations. The project also focuses on designing a structured light curve database, which will serve for validating attitude determination methodologies. To ensure its effectiveness, the approach includes a thorough review of existing techniques, such as the epoch method, amplitude method, and light curve fitting, followed by the implementation of integration and management procedures to facilitate database access, usage, and maintenance. The validation process will rely on ESA Expert Centre evaluations and computer simulations to validate the resulting data products. BILAR will also contribute to the growth of the ESA Expert Centre for space debris characterization, with a specific focus on sub-catalogue objects and cislunar domain observation. Additionally, the project will explore the potential of multi-wavelength photometric analysis to refine light curve inversion techniques. By incorporating spectral data, this approach aims to enhance the accuracy of attitude estimation, providing improved insights into surface properties and rotational dynamics. Within this framework, Sapienza University of Rome plays a crucial role in the design and development of the laboratory facility for simulating light curve. In particular, the Sapienza Space System and Space Surveillance Laboratory (S5Lab) contributes through the Facility for Light curve Analysis through Robotic arm and Experimental Sun simulator (FLARES). The results of the laboratory facility design will be presented, demonstrating the effectiveness of this integrated approach in improving light curve prediction accuracy. FLARES enables the simulation of satellite passages and the measurement of Bidirectional Reflectance Distribution Function (BRDF) on both scaled satellite models and material samples, providing valuable data for the validation of attitude determination methodologies. The presented approach aims to improve the accuracy and reliability of light curve simulations by integrating laboratory experimentation with digital twin simulations. The light curve facility will recreate different orbital and illumination conditions in a controlled environment, allowing for automated assessments of brightness variations at both satellite and component levels, minimizing human interaction. Finally, the Digital Twin Simulation Environment will generate synthetic light curves based on detailed spacecraft models and laboratory measurements, integrating BRDF tools to account for both specular and diffuse reflections, evaluating also existing rendering engines, such as those used in Blender and Unity, to further refine light curve simulations.