NASA Science Goals
Phoenix seeks to verify the presence of the Martian Holy Grail: water and habitable conditions. In doing so, the mission strongly complements the four goals of NASA's Mars Exploration Program.
Continuing the Viking missions' quest, but in an environment known to be water-rich, Phoenix searches for signatures of life at the soil-ice interface just below the Martian surface. Phoenix will land in the artic plains, where its robotic arm will dig through the dry soil to reach the ice layer, bring the soil and ice samples to the lander platform, and analyze these samples using advanced scientific instruments. These samples may hold the key to understanding whether the Martian arctic is a habitable zone where microbes could grow and reproduce during moist conditions.
Phoenix will land during the retreat of the Martian polar cap, when cold soil is first exposed to sunlight after a long winter. The interaction between the ground surface and the Martian atmosphere that occurs at this time is critical to understanding the present and past climate of Mars. To gather data about this interaction and other surface meteorological conditions, Phoenix will provide the first weather station in the Martian polar region, with no others currently planned. Data from this station will have a significant impact in improving global climate models of Mars.
As on Earth, the past history of water is written below the surface because liquid water changes the soil chemistry and mineralogy in definite ways. Phoenix will use a suite of chemistry experiments to thoroughly analyze the soil's chemistry and mineralogy. Some scientists speculate the landing site for Phoenix may have been a deep ocean in the planet's distant past leaving evidence of sedimentation. If fine sediments of mud and silt are found at the site, it may support the hypothesis of an ancient ocean. Alternatively, coarse sediments of sand might indicate past flowing water, especially if these grains are rounded and well sorted. Using the first true microscope on Mars, Phoenix will examine the structure of these grains to better answer these questions about water's influence on the geology of Mars.
The Phoenix Mission will provide evidence of water ice and assess the soil chemistry in Martian arctic. Water will be a critical resource to future human explorers and Phoenix may provide appreciable information on how water may be acquired on the planet. Understanding the soil chemistry will provide understanding of the potential resources available for human explorers to the northern plains.