Mars Pathfinder Description:

Study the Mars mission in exacting detail - accurate to 16 significant digits. Experiment with thrusts, change the configuration of the trajectory to save fuel and time... Plot out the results of each trial graphically, or study the hard numbers. This is the real thing ~ exactly the way NASA does it, right down to the typical five thrust configuration. Everything is there and described in layman's terms, nicely illustrated. The complete source code is also included.