orts is an astrodynamics simulation platform — orbit and attitude dynamics with real-time 3D visualization, extensible WASM plugins, and in-browser analytics.

• N-body orbital simulation with adaptive (DOP853, Dormand-Prince) and symplectic (Störmer-Verlet, Yoshida) integrators
• Gravity models: point-mass, zonal harmonics (J2, J3, J4)
• Perturbations: atmospheric drag, solar radiation pressure, third-body gravity, constant thrust
• Atmosphere models: Exponential, Harris-Priester, NRLMSISE-00
• Geomagnetic field: IGRF-14 spherical harmonic expansion + tilted-dipole approximation
• Space weather: CSSI and GFZ providers (F10.7, Ap, Kp)
• IAU 2006/2000A CIO-based Earth rotation with typed coordinate frames and EOP
• Celestial body ephemerides (Meeus analytic + JPL Horizons)
• Attitude dynamics and control: reaction wheels, magnetorquers, B-dot / PD controllers
• Sensor models: magnetometer, gyroscope, sun sensor, star tracker (with noise)
• WASM Component Model plugin runtime for guest controllers via wasmtime
• CLI with embedded 3D viewer, WebSocket telemetry, and format conversion
• Real-time charting with DuckDB-wasm + uPlot (uneri library)
• Rerun .rrd data format for recording and replay

# From source
cargo install orts-cli

# Pre-built binary (cargo-binstall)
cargo binstall orts-cli

# Run a simulation (auto-detects orts.toml in current directory)
orts run

# WebSocket server with embedded 3D viewer
orts serve --config orts.toml
# Open http://localhost:9001

# Replay a recorded simulation
orts replay output.rrd

# Convert between formats
orts convert output.rrd --format csv

Example config (orts.toml):

body = "earth"
dt = 0.01
duration = 120.0

[[satellites]]
id = "sat-1"
sensors = ["gyroscope", "star_tracker"]

[satellites.orbit]
type = "circular"
altitude = 400

[satellites.attitude]
inertia_diag = [10, 10, 10]
mass = 500

[satellites.reaction_wheels]
type = "three_axis"
inertia = 0.01
max_torque = 0.5

Write satellite attitude controllers in any language that compiles to WebAssembly. Plugins receive sensor readings (magnetometer, gyroscope, star tracker, etc.) each tick and return actuator commands (reaction wheels, magnetorquers) — the simulator handles all dynamics and environment models.

# Install cargo-component
cargo install cargo-component

# Build an example plugin
cd plugin-sdk/examples/pd-rw-control
cargo component build --release

Add a plugin controller to your config:

[satellites.controller]
type = "wasm"
path = "target/wasm32-wasip1/release/orts_example_plugin_pd_rw_control.wasm"

[satellites.controller.config]
kp = 1.0
kd = 2.0
sample_period = 0.1

See plugin-sdk/examples/ for more plugin examples, and examples/ for Apollo 11, Artemis 1, and orbital lifetime analysis demos.

• Docs site — API reference, examples, guides
• ARCHITECTURE.md / 日本語 — Top-level architecture overview
• DESIGN.md — Design document (Japanese)
• CHANGELOG.md — English changelog
• CHANGELOG.ja.md — Japanese changelog
• RELEASING.md — Release process

MIT