These images were acquired by NASA's Phoenix Mars Lander's Surface Stereo Imager on the 21st and 25th days of the mission, or Sols 20 and 24 (June 15 and 18, 2008). They show sublimation of ice in the trench informally called "Dodo-Goldilocks" over the course of four days. In the lower left corner, lumps disappear, similar to the process of evaporation. Image: NASA/JPL-Caltech/University of Arizona/Texas A&M University