Mars is in a slightly elliptical orbit around the Sun and maintains an average distance slightly more than 1.5 AU. The synodic period of Mars is roughly 26 months. This fact makes transfer windows to Mars more common than those to slower-orbiting object, such as Jupiter and Saturn.
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Mars is in a highly elliptical orbit around the Sun and maintains an average distance slightly more than 1.5 AU. The synodic period of Mars is roughly 26 months. This fact makes Mars a particularly difficult object to explore, because opportunities to launch a rocket probe to Mars occur so far apart in time.