From 1985 to 2000 Joseph Boyce provided scientific leadership to NASA as its Mars exploration program scientist. Boyce draws his clear explanations of Mars's atmosphere, climate, surface, and interior from the monumental findings of the different NASA missions. Beginning with Mariner 4 in 1965 and continuing through the 2001 Mars Odyssey probe, each spacecraft sent to Mars yielded fascinating new discoveries and occasionally overturned earlier findings - especially when trying to answer NASA's ultimate question, "Are we alone?"