Sojourner's excavations brought materials to the surface for examination and allowed estimates of the mechanical properties of the deposits.
This image is of a 7 cm wide excavation through the veneer of a drift. The platy fragment or piece of crust (upper right) was displaced by the rover wheel.
NOTE: original caption as published in Science magazine
Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).
Photojournal note: Sojourner spent 83 days of a planned seven-day mission exploring the Martian terrain, acquiring images, and taking chemical, atmospheric and other measurements. The final data transmission received from Pathfinder was at 10:23 UTC on September 27, 1997. Although mission managers tried to restore full communications during the following five months, the successful mission was terminated on March 10, 1998.