We are excited to share the code for Mega-Constellation Digital Twin — a research-grade 3D simulator for LEO mega-constellations and laser inter-satellite links (LISL).

This effort began with a simple question: how to calculate the capacity of a LEO mega-constellation with LISL connectivity. Joint connectivity and routing optimization at sub-second timescales is essential for dynamic network topologies, yet existing open-source tools were unable to evaluate thousands of links efficiently, so we developed our own.

This Mega-Constellation Digital Twin is designed to enable experimentation and visualization of real-time, LISL-connected constellation dynamics at scale (Starlink-size). It provides a practical platform for initiating research on satellite network resource and topology optimization for mega-constellations.

The simulator is already accelerating our research on large-scale LEO satellite LISL optimization, and was selected for feature in Quantum Zeitgeist: “Optimised LISL Routing Achieves Maximum Throughput for LEO Mega-Constellations.” We look forward to its broader impact on the community and its role in addressing emerging challenges in beyond-5G NTNs.

This project was developed at FCCLab@SUTD under the supervision of Prof. Jihong Park, with Dr. Zhouyou Gu (FCCLab Research Fellow) leading the simulator development and applications.

For more details, please refer to below links:
-Repo: https://github.com/zhouyou-gu/mega-constellation-demo;
-Paper: https://arxiv.org/abs/2601.21921; https://arxiv.org/abs/2601.21914;