The U.S. spacecraft that plunged into the atmosphere of Mars and landed in the Red Planet's northern polar region on Sunday night has begun 90 days of digging in the permafrost to look for evidence of the building blocks of life. Less than two hours after finding its feet, the Phoenix Mars Lander beamed back four dozen black-and-white images including one of its foot sitting on Martian soil amid tiny rocks. Others included the horizon of the arctic plain and ground with polygon patterns similar to what can be found in the earth's permafrost regions.