Compositions of subsurface ices at the Mars Phoenix landing site

Abstract

NASA's Phoenix Lander uncovered two types of ice at its 2008 landing site on the northern plains of Mars: a brighter, slab‐like ice that broke during Robotic Arm operations; and a darker icy deposit. Spectra from the Phoenix Surface Stereo Imager (SSI) are used to demonstrate that the brighter material consists of nearly pure water ice, which probably formed by migration and freezing of liquid water. The darker icy material consists of ∼30 ± 20 wt% ice, with the remainder composed of fine‐grained soil, indicating that it probably formed as pore ice. These two types of ice represent two different emplacement mechanisms and periods of deposition.