Americans got a textbook example of sublimation last week with the release of 'before and after' photos from the Phoenix Mars Lander.
Marble-size clumps of bright material vanished from inside a trench where they were photographed four days earlier, convincing project scientists that the material was frozen water that vaporized after digging exposed it.
The photos at right [credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University] show the clumps in the lower left shadow area of the left photo but gone in the right photo, taken four days later.
Project leader Peter Smith noted that salts will not dissolve or dissipate like this, leaving only ice as the logical conclusion.
That presumes however, that the clumps were not carried off by Martian critters.