v1.2.3 - Release: Unified Core API, Physical Invariant Verification & Open-Source Licensing

Overview

Major milestone release introducing official MIT open-source licensing, formal academic metadata alignment (CITATION.cff), unified SpacecraftPropagator core execution interfaces, a 35-test physical-invariant validation suite, and automated Material for MkDocs API documentation.

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Key Features & Scenarios

• Official MIT Open-Source Licensing: Added the root LICENSE file under the MIT License, clarifying distribution, academic reuse, and copyright protection across external research institutions and contributors.
• Unified Propagator Interface: Harmonized the SpacecraftPropagator architecture across classical Runge-Kutta 4 (RK4) and adaptive Dormand-Prince (RK45) numerical integrators, streamlining 6-DOF and 7-DOF propagation pipelines.
• Superposition Force Expansion: Substantially extended perturbation modeling in core/forces.py (+312 lines), incorporating high-order geopotential zonal harmonics ($J_2$ - $J_4$), atmospheric drag, and Solar Radiation Pressure (SRP).
• Material for MkDocs API Reference: Deployed a complete Material for MkDocs technical documentation platform with automated API reference generation (docs/gen_ref_nav.py), MathJax LaTeX rendering, and automated GitHub Pages deployment pipelines (.github/workflows/docs.yml).
• Packaging & Metadata Modernization: Synchronized project configurations in pyproject.toml (PEP 517/621), CITATION.cff, and mkdocs.yml with updated author credentials, release versioning, and modular dependency groups (docs, test, dev).

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Verification

• Physics-Grounded Test Suite: Established an extensive 35-test verification suite in tests/ asserting symplectic invariant preservation, two-body mechanical energy conservation, and Jacobi constant stability in CR3BP systems.
• Boundary Condition Targeting Checks: Verified universal variable Lambert solver targeting, hyperbolic flyby turning angles, and asymptotic $\Delta v$ conservation across planetary flybys.
• Relative Swarm Dynamics: Validated multi-agent constellation relative motion in the Local-Vertical Local-Horizontal (LVLH) frame against analytical Clohessy-Wiltshire formulations.
• Automated CI/CD Workflows: Confirmed all continuous integration pipelines across .github/workflows/ (tests.yml, docs.yml, and update-citation.yml) pass cleanly across Python versions 3.10 through 3.12.

v1.1.5 - Release: Theoretical Foundations, Literature Guide & Documentation Architecture

Overview

Documentation and academic milestone release introducing a dedicated reference guide (REFERENCES.md), establishing formal astrodynamics literature citations, and streamlining repository-wide navigation and cross-linking.

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Key Features & Scenarios

• Dedicated Astrodynamics Reference Guide: Integrated REFERENCES.md covering primary literature (Bate, Curtis, Vallado, Szebehely) underpinning core Keplerian propagation, Lambert targeting, perturbation mechanics, and three-body dynamics.
• Theory & Implementation Endnotes: Added formal mathematical context mapping code routines to established astrodynamic theory, including CR3BP rotating-frame formulations (core/cr3bp.py), universal variable Lambert mechanics (core/lambert.py), and non-spherical gravitational harmonics (core/forces.py).
• Curated Further Reading: Structured literature pathways for advanced mission design topics, spanning low-thrust electric spiral transfers, multi-agent LVLH formation flying, interplanetary gravity-assist scattering, and geometric/symplectic numerical integrators.
• Streamlined Documentation Navigation: Upgraded README.md with an instant-access top navigation header linking the Quickstart Guide, References, Interactive Notebooks, and Architecture.
• Getting Started Directory Integration: Added an explicit Documentation & Getting Started section to README.md alongside an updated ASCII repository architecture tree incorporating REFERENCES.md.

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Verification

• Cross-Link & Markdown Validation: Verified clean relative-link resolution across README.md, QUICKSTART.md, REFERENCES.md, and the interactive notebooks in notebooks/.
• LaTeX Formula Rendering: Validated standard Markdown and LaTeX math blocks across all updated documentation files for consistent GitHub web viewer rendering.
• Dynamic Versioning Consistency: Verified package version resolution via setuptools-scm to ensure metadata synchronization across environments and releases.
• Test Suite & CI Continuity: Confirmed existing automated test matrix suites across tests/ remain fully passing without regressions across supported Python environments (.github/workflows/tests.yml).

v1.0.0 - Release: Core Astrodynamics & Adaptive Solvers

Overview

Major milestone release introducing high-performance adaptive numerical integration with local truncation error control, complete Circular Restricted Three-Body Problem (CR3BP) dynamics, and validation benchmarks.

