A satellite orbit visualization and conjunction analysis tool. Select two satellites to visualize their orbits in 3D and find close approaches between them.

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• Interactive 3D Earth with realistic lighting and day/night terminator
• Real-time satellite position display with orbit tracks
• Camera controls for rotation, zoom, and pan
• Toggle grid, terminator, anti-solar point, and sun line overlays

• Automatic detection of close approaches between satellite pairs
• Searches ±3 days from anchor time with 30-second resolution
• Ternary search refinement to 100ms precision for exact closest approach times
• Displays distance, relative velocity, phase angle, and Earth relation for each conjunction

• Interactive graph showing inter-satellite distance over the search window
• Click anywhere to jump to that time
• Hover for precise time and distance values
• Expand to fullscreen for detailed analysis

The fullscreen graph provides:

• High-resolution sampling (~17,000 points over 6 days)
• Mouse wheel zoom (1x to 50x)
• Click-and-drag panning
• Conjunction points marked with red circles
• Current time (blue) and anchor time (yellow) markers

• 3D visualization of Satellite B as seen from Satellite A
• North-up orientation with celestial reference
• Field of view presets: 0.5′, 3′, 20′, 120′, or auto-fit
• Sun direction indicator and velocity vector display
• Relative orbit track projection

• Side-by-side comparison of both satellites' orbital elements
• Displays: altitude, inclination, eccentricity, RAAN, argument of perigee, mean anomaly, apogee, perigee
• Current lat/long position for each satellite
• Real-time distance and relative velocity

• Built-in scenarios with interesting satellite pairs
• Embedded TLE history for offline analysis
• One-click loading of anchor time and satellite selection

• Automatic TLE fetching from Celestrak
• Intelligent epoch selection (uses TLE closest to target time)
• Local caching with 24-hour TTL
• Paste custom TLEs for any satellite

• React + TypeScript - UI framework
• Three.js via @react-three/fiber - 3D rendering
• D3.js - Interactive charting for fullscreen distance graph
• satellite.js - SGP4/SDP4 orbit propagation
• Tailwind CSS - Styling
• Vite - Build tooling

• Node.js 18+
• npm

# Clone the repository
git clone https://github.com/your-username/sattosat.git
cd sattosat

# Install dependencies
npm install

# Start development server
npm run dev

The app will be available at http://localhost:5173.

npm run build

• UI Guide - Detailed instructions for the web interface
• Scripts Guide - Command-line analysis tools documentation

1. Select Satellites: Use the dropdown menus or search to select Satellite A and Satellite B
2. Set Anchor Time: The anchor time centers the ±3 day conjunction search window
3. View Conjunctions: Close approaches are automatically calculated and listed
4. Explore Timeline: Click the distance graph to jump to any time, or expand for detailed zoom/pan analysis
5. Analyze Geometry: Use the A → B relative view to understand the visual geometry of approaches

npm run dev      # Start dev server with hot reload
npm run build    # TypeScript check + production build
npm run lint     # ESLint with zero-warnings enforcement
npm test         # Run vitest tests

The repository includes Python and TypeScript scripts for conjunction analysis and verification. See USAGE_SCRIPTS.md for complete documentation.

Quick examples (all run from project root):

# Find conjunctions using a profile
uv run python python/conjunctions.py --profile WV3-STARLINK35956-Picture

# Run envelope period analysis
uv run python python/envelope_analysis.py

# Verify Python vs TypeScript algorithm equivalence (within 27 meters)
uv run python scripts/compare-conjunctions.py --verbose

Script categories:

• Conjunction Analysis - Find close approaches between satellites
• Envelope Period Analysis - Study the rhythm of imaging opportunities
• Investigation Scripts - Starlink-35956 discrepancy analysis
• Algorithm Verification - Cross-validate Python and TypeScript implementations

• Satellite catalog and TLEs from Celestrak
• Earth textures from NASA Blue Marble

MIT