PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov PHOTO CAPTION MRPS #81088 July 8, 1997 (Sol 5) Sojourner's APXS at work The image was taken by the Imager for Mars Pathfinder (IMP) on Sol 4. The rover Sojourner has traveled to an area of soil and several rocks. Its tracks are clearly visible in the soft soil seen in the foreground, and were made in part by the rover's material abrasion experiment. Scientists were able to control the force of the rover's cleated wheels to help determine the physical properties of the soil. In this image, Sojourner is using its Alpha Proton X-Ray Spectrometer (APXS) instrument to study an area of soil. Sunlight is striking the area from the left, creating shadows under Sojourner and at the right of local rocks. The large rock Yogi can be seen at upper right. Mars Pathfinder was developed and managed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration. The IMP was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator. #####