WASHINGTON (AFP) - NASA's three-legged Phoenix Mars Lander is slated to descend onto the planet's north pole region on Sunday on a mission to examine the frigid area's water history, probe the soil for the possibility of life and assess the habitability of the region. Shaped like a cone as it descends, the 420-million-dollar Phoenix will open up after landing to unfurl two solar panels, to resemble a five meter (16 feet) by 1.5 meter (five feet) table. It weighs 350 kilograms (772 lbs), including 25 kilograms (55 pounds) of scientific instruments. The backhoe-like robotic arm, 2.35 meters (7.7 feet) long, is designed to dig trenches and pick up samples of soil and water ice, which it will deliver to instruments for detailed chemical and geological analysis. The robotic arm also carries a box-shaped camera with a double Gauss lens system like that in 35mm cameras, and two lighting assemblies. Located just above the arm's scoop, it will take images of the surrounding area and of samples the arm picks up. Meteorological station: the Canadian-built unit will monitor the daily weather of Mars' northern polar climate, one aim of which is to examine how water cycles between its solid and gas phases in the region. It carries a lidar instrument (for light detection and ranging) which uses laser light pulses to study atmospheric particles in the area.  Surface stereo imager: what NASA calls Phoenix's "eyes," the SSI will produce high-definition and panoramic images of Mars' arctic region. Sitting two meters (6.6 feet) above the ground, its stereo capability will help give scientists on Earth three-dimensional views of the work the robotic arm does. It can also be turned vertically to take images that will provide information on atmospheric particles.