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English: A close up of Sojourner as it placed its Alpha Proton X-Ray Spectrometer (APXS) upon the surface of the rock "Yogi" was taken by the Imager for Mars Pathfinder (IMP) over sols 8, 9 and 10. Distortion in the background is due to parallax. Early results of Yogi show it to be low in quartz content, and more primitive than the rock Barnacle Bill, and appeared more like the common basalts found on Earth.

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.

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.