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 19, 2008).
These images 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.
The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.
Image credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University