SmartNode is a satellite relay simulation platform for space-based data backhaul, combining a Flask REST API backend with a Vue 3 frontend that visualizes satellite constellations on a Cesium 3D globe. It simulates LEO/MEO/GEO satellites, ground stations, and relay links, processing data transmission requests with configurable QoS, security, and value profiles. The backend implements orbital propagation (SGP4/TLE, Keplerian elements), ITU-R link budget models (rain attenuation, gaseous absorption, laser ISL), and scheduling strategies (GreedyMaxRate, QoS-aware admission control, handover with hysteresis). Results are persisted in SQLite and an append-only event log, with real-time updates pushed via SSE. The platform includes a full observability stack (Prometheus, Grafana, OpenTelemetry), containerized deployment, and extensive testing (unit, integration, property-based, golden regression, load). While primarily an application, it incorporates significant data/research components in orbital mechanics, communications, and scheduling algorithms, making it a hybrid but application-dominant project.