Mars has fascinated us for millennia. Almost from the time astronomers first turned their telescopes on the planet shining in the night sky, we've imagined life there. Unlike our other planetary neighbor, Venus, which remains shrouded in cloudy mystery, the red planet has invited speculation and exploration. Since the 1960s, the U.S. and the Soviet Union and, later, Russia and Japan, have launched spacecraft destined to land on or orbit Mars. The successful missions, like the very first Mars flyby in 1964 by the U.S. Mariner 4, have provided a treasure trove of data and, of course, introduced many new questions. Recently, those data, provided compliments of spacecraft such as the Phoenix Mars Lander, the Curiosity rover, and the Mars Reconnaissance Orbiter, have been arriving at Earth at a dizzying rate. It seems like a golden age for Mars exploration has arrived.