Digging by NASA's Phoenix Mars Lander on Aug. 23, 2008, during the 88th
sol (Martian day) since landing, reached a depth about three times greater
than in any trench Phoenix has excavated. The deep trench, informally
called "Stone Soup" is at the borderline between two of the polygon-shaped
hummocks that characterize the arctic plain where Phoenix landed.
The lander's Surface Stereo Imager took this picture of Stone Soup trench
on Sol 88 after the day's digging. The trench is about 25 centimeters (10
inches) wide and about 18 centimeters (7 inches) deep.
When digging trenches near polygon centers, Phoenix has hit a layer of icy
soil, as hard as concrete, about 5 centimeters or 2 inches beneath the
ground surface. In the Stone Soup trench at a polygon margin, the digging
has not yet hit an icy layer like that.
Stone Soup is toward the left, or west, end of the robotic arm's work area
on the north side of the lander.
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.
