Phoenix investigated soil and ice in the martian polar regions. The results of this mission and a comparison with Mars-like sites on Earth provide a basis for considering the limits of life and the possibility of life on Mars in the recent or distant past. Mars-like sites on Earth include arid deserts and the polar regions. Studies of the dry permafrost in Antarctica suggests that the Phoenix site may have been habitable as recently as 5 Myr ago.
Getting Under Europa’s Skin
Tracing Formation and Evolution of Outer Solar System Bodies Through Stable Isotopes and Noble Gas Abundances
Photosynthesis, a Planetary Revolution
Xenon: King of the Gases