Sharp new images received Saturday from the Phoenix lander largely convinced scientists that the spacecraft’s thrusters had uncovered a large patch of ice just below the Martian surface, team members said. That bodes well for the mission’s main goal of digging for ice that can be tested for evidence of organic compounds that are the chemical building blocks of life. Team members said Friday that photos showing the ground beneath the lander suggested that the vehicle was resting on splotches of ice. Washington University scientist Ray Arvidson said the spacecraft’s thrusters may have blown away dirt covering the ice when the robot landed one week ago.