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Key Features & Scenarios

• Adaptive Dormand-Prince Integrator: Implemented embedded RK5(4) solver with local truncation error (LTE) step-size scaling and First Same As Last (FSAL) efficiency (core/integrators.py).
• CR3BP Cislunar Dynamics & Equilibria: Non-dimensional rotating-frame equations of motion with root-finding solvers for $L_1\text{-}L_5$ Lagrange points and continuous Jacobi constant ($C_J$) tracking (core/cr3bp.py).
• Scenario 6 Free-Return Upgrade: Benchmarked Earth-Moon figure-8 free-return trajectory comparing classical RK4 against adaptive RK45 in both synodic and inertial frames (examples/ex06_cislunar_free_return.py).
• Scenario 7 Earth–Mars Transfer Optimization: Integrated RK45 propagation into the porkchop-derived Lambert transfer arc, reducing deep-space cruise evaluations by >99% (examples/ex07_earth_mars_transfer.py).
• Scenario 8 Multi-Leg Flyby Dynamics: Patched-conic Earth–Venus–Mars (EVM) gravity-assist trajectory verification updated with dual-leg RK4 vs. RK45 telemetry (examples/ex08_gravity_assist_transfer.py).

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Verification

• Full Test Suite Coverage (25/25 Passing): Added tests/test_cr3bp.py and tests/test_forces.py to validate equilibrium acceleration zeroing, analytical triangular geometry, Jacobi conservation, and individual perturbation forces.
• Extreme Orbit Energy Conservation: Verified specific mechanical energy preservation on a high-eccentricity GTO ($e = 0.7265$) yielding a relative energy drift of $\Delta \mathcal{E}/\mathcal{E}_0 = 8.14 \times 10^{-10}$.
• Empirical Speedup Telemetry: Demonstrated runtime speedups ranging from $19.3\times$ to $79.4\times$ across interplanetary cruise and cislunar free-return arcs while maintaining $0.00\text{ km}$ arrival miss distances.
• Continuous Integration: Verified automated test matrices passing across Python 3.10, 3.11, and 3.12 on both Ubuntu and Windows runners (tests.yml).

v0.9.0 - Launch Vehicle Performance Sizing & Extended Ephemerides

Overview

Major feature release expanding the interplanetary trajectory suite with real-world launch vehicle performance curves, full Solar System ephemeris models, and reusable mission templates.

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Key Features & Scenarios

• Launch Vehicle Injection Sizing: Characteristic energy ($C_3$) to payload capacity models for Falcon 9, Falcon Heavy, Atlas V 551, Vulcan Centaur (VC6), and SLS Block 1 (core/launchers.py).
• Complete Solar System Ephemerides: Expanded Standish / JPL secular variation models spanning 1800–2050 to include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto (core/ephemeris.py).
• Interplanetary Mission Sandbox: Added ready-to-run Lambert transfer and launch sizing experiment template (customscripts/template_interplanetary_mission.py).
• Interactive CLI Discovery: Built-in programmatic inspection tools to query available launch vehicles and payload curves (list_available_launchers()).

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Verification

• Added dedicated test suite tests/test_launchers.py validating $C_3$ payload interpolation, vehicle bounds, and mass monotonicity across all supported configurations.
• Verified continuous integration test suite passing via GitHub Actions workflow (tests.yml).

v0.8.0 - Orbital Dynamics & Interplanetary Mission Design Engine

Overview

Initial milestone release of the NewtonianPropagator orbital mechanics and trajectory design suite. This release provides numerical propagation tools ranging from perturbed low-Earth orbits to multi-leg interplanetary flyby trajectories.

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Key Features & Scenarios

• High-Fidelity LEO Propagation: RK4 numerical integrator supporting Earth $J_2$ oblateness, atmospheric drag (exponential density model), and solar radiation pressure (SRP).
• Low-Thrust Trajectory Dynamics: Edelbaum analytical velocity estimators and continuous tangent low-thrust spiral propagators.
• Formation Flying & Swarm Dynamics: Clohessy-Wiltshire (HCW) linearized equations of motion for multi-agent spacecraft relative motion.
• Cislunar Dynamics (CR3BP): Circular Restricted Three-Body Problem equations of motion, Jacobi constant conservation tracking, analytical $L_1$ - $L_5$ Lagrange point solvers, and Apollo-style free-return trajectory modeling.
• Interplanetary Trajectory Design:
  • Lambert boundary-value problem solver (Universal Variables).
  • Earth–Mars launch window porkchop plot generator.
  • Multi-leg patched-conic gravity assist optimizer (e.g., Earth–Venus–Mars transfer).

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Verification

• Full unit test suite covering integrators, coordinate frames, Lambert solvers, and gravity assist turn angles (tests/test_*.py).