Accurate Transfer Orbit Model
C++ CMake Shell
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\cond MIT license Build StatusCoverity Scan Build Status Coverage Status \endcond

Accurate Transfer Orbit Model (Atom) is a C++ template library containing the Atom solver. The Atom solver is an analog of the Lambert solver using the SGP4/SDP4 propagation models.

Details of the solver can be found in Kumar, et al. (2016)

A CMake module is available to make it easy to include Atom in other CMake-based projects: FindAtom.cmake.


  • Header-only
  • Atom solver function with fully-configurable, optional parameters
  • Cartesian-to-TLE conversion function
  • Full suite of tests


To install this project, please ensure that you have installed the following (install guides are provided on the respective websites):

In addition, Atom depends on the following libraries:

  • SML (math library)
  • Astro (astrodynamics library)
  • SGP4 (SGP4/SDP4 library)
  • GSL (GNU scientific library that includes non-linear root-finders used)
  • CATCH (unit testing library necessary for BUILD_TESTS option)
  • Eigen (linear algebra library necessary for BUILD_TESTS_WITH_EIGEN option)

These dependencies will be downloaded and configured automagically if not already present locally (requires an internet connection). It takes a while to install GSL automagically, so it is recommended to pre-install if possible using e.g., Homebrew on Mac OS X, apt-get on Ubuntu, Gsl) on Windows.


Run the following commands to download, build, and install this project.

git clone
cd atom
git submodule init && git submodule update
mkdir build && cd build
cmake .. && cmake --build .

To install the header files, run the following from within the build directory:

make install

Note that dependencies are installed by fetching them online, in case they cannot be detected on your local system. If the build process fails, check the error log given. Typically, building fails due to timeout. Simply run the cmake --build . command once more.

Build options

You can pass the following, general command-line options when running CMake:

  • -DCMAKE_INSTALL_PREFIX[=$install_dir]: set path prefix for install script (make install); if not set, defaults to usual locations
  • -DBUILD_DOXYGEN_DOCS[=ON|OFF (default)]: build the Doxygen documentation (LaTeX must be installed with amsmath package)
  • -DBUILD_TESTS[=ON|OFF (default)]: build tests (execute tests from build-directory using ctest -V)
  • -DBUILD_DEPENDENCIES[=ON|OFF (default)]: force local build of dependencies, instead of first searching system-wide using find_package()

The following commands are conditional and can only be set if BUILD_TESTS = ON:

  • -DBUILD_TESTS_WITH_EIGEN[=ON|OFF (default)]: build tests using Eigen (execute tests from build-directory using ctest -V)
  • -DBUILD_COVERAGE_ANALYSIS[=ON|OFF (default)]: build code coverage using Gcov and LCOV (both must be installed; requires GCC compiler; execute coverage analysis from build-directory using make coverage)

Pass these options either directly to the cmake .. build command or run ccmake .. instead to bring up the interface that can be used to toggle options.

Project structure

This project has been set up with a specific file/folder structure in mind. The following describes some important features of this setup:

  • cmake/Modules : Contains CMake modules, including FindAtom.cmake template for project-specific module
  • docs: Contains project-specific docs in Markdown that are also parsed by Doxygen. This sub-directory includes, which contains a global list of TODO items for project that appear on TODO list generated in Doxygen documentation
  • doxydocs: HTML output generated by building Doxygen documentation
  • include/Atom: Project header files (*.hpp)
  • scripts: Shell scripts used in Travis CI build
  • test: Project test source files (*.cpp), including testAtom.cpp, which contains include for Catch
  • .travis.yml: Configuration file for Travis CI build, including static analysis using Coverity Scan and code coverage using Coveralls
  • CMakeLists.txt: main CMakelists.txt file for project (should not need to be modified for basic build)
  • Dependencies.cmake: list of dependencies and automated build, triggered if dependency cannot be found locally
  • Doxygen configuration file, adapted for generic use within project build (should not need to be modified)
  • license file for project
  • ProjectFiles.cmake: list of project source files to build
  • project readme file, parsed as main page for Doxygen documentation


Once you've made your great commits:

  1. Fork Atom
  2. Create a topic branch - git checkout -b my_branch
  3. Push to your branch - git push origin my_branch
  4. Create a Pull Request from your branch
  5. That's it!


The copyright holders are not liable for any damage(s) incurred due to improper use of Atom.