Conjunction Detector

Satellite conjunction detection system that monitors orbital objects for potential collisions. Ingests data from
Space-Track.org, propagates orbits using Orekit, and identifies close approaches
between satellites.

Tech Stack

• Java 25
• Spring Boot 4 / Spring Modulith
• Orekit 13
• PostgreSQL / Flyway
• HTMX / Thymeleaf

Architecture

The application is organized into five modules:

• Ui - UI controllers and scheduled jobs
• Conjunction - Detection algorithms and conjunction storage
• Ingestion - Orchestrates catalog synchronization from Space-Track
• Satellite - Satellite entity and repository
• Spacetrack - HTTP client for Space-Track.org API

Coarse and Fine Scanning

The detection algorithm uses a two-step approach:

1. Coarse sweep: Pre-computes satellite positions using SGP4 with Hermite interpolation, then uses spatial grid
   indexing to efficiently find nearby satellites within tolerance
2. Refinement: Solves for precise TCA and miss distance, filtering by 5 km collision
   threshold

See docs for tuning experiments and optimal parameters.

Setup

Prerequisites

• Java 25
• Docker Compose
• Space-Track.org account

1. Configure Environment

Copy the example environment file and fill in your Space-Track credentials:

cp .env.example .env

2A. Run with Docker Compose

docker compose up

This starts PostgreSQL and the application. The app will be available at http://localhost:8080.

2B. Running Locally for Development

docker compose up postgres -d
./mvnw spring-boot:run