PyKEP is a scientific library providing basic tools to perform research in interplanetary trajectory design or, more generally, in mission analysis. Algorithmic efficiency is a main focus of the library, which is written in C++ and exposed to Python using the boost::python library. At the library core is the implementation of an efficient solver for the multiple revolutions Lambert’s problem, objects representing the Sims-Flanagan low-thrust model, efficient Keplerian propagators, Taylor-integrators and more ...

Check the official documentation at http://esa.github.io/pykep/