This is a screen shot of my Orbits program. This application combines a C++ library of "body" objects like planets, moons and rockets. SWIG is used to generate tcl wrappers for this library and a tk is used to create the GUI. I found this to be an effective rapid prototyping tool since I could script the missions in tcl and study the effects of changes in the mission profile.

By simply changing the point of view to an earth centered system, this simulator demonstrates a Ptolemy version of the solar system. The epicycles can be seen for the planets. No wonder there were no Roman missions to Mars.