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These four images highlight the types of scientific experiments and engineering tests that the rover Sojourner has conducted on Mars. Three of the images were taken by the Imager for Mars Pathfinder (IMP) camera. A fourth image was taken by one of the three cameras on board the rover.
Sojourner at "Barnacle Bill"
Sojourner's first analysis of a rock on Mars began on Sol 3 (Mars Pathfinder's third Martian day) with the study of Barnacle Bill, a nearby rock named for its rough surface. The Alpha Proton X-ray Spectrometer (APXS) is used to determine the elements that make up the rocks and soil on Mars. A full study using the APXS takes approximately 10 hours. It measures all elements, except hydrogen, as long as they make up at least 1/lOth of I percent of the mass of the rock or soil. The APXS conducts its studies by bombarding rocks and soil samples with alpha particle radiation_ charged particles equivalent to the nucleus of a helium atom, consisting of two protons and two neutrons. Results indicated that Barnacle Bill is similar in composition to Earth rock known as andesite. On Earth, andesite is produced through repeated cycles of melting and solid)fication, such as volcanic activity.
Soil Measurements
This image was taken by the IMP camera on Sol 4. Sojourner has traveled to an area of soil and several rocks. Rover 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 has lowered its APXS instrument to the surface to study an area of soil. A small portion of the rock Yogi and its shadow can be seen in the upper right corner. The three rocks just above and to the left of Sojourner's solar panel are called The Dice.
Rover's-Eye View of Lander
On Sol 26 one of the two forward facing cameras aboard the Sojourner rover took this image of the lander, which has been named the Carl Sagan Memorial Station after the late astronomer. Features seen on the lander include (from left to .right) the Atmospheric Structure Instrument/Meteorology Package (ASI/MET) mast with windsocks, the low-gain antenna mast, the disc-shaped high-gain antenna angled off to the right and pointed at Earth, and areas of deflated airbags. The dark circle on the lander body is a filtered vent that allowed air to escape during launch, and allowed the lander to repressurize upon landing. Mini Matterhorn is the large rock in front of the lander to the left.
Sojourner Does a Wheelie at Yogi
Sojourner has made contact with the rock Yogi in this image, taken on Sol 6. The rover's left rear wheel has driven up onto Yogi's surface in an attempt to get as close as possible to the rock's surface. Sojourner later drove off Yogi and returned at a slightly different angle, placing its APXS instrument against the rock to conduct a study of its chemical composition. This observation indicated that Yogi has had a different geological history than Barnacle Bill; it is a more primitive basaltic igneous rock.
This image and additional information about the Mars Pathfinder mission can be found on the Internet at: http://mpfwww.jpl.nasa.gov
The Mars Pathfinder mission is part of a long-term program of Mars exploration being conducted by NASA's Office of Space Science. The Jet Propulsion Laboratory, an operating division of the Calitornia Institute of Technology, manages the Mars Exploration Program tor NASA.
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