Sojourner is seen here using its Alpha Proton X-Ray Spectrometer (APXS) instrument in a study of the Martian soil. The upper image is of rocky terrain and a portion of Sojourner's antenna, seen at lower right. The image was taken by the Imager for Mars Pathfinder (IMP), standing 1.8 meters above the Martian surface.

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 an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.