SSAPy Toolkit (Python package: ssapy_toolkit, sometimes abbreviated
SSATK) is a collection of higher-level, analysis-ready extensions for the
SSAPy orbital-modeling ecosystem. Where SSAPy
provides the core high-fidelity propagation and modeling engine, the Toolkit
adds astrodynamics utilities, orbital-transfer design, coordinate/time
conversions, brightness and observables modeling, launch and rocket helpers,
integrators, rich plotting, and data I/O to support day-to-day research and
engineering workflows.
SSAPy itself is a fast, flexible, high-fidelity orbital modeling and analysis tool for orbits spanning from low-Earth orbit into the cislunar regime, with configurable force models (Earth and lunar gravity, radiation pressure, drag, planetary perturbations, maneuvers), multiple integrators, orbit determination, Monte Carlo / uncertainty-quantification workflows, and ground/space observer models. See the SSAPy repository for full details: https://github.com/llnl/SSAPy.
- Orbital mechanics & astrodynamics — Keplerian utilities, ellipse fitting, r/v conversions, Lagrange points, and synthetic orbit populations.
- Orbital transfers — a full transfer-design suite: Hohmann, coplanar, Lambert, inclination-change, and rendezvous transfers; continuous-thrust transfers; shooter and optimal-transfer methods; and burn-to-delta-v conversions with finite-burn modeling.
- Coordinate transforms & time conversions — GCRF-to-ITRF, GCRF-to-NTW, GCRF-to-LLH/lon-lat, GCRF-to-lunar, J2000-to-GCRF, Cartesian/spherical/ cylindrical, equatorial/ecliptic, and sky-angle helpers, using a right-handed NTW (N = T x W) convention consistent with SSAPy.
- Observables & brightness modeling — Lambertian magnitude / brightness, including object thermal emission, Earth-shadow effects, and ground reflectance.
- Plotting & visualization — orbit, ground-track, cislunar (2-D and 3-D), and transfer plots; interactive dashboards; and animated GIF/video output.
- Integrators — Runge-Kutta (RK4), leapfrog, and gravity-turn integrators.
- Launch & rockets — launch-pad definitions, gravity-turn ascent, and fuel/burn utilities.
- Data I/O — HDF5 helpers (including dictionary/HDF5 conversion with array handling and selective key loading), plus CSV, JSON, XML, and pickle I/O, and TLE/3LE parsing.
- SSAPy wrappers & HPC helpers — convenience wrappers around SSAPy orbits, propagators, and satellite keyword arguments, plus utilities for HPC workflows.
- Demo gallery — a runnable gallery of worked examples with inline output.
SSAPy Toolkit is a standard Python package.
python -m venv .venv
source .venv/bin/activate # On Windows: .venv\Scripts\activate
pip install --upgrade pip
pip install -e .[dev]
This installs the package in editable mode along with development dependencies (testing, linting, docs tools, etc.). SSAPy Toolkit builds on SSAPy; see the SSAPy repository for its installation details.
The top-level package does not re-export submodules, so import the specific module you need:
from ssapy_toolkit.orbital_mechanics import keplerian
from ssapy_toolkit.orbital_mechanics import transfer_hohmann
from ssapy_toolkit.coordinates import gcrf_to_itrf
from ssapy_toolkit.plots import orbit_plot
More detailed examples can be found in the demos/ directory. To render the
full demo gallery as a visualization document:
ssapy-demo-gallery
To run the test suite:
pytest tests
Code formatting and linting are handled via flake8 (see .flake8 for
configuration).
Project documentation is built with Sphinx and hosted on Read the Docs. Once configured, the latest documentation will be available at:
https://ssapy-toolkit.readthedocs.io
To build the docs locally (after installing dev dependencies):
cd docs
make html
The built HTML files will be in docs/_build/html/.
Contributions are welcome via pull request against the main branch. Work that
primarily concerns the core propagation/modeling engine should target the
SSAPy repository instead.
SSAPy Toolkit is distributed under the terms of the BSD 3-Clause license. All new contributions must be made under the same license. See the LICENSE file for details.
SPDX-License-Identifier: BSD-3-Clause
LLNL-CODE-2015996