mars trajectory (Score 1)

It depends on what type of mission it is. For most missions (in which time is not an issue), the most energy efficient trajectory is one called the Hohman transfer. It involves an elliptical orbital transfer mechanism (which you can easily find on google). It works by conical patching of elliptical orbits (requiring only two delta v burns/ one to enter and one to exit the transfer). The time between mars-earth on a hohman is i think on the order of 300 days. the calculations are relatively simple and im sure you can find the equations anywhere on the net vince