NASA lander mission; it is the first Mars "Scout class" mission to study the planet's north-pole ice cap, and the geologic history of water and habitability potential in the polar ice-rich soil. Phoenix launched in August, 2007 and touched down on May 25, 2008. The lander's robotic arm will dig down into the subsurface to collect ice and soil samples for onboard analyses by a suite of instruments. Phoenix Mars Mission homepage.