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.

With this variation I can demonstrate the "slingshot" effect on a space craft trajectory by flying closely in front of or behind the planet. This uses the same library as the Apollo missions. Changing the tcl scripts is all that is necessary to set up a mars mission.