The Phoenix mission was selected by NASA as the first mission to be flown as part of the Mars Scout program, a highly competitive program that allows diverse groups based within industry, academia or government to propose their own missions, and compete for funding based on comparative merit in science, cost and risk. Under the name "Mars Discovery," this program was first proposed by the Mars Society at its Founding Convention in 1998 as an essential way to enrich the robotic Mars exploration program with a broad array of highly creative concepts drawn from across the scientific community. In 2000 NASA instituted the concept, and subsequently a competition was held, with Phoenix being selected in August 2003 from a field of over thirty competing concepts.

Phoenix will land near the Martian north pole in May 2008 to search for evidence that may help resolve the question of the past or present existence of life on the Red Planet. It will do so by making use of the dormant 2001 Mars lander who planned flight was cancelled after the failure of the Mars Polar lander in 1999. This spacecraft will use a soft landing system employing rocket thrusters, instead of airbags. Such soft landing systems will be essential for future human mission

The Phoenix team is led by Dr.Peter Smith and the Lunar and Planetary Laboratory at the University of Arizona in partnership with the Jet Propulsion Laboratory, Lockheed Martin and the Canadian Space Agency.

Further discussion of the Phoenix mission by Dr. Smith is presented below.

According to Dr. Peter Smith:

Briefly, our mission is to land in the northern polar region of Mars (about 70� N latitude) in May 2008 and to expose the upper few feet of surface material using a robotic arm to find the ice that was discovered by the Odyssey mission in 2002. The history of this ice and its interaction with the Martian atmosphere will be studied throughout the 3-month primary mission. This ice-rich soil may be one of the few habitable environments on Mars where a biological system can survive.

Our mission is visually represented by the fire and water themes in our logo, designed by Isabelle Tremblay in Canada. Our Canadian partners are providing a capable weather station that provides daily pressure and temperature measurements as well as a sophisticated laser system to scan the lower layer of the atmosphere to determine its turbulence and cloudiness. Samples collected from selected depths from the surface to the putative ice layer are treated in several ways. Some are placed into tiny ovens and cooked to drive off vapors; most sedimentary minerals decompose at high temperature. These vapors are tested in a mass spectrometer to find their composition. Organic material will present an easily identified signature. Another test adds water (brought from Earth) to a special beaker prepared with a small sample of soil. The mixture is stirred and the chemistry of the water is determined. Saltiness, acidity, and oxidants can quickly be determined giving us a good description of the environmental conditions to be found when the ice melts. The final test is to examine samples with a high power microscope to understand the shapes of the grains. An atomic force microscope provided by our Swiss colleagues gives the ultimate resolution of the tiniest grains.

All these tests are documented with images. During descent, we take a nested set of ever higher resolution images of our landing site. These serve to locate us within orbital images. After our landing, using an advance propulsion system, the panoramic imager sweeps the horizon for full color, stereoscopic views. High resolution views of landforms, rocks, and even Danish magnets on the spacecraft deck help us understand the local geology. During digging a camera on the robotic arm examines the sampling and the trenching activities to help us in deciding which soils to sample. The microscopes round out the imaging experiments giving us an unprecedented range of scale from 10s of kilometers to 10s of microns; the ultimate in powers of ten from a single mission.

Since the final selection of the Phoenix Scout mission in August of 2003, we have experienced rapid growth and maturation as a project. The six instruments that compose our science payload have all been through their preliminary reviews and are now in the construction and test phase of their development. The flight system, the mothballed 2001 lander, has been thoroughly inspected at Lockheed Martin in preparation for the first major project review in February 2005. Completion and testing of the spacecraft will start in April culminating in a launch in August 2007 from Cape Canaveral in Florida. This year promises to bring rapid progress toward the completion of our flight hardware so that we can begin testing 16 months before launch.

The Phoenix mission rises from the ashes of previous missions and, after a safe landing on Mars, will take another important step toward understanding our neighboring planet. The rover missions have studied the ancient environments where water created rock layers in the ancient past. Phoenix will try to understand the current processes shaping the important northern plains. Are any signatures of Martian life hidden just beneath the surface where icy soil can periodically melt?

Science Goals
The Phoenix lander 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.

Goal 1: Determine whether life ever arose on Mars
Continuing the Viking missions' quest, but in an environment know 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.

Goal 2: Characterize the climate of Mars
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.

Goal 3: Characterize the geology of Mars
As on Earth, the past history of water is written below the surface because liquid water changes the soil chemistry in definite ways. Some scientists speculate the landing site for Phoenix may have be been a deep ocean in the planet's distance 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.

Goal 4: Prepare for human exploration
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.