The Program to Optimize Simulated Trajectories II (POST2) is a generalized point mass, discrete parameter targeting and optimization program. POST2 provides the capability to target and optimize point mass trajectories for multiple powered or un-powered vehicles near an arbitrary rotating, oblate planet. POST2 has been used successfully to solve a wide variety of atmospheric ascent and entry problems, as well as exo-atmospheric orbital transfer problems. The generality of the program is evidenced by its multiple phase simulation capability which features generalized planet and vehicle models. This flexible simulation capability is augmented by an efficient discrete parameter optimization capability that includes equality and inequality constraints. POST2 supports NASA’s Strategic Goal to expand the frontiers of knowledge, capability, and opportunity in space by directly contributing to expanding our human and robotic presence into the solar system and to the surface of Mars as well as other planetary bodies.

POST2 is an ITAR restricted code and may only be distributed to approved persons for government use only. Government Use Only – US Government agencies, US military, organizations or companies having contracts or grants with US government and a need for POST2 to support that contract or grant.

Please be advised that under 22 CFR 122, “Any person who engages in the United States in the business of either manufacturing or exporting defense articles or furnishing defense services is required to register with the Office of Defense Trade Controls. Manufacturers who do not engage in exporting must nevertheless register.” For exemptions, procedures, and regulations please see:

Latest Version: POST2 version 4.3D dated June 2020

To request POST2, please visit the Request POST2 page. To check the status of your POST2 request, please contact Software Release Office.