Phoenix: The first Mars Scout mission

As the first of the new Mars Scouts missions, the Phoenix project was selected by NASA in August of 2003. Four years later, almost to the day, Phoenix was launched from Cape Canaveral Air Station and successfully injected into an interplanetary trajectory on its way to Mars. On May 25, 2008 Phoenix conducted the first successful powered decent on Mars in over 30 years. This paper will highlight some of the key changes since the 2008 IEEE paper of the same name, as well as performance through cruise, landing at the north pole of Mars and some of the preliminary results of the surface mission.11 Phoenix "Follows the water" responding directly to the recently published data from Dr. William Boynton, PI (and Phoenix co-I) of the Mars Odyssey Gamma Ray Spectrometer (GRS). GRS data indicate extremely large quantities of water ice (up to 50% by mass) within the upper 50 cm of the northern polar regolith. Phoenix will land within the north polar region at 68.3degN, 124.6degW identified by GRS to harbor near surface water ice and provide in-situ confirmation of this extraordinary find. Our mission has investigated water in all its phases, as well as the history of water as evidenced in the soil and atmospheric characteristics. Access to the critical subsurface region which contains this information was made possible by a third generation robotic arm capable of excavating the expected Martian regolith to a depth of 1m. Phoenix had four primary science objectives: (1) Determine the polar climate and weather, interaction with the surface, and composition of the lower atmosphere around 70deg N for at least 90 sols focusing on water, ice, dust, noble gases, and CO₂. Determine the atmospheric characteristics during descent through the atmosphere. (2) Characterize the geomorphology and active processes shaping the northern plains and the physical properties of the near surface regolith focusing on the role of water. (3) Determine the aqueous mineralogy and chemistry as w- ell as the adsorbed gases and organic content of the regolith. Verify the Odyssey discovery of near-surface ice. (4) Characterize the history of water, ice, and the polar climate. Determine the past and present biological potential of the surface and subsurface environments.