A European space probe powered up its dormant systems Friday as it prepared to enter the atmosphere of Saturn's moon Titan on a mission to explore its mysterious surface and hazy atmosphere _ which could hold clues to how life arose on Earth. The European Space Agency's Huygens probe successfully turned itself back on, a key step in the mission, officials at mission control in Darmstadt said. They waited for further signals confirming that the probe had started its descent through the atmosphere. The probe was spun off from the international Cassini mother ship on Christmas Eve and began its free-fall toward the moon's surface, its systems powered down. It was to spring to life just before hitting the upper atmosphere of Titan _ the only moon other than Earth's ever to be explored by spacecraft.
